merge default into stable for 5.2 release

black.toml

@@ -0,0 +1,17 b''
+[tool.black]
+line-length = 80
+exclude = '''
+build/
+| wheelhouse/
+| dist/
+| packages/
+| \.hg/
+| \.mypy_cache/
+| \.venv/
+| mercurial/thirdparty/
+| hgext/fsmonitor/pywatchman/
+| contrib/python-zstandard/
+| contrib/grey.py
+'''
+skip-string-normalization = true
+quiet = true

contrib/automation/hgautomation/pypi.py

@@ -0,0 +1,21 b''
+# pypi.py - Automation around PyPI
+#
+# Copyright 2019 Gregory Szorc <[e-mail]>
+#
+# This software may be used and distributed according to the terms of the
+# GNU General Public License version 2 or any later version.
+
+# no-check-code because Python 3 native.
+
+from twine.commands.upload import upload as twine_upload
+from twine.settings import Settings
+
+
+def upload(paths):
+    """Upload files to PyPI.
+
+    `paths` is an iterable of `pathlib.Path`.
+    """
+    settings = Settings()
+
+    twine_upload(settings, [str(p) for p in paths])

contrib/automation/hgautomation/try_server.py

@@ -0,0 +1,99 b''
+# try_server.py - Interact with Try server
+#
+# Copyright 2019 Gregory Szorc <[e-mail]>
+#
+# This software may be used and distributed according to the terms of the
+# GNU General Public License version 2 or any later version.
+
+# no-check-code because Python 3 native.
+
+import base64
+import json
+import os
+import subprocess
+import tempfile
+
+from .aws import AWSConnection
+
+LAMBDA_FUNCTION = "ci-try-server-upload"
+
+
+def trigger_try(c: AWSConnection, rev="."):
+    """Trigger a new Try run."""
+    lambda_client = c.session.client("lambda")
+
+    cset, bundle = generate_bundle(rev=rev)
+
+    payload = {
+        "bundle": base64.b64encode(bundle).decode("utf-8"),
+        "node": cset["node"],
+        "branch": cset["branch"],
+        "user": cset["user"],
+        "message": cset["desc"],
+    }
+
+    print("resolved revision:")
+    print("node: %s" % cset["node"])
+    print("branch: %s" % cset["branch"])
+    print("user: %s" % cset["user"])
+    print("desc: %s" % cset["desc"].splitlines()[0])
+    print()
+
+    print("sending to Try...")
+    res = lambda_client.invoke(
+        FunctionName=LAMBDA_FUNCTION,
+        InvocationType="RequestResponse",
+        Payload=json.dumps(payload).encode("utf-8"),
+    )
+
+    body = json.load(res["Payload"])
+    for message in body:
+        print("remote: %s" % message)
+
+
+def generate_bundle(rev="."):
+    """Generate a bundle suitable for use by the Try service.
+
+    Returns a tuple of revision metadata and raw Mercurial bundle data.
+    """
+    # `hg bundle` doesn't support streaming to stdout. So we use a temporary
+    # file.
+    path = None
+    try:
+        fd, path = tempfile.mkstemp(prefix="hg-bundle-", suffix=".hg")
+        os.close(fd)
+
+        args = [
+            "hg",
+            "bundle",
+            "--type",
+            "gzip-v2",
+            "--base",
+            "public()",
+            "--rev",
+            rev,
+            path,
+        ]
+
+        print("generating bundle...")
+        subprocess.run(args, check=True)
+
+        with open(path, "rb") as fh:
+            bundle_data = fh.read()
+
+    finally:
+        if path:
+            os.unlink(path)
+
+    args = [
+        "hg",
+        "log",
+        "-r",
+        rev,
+        # We have to upload as JSON, so it won't matter if we emit binary
+        # since we need to normalize to UTF-8.
+        "-T",
+        "json",
+    ]
+    res = subprocess.run(args, check=True, capture_output=True)
+    return json.loads(res.stdout)[0], bundle_data

contrib/examples/fix.hgrc

@@ -0,0 +1,15 b''
+[fix]
+clang-format:command = clang-format --style file -i
+clang-format:pattern = (**.c or **.cc or **.h) and not "listfile:contrib/clang-format-ignorelist"
+
+rustfmt:command = rustfmt {rootpath}
+rustfmt:pattern = set:**.rs
+
+# We use black, but currently with
+# https://github.com/psf/black/pull/826 applied. For now
+# contrib/grey.py is our fork of black. You need to pip install
+# git+https://github.com/python/black/@d9e71a75ccfefa3d9156a64c03313a0d4ad981e5
+# to have the dependencies for grey.
+#
+# black:command = python3.7 contrib/grey.py --config=black.toml -
+# black:pattern = set:**.py - hgext/fsmonitor/pywatchman/** - mercurial/thirdparty/** - "contrib/python-zstandard/** - contrib/grey.py"

contrib/fuzz/dirs.cc

@@ -0,0 +1,56 b''
+#include <Python.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "pyutil.h"
+
+#include <string>
+
+extern "C" {
+
+static PyCodeObject *code;
+
+extern "C" int LLVMFuzzerInitialize(int *argc, char ***argv)
+{
+	contrib::initpy(*argv[0]);
+	code = (PyCodeObject *)Py_CompileString(R"py(
+from parsers import dirs
+try:
+  files = mdata.split('\n')
+  d = dirs(files)
+  list(d)
+  'a' in d
+  if files:
+    files[0] in d
+except Exception as e:
+  pass
+  # uncomment this print if you're editing this Python code
+  # to debug failures.
+  # print e
+)py",
+	                                        "fuzzer", Py_file_input);
+	return 0;
+}
+
+int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size)
+{
+	// Don't allow fuzzer inputs larger than 100k, since we'll just bog
+	// down and not accomplish much.
+	if (Size > 100000) {
+		return 0;
+	}
+	PyObject *mtext =
+	    PyBytes_FromStringAndSize((const char *)Data, (Py_ssize_t)Size);
+	PyObject *locals = PyDict_New();
+	PyDict_SetItemString(locals, "mdata", mtext);
+	PyObject *res = PyEval_EvalCode(code, contrib::pyglobals(), locals);
+	if (!res) {
+		PyErr_Print();
+	}
+	Py_XDECREF(res);
+	Py_DECREF(locals);
+	Py_DECREF(mtext);
+	return 0; // Non-zero return values are reserved for future use.
+}
+}

contrib/fuzz/fncache.cc

@@ -0,0 +1,78 b''
+#include <Python.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "pyutil.h"
+
+#include <iostream>
+#include <string>
+
+extern "C" {
+
+static PyCodeObject *code;
+
+extern "C" int LLVMFuzzerInitialize(int *argc, char ***argv)
+{
+	contrib::initpy(*argv[0]);
+	code = (PyCodeObject *)Py_CompileString(R"py(
+from parsers import (
+    isasciistr,
+    asciilower,
+    asciiupper,
+    encodedir,
+    pathencode,
+    lowerencode,
+)
+
+try:
+    for fn in (
+        isasciistr,
+        asciilower,
+        asciiupper,
+        encodedir,
+        pathencode,
+        lowerencode,
+    ):
+        try:
+            fn(data)
+        except UnicodeDecodeError:
+            pass  # some functions emit this exception
+        except AttributeError:
+            # pathencode needs hashlib, which fails to import because the time
+            # module fails to import. We should try and fix that some day, but
+            # for now we at least get coverage on non-hashencoded codepaths.
+            if fn != pathencode:
+                raise
+        # uncomment this for debugging exceptions
+        # except Exception as e:
+        #     raise Exception('%r: %r' % (fn, e))
+except Exception as e:
+    pass
+    # uncomment this print if you're editing this Python code
+    # to debug failures.
+    # print(e)
+)py",
+	                                        "fuzzer", Py_file_input);
+	if (!code) {
+		std::cerr << "failed to compile Python code!" << std::endl;
+	}
+	return 0;
+}
+
+int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size)
+{
+	PyObject *mtext =
+	    PyBytes_FromStringAndSize((const char *)Data, (Py_ssize_t)Size);
+	PyObject *locals = PyDict_New();
+	PyDict_SetItemString(locals, "data", mtext);
+	PyObject *res = PyEval_EvalCode(code, contrib::pyglobals(), locals);
+	if (!res) {
+		PyErr_Print();
+	}
+	Py_XDECREF(res);
+	Py_DECREF(locals);
+	Py_DECREF(mtext);
+	return 0; // Non-zero return values are reserved for future use.
+}
+}

contrib/fuzz/jsonescapeu8fast.cc

@@ -0,0 +1,57 b''
+#include <Python.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "pyutil.h"
+
+#include <fuzzer/FuzzedDataProvider.h>
+#include <iostream>
+#include <string>
+
+extern "C" {
+
+static PyCodeObject *code;
+
+extern "C" int LLVMFuzzerInitialize(int *argc, char ***argv)
+{
+	contrib::initpy(*argv[0]);
+	code = (PyCodeObject *)Py_CompileString(R"py(
+from parsers import jsonescapeu8fast
+
+try:
+    jsonescapeu8fast(data, paranoid)
+except Exception as e:
+    pass
+    # uncomment this print if you're editing this Python code
+    # to debug failures.
+    # print(e)
+)py",
+	                                        "fuzzer", Py_file_input);
+	if (!code) {
+		std::cerr << "failed to compile Python code!" << std::endl;
+	}
+	return 0;
+}
+
+int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size)
+{
+	FuzzedDataProvider provider(Data, Size);
+	bool paranoid = provider.ConsumeBool();
+	std::string remainder = provider.ConsumeRemainingBytesAsString();
+
+	PyObject *mtext = PyBytes_FromStringAndSize(
+	    (const char *)remainder.c_str(), remainder.size());
+	PyObject *locals = PyDict_New();
+	PyDict_SetItemString(locals, "data", mtext);
+	PyDict_SetItemString(locals, "paranoid", paranoid ? Py_True : Py_False);
+	PyObject *res = PyEval_EvalCode(code, contrib::pyglobals(), locals);
+	if (!res) {
+		PyErr_Print();
+	}
+	Py_XDECREF(res);
+	Py_DECREF(locals);
+	Py_DECREF(mtext);
+	return 0; // Non-zero return values are reserved for future use.
+}
+}

contrib/grey.py

@@ -0,0 +1,4094 b''
+# no-check-code because 3rd party
+import ast
+import asyncio
+from concurrent.futures import Executor, ProcessPoolExecutor
+from contextlib import contextmanager
+from datetime import datetime
+from enum import Enum
+from functools import lru_cache, partial, wraps
+import io
+import itertools
+import logging
+from multiprocessing import Manager, freeze_support
+import os
+from pathlib import Path
+import pickle
+import re
+import signal
+import sys
+import tempfile
+import tokenize
+import traceback
+from typing import (
+    Any,
+    Callable,
+    Collection,
+    Dict,
+    Generator,
+    Generic,
+    Iterable,
+    Iterator,
+    List,
+    Optional,
+    Pattern,
+    Sequence,
+    Set,
+    Tuple,
+    TypeVar,
+    Union,
+    cast,
+)
+
+from appdirs import user_cache_dir
+from attr import dataclass, evolve, Factory
+import click
+import toml
+from typed_ast import ast3, ast27
+
+# lib2to3 fork
+from blib2to3.pytree import Node, Leaf, type_repr
+from blib2to3 import pygram, pytree
+from blib2to3.pgen2 import driver, token
+from blib2to3.pgen2.grammar import Grammar
+from blib2to3.pgen2.parse import ParseError
+
+__version__ = '19.3b1.dev95+gdc1add6.d20191005'
+
+DEFAULT_LINE_LENGTH = 88
+DEFAULT_EXCLUDES = (
+    r"/(\.eggs|\.git|\.hg|\.mypy_cache|\.nox|\.tox|\.venv|_build|buck-out|build|dist)/"
+)
+DEFAULT_INCLUDES = r"\.pyi?$"
+CACHE_DIR = Path(user_cache_dir("black", version=__version__))
+
+
+# types
+FileContent = str
+Encoding = str
+NewLine = str
+Depth = int
+NodeType = int
+LeafID = int
+Priority = int
+Index = int
+LN = Union[Leaf, Node]
+SplitFunc = Callable[["Line", Collection["Feature"]], Iterator["Line"]]
+Timestamp = float
+FileSize = int
+CacheInfo = Tuple[Timestamp, FileSize]
+Cache = Dict[Path, CacheInfo]
+out = partial(click.secho, bold=True, err=True)
+err = partial(click.secho, fg="red", err=True)
+
+pygram.initialize(CACHE_DIR)
+syms = pygram.python_symbols
+
+
+class NothingChanged(UserWarning):
+    """Raised when reformatted code is the same as source."""
+
+
+class CannotSplit(Exception):
+    """A readable split that fits the allotted line length is impossible."""
+
+
+class InvalidInput(ValueError):
+    """Raised when input source code fails all parse attempts."""
+
+
+class WriteBack(Enum):
+    NO = 0
+    YES = 1
+    DIFF = 2
+    CHECK = 3
+
+    @classmethod
+    def from_configuration(cls, *, check: bool, diff: bool) -> "WriteBack":
+        if check and not diff:
+            return cls.CHECK
+
+        return cls.DIFF if diff else cls.YES
+
+
+class Changed(Enum):
+    NO = 0
+    CACHED = 1
+    YES = 2
+
+
+class TargetVersion(Enum):
+    PY27 = 2
+    PY33 = 3
+    PY34 = 4
+    PY35 = 5
+    PY36 = 6
+    PY37 = 7
+    PY38 = 8
+
+    def is_python2(self) -> bool:
+        return self is TargetVersion.PY27
+
+
+PY36_VERSIONS = {TargetVersion.PY36, TargetVersion.PY37, TargetVersion.PY38}
+
+
+class Feature(Enum):
+    # All string literals are unicode
+    UNICODE_LITERALS = 1
+    F_STRINGS = 2
+    NUMERIC_UNDERSCORES = 3
+    TRAILING_COMMA_IN_CALL = 4
+    TRAILING_COMMA_IN_DEF = 5
+    # The following two feature-flags are mutually exclusive, and exactly one should be
+    # set for every version of python.
+    ASYNC_IDENTIFIERS = 6
+    ASYNC_KEYWORDS = 7
+    ASSIGNMENT_EXPRESSIONS = 8
+    POS_ONLY_ARGUMENTS = 9
+
+
+VERSION_TO_FEATURES: Dict[TargetVersion, Set[Feature]] = {
+    TargetVersion.PY27: {Feature.ASYNC_IDENTIFIERS},
+    TargetVersion.PY33: {Feature.UNICODE_LITERALS, Feature.ASYNC_IDENTIFIERS},
+    TargetVersion.PY34: {Feature.UNICODE_LITERALS, Feature.ASYNC_IDENTIFIERS},
+    TargetVersion.PY35: {
+        Feature.UNICODE_LITERALS,
+        Feature.TRAILING_COMMA_IN_CALL,
+        Feature.ASYNC_IDENTIFIERS,
+    },
+    TargetVersion.PY36: {
+        Feature.UNICODE_LITERALS,
+        Feature.F_STRINGS,
+        Feature.NUMERIC_UNDERSCORES,
+        Feature.TRAILING_COMMA_IN_CALL,
+        Feature.TRAILING_COMMA_IN_DEF,
+        Feature.ASYNC_IDENTIFIERS,
+    },
+    TargetVersion.PY37: {
+        Feature.UNICODE_LITERALS,
+        Feature.F_STRINGS,
+        Feature.NUMERIC_UNDERSCORES,
+        Feature.TRAILING_COMMA_IN_CALL,
+        Feature.TRAILING_COMMA_IN_DEF,
+        Feature.ASYNC_KEYWORDS,
+    },
+    TargetVersion.PY38: {
+        Feature.UNICODE_LITERALS,
+        Feature.F_STRINGS,
+        Feature.NUMERIC_UNDERSCORES,
+        Feature.TRAILING_COMMA_IN_CALL,
+        Feature.TRAILING_COMMA_IN_DEF,
+        Feature.ASYNC_KEYWORDS,
+        Feature.ASSIGNMENT_EXPRESSIONS,
+        Feature.POS_ONLY_ARGUMENTS,
+    },
+}
+
+
+@dataclass
+class FileMode:
+    target_versions: Set[TargetVersion] = Factory(set)
+    line_length: int = DEFAULT_LINE_LENGTH
+    string_normalization: bool = True
+    is_pyi: bool = False
+
+    def get_cache_key(self) -> str:
+        if self.target_versions:
+            version_str = ",".join(
+                str(version.value)
+                for version in sorted(self.target_versions, key=lambda v: v.value)
+            )
+        else:
+            version_str = "-"
+        parts = [
+            version_str,
+            str(self.line_length),
+            str(int(self.string_normalization)),
+            str(int(self.is_pyi)),
+        ]
+        return ".".join(parts)
+
+
+def supports_feature(target_versions: Set[TargetVersion], feature: Feature) -> bool:
+    return all(feature in VERSION_TO_FEATURES[version] for version in target_versions)
+
+
+def read_pyproject_toml(
+    ctx: click.Context, param: click.Parameter, value: Union[str, int, bool, None]
+) -> Optional[str]:
+    """Inject Black configuration from "pyproject.toml" into defaults in `ctx`.
+
+    Returns the path to a successfully found and read configuration file, None
+    otherwise.
+    """
+    assert not isinstance(value, (int, bool)), "Invalid parameter type passed"
+    if not value:
+        root = find_project_root(ctx.params.get("src", ()))
+        path = root / "pyproject.toml"
+        if path.is_file():
+            value = str(path)
+        else:
+            return None
+
+    try:
+        pyproject_toml = toml.load(value)
+        config = pyproject_toml.get("tool", {}).get("black", {})
+    except (toml.TomlDecodeError, OSError) as e:
+        raise click.FileError(
+            filename=value, hint=f"Error reading configuration file: {e}"
+        )
+
+    if not config:
+        return None
+
+    if ctx.default_map is None:
+        ctx.default_map = {}
+    ctx.default_map.update(  # type: ignore  # bad types in .pyi
+        {k.replace("--", "").replace("-", "_"): v for k, v in config.items()}
+    )
+    return value
+
+
[e-mail](context_settings=dict(help_option_names=["-h", "--help"]))
[e-mail]("-c", "--code", type=str, help="Format the code passed in as a string.")
[e-mail](
+    "-l",
+    "--line-length",
+    type=int,
+    default=DEFAULT_LINE_LENGTH,
+    help="How many characters per line to allow.",
+    show_default=True,
+)
[e-mail](
+    "-t",
+    "--target-version",
+    type=click.Choice([v.name.lower() for v in TargetVersion]),
+    callback=lambda c, p, v: [TargetVersion[val.upper()] for val in v],
+    multiple=True,
+    help=(
+        "Python versions that should be supported by Black's output. [default: "
+        "per-file auto-detection]"
+    ),
+)
[e-mail](
+    "--py36",
+    is_flag=True,
+    help=(
+        "Allow using Python 3.6-only syntax on all input files.  This will put "
+        "trailing commas in function signatures and calls also after *args and "
+        "**kwargs. Deprecated; use --target-version instead. "
+        "[default: per-file auto-detection]"
+    ),
+)
[e-mail](
+    "--pyi",
+    is_flag=True,
+    help=(
+        "Format all input files like typing stubs regardless of file extension "
+        "(useful when piping source on standard input)."
+    ),
+)
[e-mail](
+    "-S",
+    "--skip-string-normalization",
+    is_flag=True,
+    help="Don't normalize string quotes or prefixes.",
+)
[e-mail](
+    "--check",
+    is_flag=True,
+    help=(
+        "Don't write the files back, just return the status.  Return code 0 "
+        "means nothing would change.  Return code 1 means some files would be "
+        "reformatted.  Return code 123 means there was an internal error."
+    ),
+)
[e-mail](
+    "--diff",
+    is_flag=True,
+    help="Don't write the files back, just output a diff for each file on stdout.",
+)
[e-mail](
+    "--fast/--safe",
+    is_flag=True,
+    help="If --fast given, skip temporary sanity checks. [default: --safe]",
+)
[e-mail](
+    "--include",
+    type=str,
+    default=DEFAULT_INCLUDES,
+    help=(
+        "A regular expression that matches files and directories that should be "
+        "included on recursive searches.  An empty value means all files are "
+        "included regardless of the name.  Use forward slashes for directories on "
+        "all platforms (Windows, too).  Exclusions are calculated first, inclusions "
+        "later."
+    ),
+    show_default=True,
+)
[e-mail](
+    "--exclude",
+    type=str,
+    default=DEFAULT_EXCLUDES,
+    help=(
+        "A regular expression that matches files and directories that should be "
+        "excluded on recursive searches.  An empty value means no paths are excluded. "
+        "Use forward slashes for directories on all platforms (Windows, too).  "
+        "Exclusions are calculated first, inclusions later."
+    ),
+    show_default=True,
+)
[e-mail](
+    "-q",
+    "--quiet",
+    is_flag=True,
+    help=(
+        "Don't emit non-error messages to stderr. Errors are still emitted; "
+        "silence those with 2>/dev/null."
+    ),
+)
[e-mail](
+    "-v",
+    "--verbose",
+    is_flag=True,
+    help=(
+        "Also emit messages to stderr about files that were not changed or were "
+        "ignored due to --exclude=."
+    ),
+)
[e-mail]_option(version=__version__)
[e-mail](
+    "src",
+    nargs=-1,
+    type=click.Path(
+        exists=True, file_okay=True, dir_okay=True, readable=True, allow_dash=True
+    ),
+    is_eager=True,
+)
[e-mail](
+    "--config",
+    type=click.Path(
+        exists=False, file_okay=True, dir_okay=False, readable=True, allow_dash=False
+    ),
+    is_eager=True,
+    callback=read_pyproject_toml,
+    help="Read configuration from PATH.",
+)
[e-mail]_context
+def main(
+    ctx: click.Context,
+    code: Optional[str],
+    line_length: int,
+    target_version: List[TargetVersion],
+    check: bool,
+    diff: bool,
+    fast: bool,
+    pyi: bool,
+    py36: bool,
+    skip_string_normalization: bool,
+    quiet: bool,
+    verbose: bool,
+    include: str,
+    exclude: str,
+    src: Tuple[str],
+    config: Optional[str],
+) -> None:
+    """The uncompromising code formatter."""
+    write_back = WriteBack.from_configuration(check=check, diff=diff)
+    if target_version:
+        if py36:
+            err(f"Cannot use both --target-version and --py36")
+            ctx.exit(2)
+        else:
+            versions = set(target_version)
+    elif py36:
+        err(
+            "--py36 is deprecated and will be removed in a future version. "
+            "Use --target-version py36 instead."
+        )
+        versions = PY36_VERSIONS
+    else:
+        # We'll autodetect later.
+        versions = set()
+    mode = FileMode(
+        target_versions=versions,
+        line_length=line_length,
+        is_pyi=pyi,
+        string_normalization=not skip_string_normalization,
+    )
+    if config and verbose:
+        out(f"Using configuration from {config}.", bold=False, fg="blue")
+    if code is not None:
+        print(format_str(code, mode=mode))
+        ctx.exit(0)
+    try:
+        include_regex = re_compile_maybe_verbose(include)
+    except re.error:
+        err(f"Invalid regular expression for include given: {include!r}")
+        ctx.exit(2)
+    try:
+        exclude_regex = re_compile_maybe_verbose(exclude)
+    except re.error:
+        err(f"Invalid regular expression for exclude given: {exclude!r}")
+        ctx.exit(2)
+    report = Report(check=check, quiet=quiet, verbose=verbose)
+    root = find_project_root(src)
+    sources: Set[Path] = set()
+    path_empty(src, quiet, verbose, ctx)
+    for s in src:
+        p = Path(s)
+        if p.is_dir():
+            sources.update(
+                gen_python_files_in_dir(p, root, include_regex, exclude_regex, report)
+            )
+        elif p.is_file() or s == "-":
+            # if a file was explicitly given, we don't care about its extension
+            sources.add(p)
+        else:
+            err(f"invalid path: {s}")
+    if len(sources) == 0:
+        if verbose or not quiet:
+            out("No Python files are present to be formatted. Nothing to do 😴")
+        ctx.exit(0)
+
+    if len(sources) == 1:
+        reformat_one(
+            src=sources.pop(),
+            fast=fast,
+            write_back=write_back,
+            mode=mode,
+            report=report,
+        )
+    else:
+        reformat_many(
+            sources=sources, fast=fast, write_back=write_back, mode=mode, report=report
+        )
+
+    if verbose or not quiet:
+        out("Oh no! 💥 💔 💥" if report.return_code else "All done! ✨ 🍰 ✨")
+        click.secho(str(report), err=True)
+    ctx.exit(report.return_code)
+
+
+def path_empty(src: Tuple[str], quiet: bool, verbose: bool, ctx: click.Context) -> None:
+    """
+    Exit if there is no `src` provided for formatting
+    """
+    if not src:
+        if verbose or not quiet:
+            out("No Path provided. Nothing to do 😴")
+            ctx.exit(0)
+
+
+def reformat_one(
+    src: Path, fast: bool, write_back: WriteBack, mode: FileMode, report: "Report"
+) -> None:
+    """Reformat a single file under `src` without spawning child processes.
+
+    `fast`, `write_back`, and `mode` options are passed to
+    :func:`format_file_in_place` or :func:`format_stdin_to_stdout`.
+    """
+    try:
+        changed = Changed.NO
+        if not src.is_file() and str(src) == "-":
+            if format_stdin_to_stdout(fast=fast, write_back=write_back, mode=mode):
+                changed = Changed.YES
+        else:
+            cache: Cache = {}
+            if write_back != WriteBack.DIFF:
+                cache = read_cache(mode)
+                res_src = src.resolve()
+                if res_src in cache and cache[res_src] == get_cache_info(res_src):
+                    changed = Changed.CACHED
+            if changed is not Changed.CACHED and format_file_in_place(
+                src, fast=fast, write_back=write_back, mode=mode
+            ):
+                changed = Changed.YES
+            if (write_back is WriteBack.YES and changed is not Changed.CACHED) or (
+                write_back is WriteBack.CHECK and changed is Changed.NO
+            ):
+                write_cache(cache, [src], mode)
+        report.done(src, changed)
+    except Exception as exc:
+        report.failed(src, str(exc))
+
+
+def reformat_many(
+    sources: Set[Path],
+    fast: bool,
+    write_back: WriteBack,
+    mode: FileMode,
+    report: "Report",
+) -> None:
+    """Reformat multiple files using a ProcessPoolExecutor."""
+    loop = asyncio.get_event_loop()
+    worker_count = os.cpu_count()
+    if sys.platform == "win32":
+        # Work around https://bugs.python.org/issue26903
+        worker_count = min(worker_count, 61)
+    executor = ProcessPoolExecutor(max_workers=worker_count)
+    try:
+        loop.run_until_complete(
+            schedule_formatting(
+                sources=sources,
+                fast=fast,
+                write_back=write_back,
+                mode=mode,
+                report=report,
+                loop=loop,
+                executor=executor,
+            )
+        )
+    finally:
+        shutdown(loop)
+        executor.shutdown()
+
+
+async def schedule_formatting(
+    sources: Set[Path],
+    fast: bool,
+    write_back: WriteBack,
+    mode: FileMode,
+    report: "Report",
+    loop: asyncio.AbstractEventLoop,
+    executor: Executor,
+) -> None:
+    """Run formatting of `sources` in parallel using the provided `executor`.
+
+    (Use ProcessPoolExecutors for actual parallelism.)
+
+    `write_back`, `fast`, and `mode` options are passed to
+    :func:`format_file_in_place`.
+    """
+    cache: Cache = {}
+    if write_back != WriteBack.DIFF:
+        cache = read_cache(mode)
+        sources, cached = filter_cached(cache, sources)
+        for src in sorted(cached):
+            report.done(src, Changed.CACHED)
+    if not sources:
+        return
+
+    cancelled = []
+    sources_to_cache = []
+    lock = None
+    if write_back == WriteBack.DIFF:
+        # For diff output, we need locks to ensure we don't interleave output
+        # from different processes.
+        manager = Manager()
+        lock = manager.Lock()
+    tasks = {
+        asyncio.ensure_future(
+            loop.run_in_executor(
+                executor, format_file_in_place, src, fast, mode, write_back, lock
+            )
+        ): src
+        for src in sorted(sources)
+    }
+    pending: Iterable[asyncio.Future] = tasks.keys()
+    try:
+        loop.add_signal_handler(signal.SIGINT, cancel, pending)
+        loop.add_signal_handler(signal.SIGTERM, cancel, pending)
+    except NotImplementedError:
+        # There are no good alternatives for these on Windows.
+        pass
+    while pending:
+        done, _ = await asyncio.wait(pending, return_when=asyncio.FIRST_COMPLETED)
+        for task in done:
+            src = tasks.pop(task)
+            if task.cancelled():
+                cancelled.append(task)
+            elif task.exception():
+                report.failed(src, str(task.exception()))
+            else:
+                changed = Changed.YES if task.result() else Changed.NO
+                # If the file was written back or was successfully checked as
+                # well-formatted, store this information in the cache.
+                if write_back is WriteBack.YES or (
+                    write_back is WriteBack.CHECK and changed is Changed.NO
+                ):
+                    sources_to_cache.append(src)
+                report.done(src, changed)
+    if cancelled:
+        await asyncio.gather(*cancelled, loop=loop, return_exceptions=True)
+    if sources_to_cache:
+        write_cache(cache, sources_to_cache, mode)
+
+
+def format_file_in_place(
+    src: Path,
+    fast: bool,
+    mode: FileMode,
+    write_back: WriteBack = WriteBack.NO,
+    lock: Any = None,  # multiprocessing.Manager().Lock() is some crazy proxy
+) -> bool:
+    """Format file under `src` path. Return True if changed.
+
+    If `write_back` is DIFF, write a diff to stdout. If it is YES, write reformatted
+    code to the file.
+    `mode` and `fast` options are passed to :func:`format_file_contents`.
+    """
+    if src.suffix == ".pyi":
+        mode = evolve(mode, is_pyi=True)
+
+    then = datetime.utcfromtimestamp(src.stat().st_mtime)
+    with open(src, "rb") as buf:
+        src_contents, encoding, newline = decode_bytes(buf.read())
+    try:
+        dst_contents = format_file_contents(src_contents, fast=fast, mode=mode)
+    except NothingChanged:
+        return False
+
+    if write_back == write_back.YES:
+        with open(src, "w", encoding=encoding, newline=newline) as f:
+            f.write(dst_contents)
+    elif write_back == write_back.DIFF:
+        now = datetime.utcnow()
+        src_name = f"{src}\t{then} +0000"
+        dst_name = f"{src}\t{now} +0000"
+        diff_contents = diff(src_contents, dst_contents, src_name, dst_name)
+
+        with lock or nullcontext():
+            f = io.TextIOWrapper(
+                sys.stdout.buffer,
+                encoding=encoding,
+                newline=newline,
+                write_through=True,
+            )
+            f.write(diff_contents)
+            f.detach()
+
+    return True
+
+
+def format_stdin_to_stdout(
+    fast: bool, *, write_back: WriteBack = WriteBack.NO, mode: FileMode
+) -> bool:
+    """Format file on stdin. Return True if changed.
+
+    If `write_back` is YES, write reformatted code back to stdout. If it is DIFF,
+    write a diff to stdout. The `mode` argument is passed to
+    :func:`format_file_contents`.
+    """
+    then = datetime.utcnow()
+    src, encoding, newline = decode_bytes(sys.stdin.buffer.read())
+    dst = src
+    try:
+        dst = format_file_contents(src, fast=fast, mode=mode)
+        return True
+
+    except NothingChanged:
+        return False
+
+    finally:
+        f = io.TextIOWrapper(
+            sys.stdout.buffer, encoding=encoding, newline=newline, write_through=True
+        )
+        if write_back == WriteBack.YES:
+            f.write(dst)
+        elif write_back == WriteBack.DIFF:
+            now = datetime.utcnow()
+            src_name = f"STDIN\t{then} +0000"
+            dst_name = f"STDOUT\t{now} +0000"
+            f.write(diff(src, dst, src_name, dst_name))
+        f.detach()
+
+
+def format_file_contents(
+    src_contents: str, *, fast: bool, mode: FileMode
+) -> FileContent:
+    """Reformat contents a file and return new contents.
+
+    If `fast` is False, additionally confirm that the reformatted code is
+    valid by calling :func:`assert_equivalent` and :func:`assert_stable` on it.
+    `mode` is passed to :func:`format_str`.
+    """
+    if src_contents.strip() == "":
+        raise NothingChanged
+
+    dst_contents = format_str(src_contents, mode=mode)
+    if src_contents == dst_contents:
+        raise NothingChanged
+
+    if not fast:
+        assert_equivalent(src_contents, dst_contents)
+        assert_stable(src_contents, dst_contents, mode=mode)
+    return dst_contents
+
+
+def format_str(src_contents: str, *, mode: FileMode) -> FileContent:
+    """Reformat a string and return new contents.
+
+    `mode` determines formatting options, such as how many characters per line are
+    allowed.
+    """
+    src_node = lib2to3_parse(src_contents.lstrip(), mode.target_versions)
+    dst_contents = []
+    future_imports = get_future_imports(src_node)
+    if mode.target_versions:
+        versions = mode.target_versions
+    else:
+        versions = detect_target_versions(src_node)
+    normalize_fmt_off(src_node)
+    lines = LineGenerator(
+        remove_u_prefix="unicode_literals" in future_imports
+        or supports_feature(versions, Feature.UNICODE_LITERALS),
+        is_pyi=mode.is_pyi,
+        normalize_strings=mode.string_normalization,
+    )
+    elt = EmptyLineTracker(is_pyi=mode.is_pyi)
+    empty_line = Line()
+    after = 0
+    split_line_features = {
+        feature
+        for feature in {Feature.TRAILING_COMMA_IN_CALL, Feature.TRAILING_COMMA_IN_DEF}
+        if supports_feature(versions, feature)
+    }
+    for current_line in lines.visit(src_node):
+        for _ in range(after):
+            dst_contents.append(str(empty_line))
+        before, after = elt.maybe_empty_lines(current_line)
+        for _ in range(before):
+            dst_contents.append(str(empty_line))
+        for line in split_line(
+            current_line, line_length=mode.line_length, features=split_line_features
+        ):
+            dst_contents.append(str(line))
+    return "".join(dst_contents)
+
+
+def decode_bytes(src: bytes) -> Tuple[FileContent, Encoding, NewLine]:
+    """Return a tuple of (decoded_contents, encoding, newline).
+
+    `newline` is either CRLF or LF but `decoded_contents` is decoded with
+    universal newlines (i.e. only contains LF).
+    """
+    srcbuf = io.BytesIO(src)
+    encoding, lines = tokenize.detect_encoding(srcbuf.readline)
+    if not lines:
+        return "", encoding, "\n"
+
+    newline = "\r\n" if b"\r\n" == lines[0][-2:] else "\n"
+    srcbuf.seek(0)
+    with io.TextIOWrapper(srcbuf, encoding) as tiow:
+        return tiow.read(), encoding, newline
+
+
+def get_grammars(target_versions: Set[TargetVersion]) -> List[Grammar]:
+    if not target_versions:
+        # No target_version specified, so try all grammars.
+        return [
+            # Python 3.7+
+            pygram.python_grammar_no_print_statement_no_exec_statement_async_keywords,
+            # Python 3.0-3.6
+            pygram.python_grammar_no_print_statement_no_exec_statement,
+            # Python 2.7 with future print_function import
+            pygram.python_grammar_no_print_statement,
+            # Python 2.7
+            pygram.python_grammar,
+        ]
+    elif all(version.is_python2() for version in target_versions):
+        # Python 2-only code, so try Python 2 grammars.
+        return [
+            # Python 2.7 with future print_function import
+            pygram.python_grammar_no_print_statement,
+            # Python 2.7
+            pygram.python_grammar,
+        ]
+    else:
+        # Python 3-compatible code, so only try Python 3 grammar.
+        grammars = []
+        # If we have to parse both, try to parse async as a keyword first
+        if not supports_feature(target_versions, Feature.ASYNC_IDENTIFIERS):
+            # Python 3.7+
+            grammars.append(
+                pygram.python_grammar_no_print_statement_no_exec_statement_async_keywords  # noqa: B950
+            )
+        if not supports_feature(target_versions, Feature.ASYNC_KEYWORDS):
+            # Python 3.0-3.6
+            grammars.append(pygram.python_grammar_no_print_statement_no_exec_statement)
+        # At least one of the above branches must have been taken, because every Python
+        # version has exactly one of the two 'ASYNC_*' flags
+        return grammars
+
+
+def lib2to3_parse(src_txt: str, target_versions: Iterable[TargetVersion] = ()) -> Node:
+    """Given a string with source, return the lib2to3 Node."""
+    if src_txt[-1:] != "\n":
+        src_txt += "\n"
+
+    for grammar in get_grammars(set(target_versions)):
+        drv = driver.Driver(grammar, pytree.convert)
+        try:
+            result = drv.parse_string(src_txt, True)
+            break
+
+        except ParseError as pe:
+            lineno, column = pe.context[1]
+            lines = src_txt.splitlines()
+            try:
+                faulty_line = lines[lineno - 1]
+            except IndexError:
+                faulty_line = "<line number missing in source>"
+            exc = InvalidInput(f"Cannot parse: {lineno}:{column}: {faulty_line}")
+    else:
+        raise exc from None
+
+    if isinstance(result, Leaf):
+        result = Node(syms.file_input, [result])
+    return result
+
+
+def lib2to3_unparse(node: Node) -> str:
+    """Given a lib2to3 node, return its string representation."""
+    code = str(node)
+    return code
+
+
+T = TypeVar("T")
+
+
+class Visitor(Generic[T]):
+    """Basic lib2to3 visitor that yields things of type `T` on `visit()`."""
+
+    def visit(self, node: LN) -> Iterator[T]:
+        """Main method to visit `node` and its children.
+
+        It tries to find a `visit_*()` method for the given `node.type`, like
+        `visit_simple_stmt` for Node objects or `visit_INDENT` for Leaf objects.
+        If no dedicated `visit_*()` method is found, chooses `visit_default()`
+        instead.
+
+        Then yields objects of type `T` from the selected visitor.
+        """
+        if node.type < 256:
+            name = token.tok_name[node.type]
+        else:
+            name = type_repr(node.type)
+        yield from getattr(self, f"visit_{name}", self.visit_default)(node)
+
+    def visit_default(self, node: LN) -> Iterator[T]:
+        """Default `visit_*()` implementation. Recurses to children of `node`."""
+        if isinstance(node, Node):
+            for child in node.children:
+                yield from self.visit(child)
+
+
+@dataclass
+class DebugVisitor(Visitor[T]):
+    tree_depth: int = 0
+
+    def visit_default(self, node: LN) -> Iterator[T]:
+        indent = " " * (2 * self.tree_depth)
+        if isinstance(node, Node):
+            _type = type_repr(node.type)
+            out(f"{indent}{_type}", fg="yellow")
+            self.tree_depth += 1
+            for child in node.children:
+                yield from self.visit(child)
+
+            self.tree_depth -= 1
+            out(f"{indent}/{_type}", fg="yellow", bold=False)
+        else:
+            _type = token.tok_name.get(node.type, str(node.type))
+            out(f"{indent}{_type}", fg="blue", nl=False)
+            if node.prefix:
+                # We don't have to handle prefixes for `Node` objects since
+                # that delegates to the first child anyway.
+                out(f" {node.prefix!r}", fg="green", bold=False, nl=False)
+            out(f" {node.value!r}", fg="blue", bold=False)
+
+    @classmethod
+    def show(cls, code: Union[str, Leaf, Node]) -> None:
+        """Pretty-print the lib2to3 AST of a given string of `code`.
+
+        Convenience method for debugging.
+        """
+        v: DebugVisitor[None] = DebugVisitor()
+        if isinstance(code, str):
+            code = lib2to3_parse(code)
+        list(v.visit(code))
+
+
+WHITESPACE = {token.DEDENT, token.INDENT, token.NEWLINE}
+STATEMENT = {
+    syms.if_stmt,
+    syms.while_stmt,
+    syms.for_stmt,
+    syms.try_stmt,
+    syms.except_clause,
+    syms.with_stmt,
+    syms.funcdef,
+    syms.classdef,
+}
+STANDALONE_COMMENT = 153
+token.tok_name[STANDALONE_COMMENT] = "STANDALONE_COMMENT"
+LOGIC_OPERATORS = {"and", "or"}
+COMPARATORS = {
+    token.LESS,
+    token.GREATER,
+    token.EQEQUAL,
+    token.NOTEQUAL,
+    token.LESSEQUAL,
+    token.GREATEREQUAL,
+}
+MATH_OPERATORS = {
+    token.VBAR,
+    token.CIRCUMFLEX,
+    token.AMPER,
+    token.LEFTSHIFT,
+    token.RIGHTSHIFT,
+    token.PLUS,
+    token.MINUS,
+    token.STAR,
+    token.SLASH,
+    token.DOUBLESLASH,
+    token.PERCENT,
+    token.AT,
+    token.TILDE,
+    token.DOUBLESTAR,
+}
+STARS = {token.STAR, token.DOUBLESTAR}
+VARARGS_SPECIALS = STARS | {token.SLASH}
+VARARGS_PARENTS = {
+    syms.arglist,
+    syms.argument,  # double star in arglist
+    syms.trailer,  # single argument to call
+    syms.typedargslist,
+    syms.varargslist,  # lambdas
+}
+UNPACKING_PARENTS = {
+    syms.atom,  # single element of a list or set literal
+    syms.dictsetmaker,
+    syms.listmaker,
+    syms.testlist_gexp,
+    syms.testlist_star_expr,
+}
+TEST_DESCENDANTS = {
+    syms.test,
+    syms.lambdef,
+    syms.or_test,
+    syms.and_test,
+    syms.not_test,
+    syms.comparison,
+    syms.star_expr,
+    syms.expr,
+    syms.xor_expr,
+    syms.and_expr,
+    syms.shift_expr,
+    syms.arith_expr,
+    syms.trailer,
+    syms.term,
+    syms.power,
+}
+ASSIGNMENTS = {
+    "=",
+    "+=",
+    "-=",
+    "*=",
+    "@=",
+    "/=",
+    "%=",
+    "&=",
+    "|=",
+    "^=",
+    "<<=",
+    ">>=",
+    "**=",
+    "//=",
+}
+COMPREHENSION_PRIORITY = 20
+COMMA_PRIORITY = 18
+TERNARY_PRIORITY = 16
+LOGIC_PRIORITY = 14
+STRING_PRIORITY = 12
+COMPARATOR_PRIORITY = 10
+MATH_PRIORITIES = {
+    token.VBAR: 9,
+    token.CIRCUMFLEX: 8,
+    token.AMPER: 7,
+    token.LEFTSHIFT: 6,
+    token.RIGHTSHIFT: 6,
+    token.PLUS: 5,
+    token.MINUS: 5,
+    token.STAR: 4,
+    token.SLASH: 4,
+    token.DOUBLESLASH: 4,
+    token.PERCENT: 4,
+    token.AT: 4,
+    token.TILDE: 3,
+    token.DOUBLESTAR: 2,
+}
+DOT_PRIORITY = 1
+
+
+@dataclass
+class BracketTracker:
+    """Keeps track of brackets on a line."""
+
+    depth: int = 0
+    bracket_match: Dict[Tuple[Depth, NodeType], Leaf] = Factory(dict)
+    delimiters: Dict[LeafID, Priority] = Factory(dict)
+    previous: Optional[Leaf] = None
+    _for_loop_depths: List[int] = Factory(list)
+    _lambda_argument_depths: List[int] = Factory(list)
+
+    def mark(self, leaf: Leaf) -> None:
+        """Mark `leaf` with bracket-related metadata. Keep track of delimiters.
+
+        All leaves receive an int `bracket_depth` field that stores how deep
+        within brackets a given leaf is. 0 means there are no enclosing brackets
+        that started on this line.
+
+        If a leaf is itself a closing bracket, it receives an `opening_bracket`
+        field that it forms a pair with. This is a one-directional link to
+        avoid reference cycles.
+
+        If a leaf is a delimiter (a token on which Black can split the line if
+        needed) and it's on depth 0, its `id()` is stored in the tracker's
+        `delimiters` field.
+        """
+        if leaf.type == token.COMMENT:
+            return
+
+        self.maybe_decrement_after_for_loop_variable(leaf)
+        self.maybe_decrement_after_lambda_arguments(leaf)
+        if leaf.type in CLOSING_BRACKETS:
+            self.depth -= 1
+            opening_bracket = self.bracket_match.pop((self.depth, leaf.type))
+            leaf.opening_bracket = opening_bracket
+        leaf.bracket_depth = self.depth
+        if self.depth == 0:
+            delim = is_split_before_delimiter(leaf, self.previous)
+            if delim and self.previous is not None:
+                self.delimiters[id(self.previous)] = delim
+            else:
+                delim = is_split_after_delimiter(leaf, self.previous)
+                if delim:
+                    self.delimiters[id(leaf)] = delim
+        if leaf.type in OPENING_BRACKETS:
+            self.bracket_match[self.depth, BRACKET[leaf.type]] = leaf
+            self.depth += 1
+        self.previous = leaf
+        self.maybe_increment_lambda_arguments(leaf)
+        self.maybe_increment_for_loop_variable(leaf)
+
+    def any_open_brackets(self) -> bool:
+        """Return True if there is an yet unmatched open bracket on the line."""
+        return bool(self.bracket_match)
+
+    def max_delimiter_priority(self, exclude: Iterable[LeafID] = ()) -> Priority:
+        """Return the highest priority of a delimiter found on the line.
+
+        Values are consistent with what `is_split_*_delimiter()` return.
+        Raises ValueError on no delimiters.
+        """
+        return max(v for k, v in self.delimiters.items() if k not in exclude)
+
+    def delimiter_count_with_priority(self, priority: Priority = 0) -> int:
+        """Return the number of delimiters with the given `priority`.
+
+        If no `priority` is passed, defaults to max priority on the line.
+        """
+        if not self.delimiters:
+            return 0
+
+        priority = priority or self.max_delimiter_priority()
+        return sum(1 for p in self.delimiters.values() if p == priority)
+
+    def maybe_increment_for_loop_variable(self, leaf: Leaf) -> bool:
+        """In a for loop, or comprehension, the variables are often unpacks.
+
+        To avoid splitting on the comma in this situation, increase the depth of
+        tokens between `for` and `in`.
+        """
+        if leaf.type == token.NAME and leaf.value == "for":
+            self.depth += 1
+            self._for_loop_depths.append(self.depth)
+            return True
+
+        return False
+
+    def maybe_decrement_after_for_loop_variable(self, leaf: Leaf) -> bool:
+        """See `maybe_increment_for_loop_variable` above for explanation."""
+        if (
+            self._for_loop_depths
+            and self._for_loop_depths[-1] == self.depth
+            and leaf.type == token.NAME
+            and leaf.value == "in"
+        ):
+            self.depth -= 1
+            self._for_loop_depths.pop()
+            return True
+
+        return False
+
+    def maybe_increment_lambda_arguments(self, leaf: Leaf) -> bool:
+        """In a lambda expression, there might be more than one argument.
+
+        To avoid splitting on the comma in this situation, increase the depth of
+        tokens between `lambda` and `:`.
+        """
+        if leaf.type == token.NAME and leaf.value == "lambda":
+            self.depth += 1
+            self._lambda_argument_depths.append(self.depth)
+            return True
+
+        return False
+
+    def maybe_decrement_after_lambda_arguments(self, leaf: Leaf) -> bool:
+        """See `maybe_increment_lambda_arguments` above for explanation."""
+        if (
+            self._lambda_argument_depths
+            and self._lambda_argument_depths[-1] == self.depth
+            and leaf.type == token.COLON
+        ):
+            self.depth -= 1
+            self._lambda_argument_depths.pop()
+            return True
+
+        return False
+
+    def get_open_lsqb(self) -> Optional[Leaf]:
+        """Return the most recent opening square bracket (if any)."""
+        return self.bracket_match.get((self.depth - 1, token.RSQB))
+
+
+@dataclass
+class Line:
+    """Holds leaves and comments. Can be printed with `str(line)`."""
+
+    depth: int = 0
+    leaves: List[Leaf] = Factory(list)
+    comments: Dict[LeafID, List[Leaf]] = Factory(dict)  # keys ordered like `leaves`
+    bracket_tracker: BracketTracker = Factory(BracketTracker)
+    inside_brackets: bool = False
+    should_explode: bool = False
+
+    def append(self, leaf: Leaf, preformatted: bool = False) -> None:
+        """Add a new `leaf` to the end of the line.
+
+        Unless `preformatted` is True, the `leaf` will receive a new consistent
+        whitespace prefix and metadata applied by :class:`BracketTracker`.
+        Trailing commas are maybe removed, unpacked for loop variables are
+        demoted from being delimiters.
+
+        Inline comments are put aside.
+        """
+        has_value = leaf.type in BRACKETS or bool(leaf.value.strip())
+        if not has_value:
+            return
+
+        if token.COLON == leaf.type and self.is_class_paren_empty:
+            del self.leaves[-2:]
+        if self.leaves and not preformatted:
+            # Note: at this point leaf.prefix should be empty except for
+            # imports, for which we only preserve newlines.
+            leaf.prefix += whitespace(
+                leaf, complex_subscript=self.is_complex_subscript(leaf)
+            )
+        if self.inside_brackets or not preformatted:
+            self.bracket_tracker.mark(leaf)
+            self.maybe_remove_trailing_comma(leaf)
+        if not self.append_comment(leaf):
+            self.leaves.append(leaf)
+
+    def append_safe(self, leaf: Leaf, preformatted: bool = False) -> None:
+        """Like :func:`append()` but disallow invalid standalone comment structure.
+
+        Raises ValueError when any `leaf` is appended after a standalone comment
+        or when a standalone comment is not the first leaf on the line.
+        """
+        if self.bracket_tracker.depth == 0:
+            if self.is_comment:
+                raise ValueError("cannot append to standalone comments")
+
+            if self.leaves and leaf.type == STANDALONE_COMMENT:
+                raise ValueError(
+                    "cannot append standalone comments to a populated line"
+                )
+
+        self.append(leaf, preformatted=preformatted)
+
+    @property
+    def is_comment(self) -> bool:
+        """Is this line a standalone comment?"""
+        return len(self.leaves) == 1 and self.leaves[0].type == STANDALONE_COMMENT
+
+    @property
+    def is_decorator(self) -> bool:
+        """Is this line a decorator?"""
+        return bool(self) and self.leaves[0].type == token.AT
+
+    @property
+    def is_import(self) -> bool:
+        """Is this an import line?"""
+        return bool(self) and is_import(self.leaves[0])
+
+    @property
+    def is_class(self) -> bool:
+        """Is this line a class definition?"""
+        return (
+            bool(self)
+            and self.leaves[0].type == token.NAME
+            and self.leaves[0].value == "class"
+        )
+
+    @property
+    def is_stub_class(self) -> bool:
+        """Is this line a class definition with a body consisting only of "..."?"""
+        return self.is_class and self.leaves[-3:] == [
+            Leaf(token.DOT, ".") for _ in range(3)
+        ]
+
+    @property
+    def is_collection_with_optional_trailing_comma(self) -> bool:
+        """Is this line a collection literal with a trailing comma that's optional?
+
+        Note that the trailing comma in a 1-tuple is not optional.
+        """
+        if not self.leaves or len(self.leaves) < 4:
+            return False
+        # Look for and address a trailing colon.
+        if self.leaves[-1].type == token.COLON:
+            closer = self.leaves[-2]
+            close_index = -2
+        else:
+            closer = self.leaves[-1]
+            close_index = -1
+        if closer.type not in CLOSING_BRACKETS or self.inside_brackets:
+            return False
+        if closer.type == token.RPAR:
+            # Tuples require an extra check, because if there's only
+            # one element in the tuple removing the comma unmakes the
+            # tuple.
+            #
+            # We also check for parens before looking for the trailing
+            # comma because in some cases (eg assigning a dict
+            # literal) the literal gets wrapped in temporary parens
+            # during parsing. This case is covered by the
+            # collections.py test data.
+            opener = closer.opening_bracket
+            for _open_index, leaf in enumerate(self.leaves):
+                if leaf is opener:
+                    break
+            else:
+                # Couldn't find the matching opening paren, play it safe.
+                return False
+            commas = 0
+            comma_depth = self.leaves[close_index - 1].bracket_depth
+            for leaf in self.leaves[_open_index + 1 : close_index]:
+                if leaf.bracket_depth == comma_depth and leaf.type == token.COMMA:
+                    commas += 1
+            if commas > 1:
+                # We haven't looked yet for the trailing comma because
+                # we might also have caught noop parens.
+                return self.leaves[close_index - 1].type == token.COMMA
+            elif commas == 1:
+                return False  # it's either a one-tuple or didn't have a trailing comma
+            if self.leaves[close_index - 1].type in CLOSING_BRACKETS:
+                close_index -= 1
+                closer = self.leaves[close_index]
+                if closer.type == token.RPAR:
+                    # TODO: this is a gut feeling. Will we ever see this?
+                    return False
+        if self.leaves[close_index - 1].type != token.COMMA:
+            return False
+        return True
+
+    @property
+    def is_def(self) -> bool:
+        """Is this a function definition? (Also returns True for async defs.)"""
+        try:
+            first_leaf = self.leaves[0]
+        except IndexError:
+            return False
+
+        try:
+            second_leaf: Optional[Leaf] = self.leaves[1]
+        except IndexError:
+            second_leaf = None
+        return (first_leaf.type == token.NAME and first_leaf.value == "def") or (
+            first_leaf.type == token.ASYNC
+            and second_leaf is not None
+            and second_leaf.type == token.NAME
+            and second_leaf.value == "def"
+        )
+
+    @property
+    def is_class_paren_empty(self) -> bool:
+        """Is this a class with no base classes but using parentheses?
+
+        Those are unnecessary and should be removed.
+        """
+        return (
+            bool(self)
+            and len(self.leaves) == 4
+            and self.is_class
+            and self.leaves[2].type == token.LPAR
+            and self.leaves[2].value == "("
+            and self.leaves[3].type == token.RPAR
+            and self.leaves[3].value == ")"
+        )
+
+    @property
+    def is_triple_quoted_string(self) -> bool:
+        """Is the line a triple quoted string?"""
+        return (
+            bool(self)
+            and self.leaves[0].type == token.STRING
+            and self.leaves[0].value.startswith(('"""', "'''"))
+        )
+
+    def contains_standalone_comments(self, depth_limit: int = sys.maxsize) -> bool:
+        """If so, needs to be split before emitting."""
+        for leaf in self.leaves:
+            if leaf.type == STANDALONE_COMMENT:
+                if leaf.bracket_depth <= depth_limit:
+                    return True
+        return False
+
+    def contains_uncollapsable_type_comments(self) -> bool:
+        ignored_ids = set()
+        try:
+            last_leaf = self.leaves[-1]
+            ignored_ids.add(id(last_leaf))
+            if last_leaf.type == token.COMMA or (
+                last_leaf.type == token.RPAR and not last_leaf.value
+            ):
+                # When trailing commas or optional parens are inserted by Black for
+                # consistency, comments after the previous last element are not moved
+                # (they don't have to, rendering will still be correct).  So we ignore
+                # trailing commas and invisible.
+                last_leaf = self.leaves[-2]
+                ignored_ids.add(id(last_leaf))
+        except IndexError:
+            return False
+
+        # A type comment is uncollapsable if it is attached to a leaf
+        # that isn't at the end of the line (since that could cause it
+        # to get associated to a different argument) or if there are
+        # comments before it (since that could cause it to get hidden
+        # behind a comment.
+        comment_seen = False
+        for leaf_id, comments in self.comments.items():
+            for comment in comments:
+                if is_type_comment(comment):
+                    if leaf_id not in ignored_ids or comment_seen:
+                        return True
+
+            comment_seen = True
+
+        return False
+
+    def contains_unsplittable_type_ignore(self) -> bool:
+        if not self.leaves:
+            return False
+
+        # If a 'type: ignore' is attached to the end of a line, we
+        # can't split the line, because we can't know which of the
+        # subexpressions the ignore was meant to apply to.
+        #
+        # We only want this to apply to actual physical lines from the
+        # original source, though: we don't want the presence of a
+        # 'type: ignore' at the end of a multiline expression to
+        # justify pushing it all onto one line. Thus we
+        # (unfortunately) need to check the actual source lines and
+        # only report an unsplittable 'type: ignore' if this line was
+        # one line in the original code.
+        if self.leaves[0].lineno == self.leaves[-1].lineno:
+            for comment in self.comments.get(id(self.leaves[-1]), []):
+                if is_type_comment(comment, " ignore"):
+                    return True
+
+        return False
+
+    def contains_multiline_strings(self) -> bool:
+        for leaf in self.leaves:
+            if is_multiline_string(leaf):
+                return True
+
+        return False
+
+    def maybe_remove_trailing_comma(self, closing: Leaf) -> bool:
+        """Remove trailing comma if there is one and it's safe."""
+        if not (self.leaves and self.leaves[-1].type == token.COMMA):
+            return False
+        # We remove trailing commas only in the case of importing a
+        # single name from a module.
+        if not (
+            self.leaves
+            and self.is_import
+            and len(self.leaves) > 4
+            and self.leaves[-1].type == token.COMMA
+            and closing.type in CLOSING_BRACKETS
+            and self.leaves[-4].type == token.NAME
+            and (
+                # regular `from foo import bar,`
+                self.leaves[-4].value == "import"
+                # `from foo import (bar as baz,)
+                or (
+                    len(self.leaves) > 6
+                    and self.leaves[-6].value == "import"
+                    and self.leaves[-3].value == "as"
+                )
+                # `from foo import bar as baz,`
+                or (
+                    len(self.leaves) > 5
+                    and self.leaves[-5].value == "import"
+                    and self.leaves[-3].value == "as"
+                )
+            )
+            and closing.type == token.RPAR
+        ):
+            return False
+
+        self.remove_trailing_comma()
+        return True
+
+    def append_comment(self, comment: Leaf) -> bool:
+        """Add an inline or standalone comment to the line."""
+        if (
+            comment.type == STANDALONE_COMMENT
+            and self.bracket_tracker.any_open_brackets()
+        ):
+            comment.prefix = ""
+            return False
+
+        if comment.type != token.COMMENT:
+            return False
+
+        if not self.leaves:
+            comment.type = STANDALONE_COMMENT
+            comment.prefix = ""
+            return False
+
+        last_leaf = self.leaves[-1]
+        if (
+            last_leaf.type == token.RPAR
+            and not last_leaf.value
+            and last_leaf.parent
+            and len(list(last_leaf.parent.leaves())) <= 3
+            and not is_type_comment(comment)
+        ):
+            # Comments on an optional parens wrapping a single leaf should belong to
+            # the wrapped node except if it's a type comment. Pinning the comment like
+            # this avoids unstable formatting caused by comment migration.
+            if len(self.leaves) < 2:
+                comment.type = STANDALONE_COMMENT
+                comment.prefix = ""
+                return False
+            last_leaf = self.leaves[-2]
+        self.comments.setdefault(id(last_leaf), []).append(comment)
+        return True
+
+    def comments_after(self, leaf: Leaf) -> List[Leaf]:
+        """Generate comments that should appear directly after `leaf`."""
+        return self.comments.get(id(leaf), [])
+
+    def remove_trailing_comma(self) -> None:
+        """Remove the trailing comma and moves the comments attached to it."""
+        trailing_comma = self.leaves.pop()
+        trailing_comma_comments = self.comments.pop(id(trailing_comma), [])
+        self.comments.setdefault(id(self.leaves[-1]), []).extend(
+            trailing_comma_comments
+        )
+
+    def is_complex_subscript(self, leaf: Leaf) -> bool:
+        """Return True iff `leaf` is part of a slice with non-trivial exprs."""
+        open_lsqb = self.bracket_tracker.get_open_lsqb()
+        if open_lsqb is None:
+            return False
+
+        subscript_start = open_lsqb.next_sibling
+
+        if isinstance(subscript_start, Node):
+            if subscript_start.type == syms.listmaker:
+                return False
+
+            if subscript_start.type == syms.subscriptlist:
+                subscript_start = child_towards(subscript_start, leaf)
+        return subscript_start is not None and any(
+            n.type in TEST_DESCENDANTS for n in subscript_start.pre_order()
+        )
+
+    def __str__(self) -> str:
+        """Render the line."""
+        if not self:
+            return "\n"
+
+        indent = "    " * self.depth
+        leaves = iter(self.leaves)
+        first = next(leaves)
+        res = f"{first.prefix}{indent}{first.value}"
+        for leaf in leaves:
+            res += str(leaf)
+        for comment in itertools.chain.from_iterable(self.comments.values()):
+            res += str(comment)
+        return res + "\n"
+
+    def __bool__(self) -> bool:
+        """Return True if the line has leaves or comments."""
+        return bool(self.leaves or self.comments)
+
+
+@dataclass
+class EmptyLineTracker:
+    """Provides a stateful method that returns the number of potential extra
+    empty lines needed before and after the currently processed line.
+
+    Note: this tracker works on lines that haven't been split yet.  It assumes
+    the prefix of the first leaf consists of optional newlines.  Those newlines
+    are consumed by `maybe_empty_lines()` and included in the computation.
+    """
+
+    is_pyi: bool = False
+    previous_line: Optional[Line] = None
+    previous_after: int = 0
+    previous_defs: List[int] = Factory(list)
+
+    def maybe_empty_lines(self, current_line: Line) -> Tuple[int, int]:
+        """Return the number of extra empty lines before and after the `current_line`.
+
+        This is for separating `def`, `async def` and `class` with extra empty
+        lines (two on module-level).
+        """
+        before, after = self._maybe_empty_lines(current_line)
+        before = (
+            # Black should not insert empty lines at the beginning
+            # of the file
+            0
+            if self.previous_line is None
+            else before - self.previous_after
+        )
+        self.previous_after = after
+        self.previous_line = current_line
+        return before, after
+
+    def _maybe_empty_lines(self, current_line: Line) -> Tuple[int, int]:
+        max_allowed = 1
+        if current_line.depth == 0:
+            max_allowed = 1 if self.is_pyi else 2
+        if current_line.leaves:
+            # Consume the first leaf's extra newlines.
+            first_leaf = current_line.leaves[0]
+            before = first_leaf.prefix.count("\n")
+            before = min(before, max_allowed)
+            first_leaf.prefix = ""
+        else:
+            before = 0
+        depth = current_line.depth
+        while self.previous_defs and self.previous_defs[-1] >= depth:
+            self.previous_defs.pop()
+            if self.is_pyi:
+                before = 0 if depth else 1
+            else:
+                before = 1 if depth else 2
+        if current_line.is_decorator or current_line.is_def or current_line.is_class:
+            return self._maybe_empty_lines_for_class_or_def(current_line, before)
+
+        if (
+            self.previous_line
+            and self.previous_line.is_import
+            and not current_line.is_import
+            and depth == self.previous_line.depth
+        ):
+            return (before or 1), 0
+
+        if (
+            self.previous_line
+            and self.previous_line.is_class
+            and current_line.is_triple_quoted_string
+        ):
+            return before, 1
+
+        return before, 0
+
+    def _maybe_empty_lines_for_class_or_def(
+        self, current_line: Line, before: int
+    ) -> Tuple[int, int]:
+        if not current_line.is_decorator:
+            self.previous_defs.append(current_line.depth)
+        if self.previous_line is None:
+            # Don't insert empty lines before the first line in the file.
+            return 0, 0
+
+        if self.previous_line.is_decorator:
+            return 0, 0
+
+        if self.previous_line.depth < current_line.depth and (
+            self.previous_line.is_class or self.previous_line.is_def
+        ):
+            return 0, 0
+
+        if (
+            self.previous_line.is_comment
+            and self.previous_line.depth == current_line.depth
+            and before == 0
+        ):
+            return 0, 0
+
+        if self.is_pyi:
+            if self.previous_line.depth > current_line.depth:
+                newlines = 1
+            elif current_line.is_class or self.previous_line.is_class:
+                if current_line.is_stub_class and self.previous_line.is_stub_class:
+                    # No blank line between classes with an empty body
+                    newlines = 0
+                else:
+                    newlines = 1
+            elif current_line.is_def and not self.previous_line.is_def:
+                # Blank line between a block of functions and a block of non-functions
+                newlines = 1
+            else:
+                newlines = 0
+        else:
+            newlines = 2
+        if current_line.depth and newlines:
+            newlines -= 1
+        return newlines, 0
+
+
+@dataclass
+class LineGenerator(Visitor[Line]):
+    """Generates reformatted Line objects.  Empty lines are not emitted.
+
+    Note: destroys the tree it's visiting by mutating prefixes of its leaves
+    in ways that will no longer stringify to valid Python code on the tree.
+    """
+
+    is_pyi: bool = False
+    normalize_strings: bool = True
+    current_line: Line = Factory(Line)
+    remove_u_prefix: bool = False
+
+    def line(self, indent: int = 0) -> Iterator[Line]:
+        """Generate a line.
+
+        If the line is empty, only emit if it makes sense.
+        If the line is too long, split it first and then generate.
+
+        If any lines were generated, set up a new current_line.
+        """
+        if not self.current_line:
+            self.current_line.depth += indent
+            return  # Line is empty, don't emit. Creating a new one unnecessary.
+
+        complete_line = self.current_line
+        self.current_line = Line(depth=complete_line.depth + indent)
+        yield complete_line
+
+    def visit_default(self, node: LN) -> Iterator[Line]:
+        """Default `visit_*()` implementation. Recurses to children of `node`."""
+        if isinstance(node, Leaf):
+            any_open_brackets = self.current_line.bracket_tracker.any_open_brackets()
+            for comment in generate_comments(node):
+                if any_open_brackets:
+                    # any comment within brackets is subject to splitting
+                    self.current_line.append(comment)
+                elif comment.type == token.COMMENT:
+                    # regular trailing comment
+                    self.current_line.append(comment)
+                    yield from self.line()
+
+                else:
+                    # regular standalone comment
+                    yield from self.line()
+
+                    self.current_line.append(comment)
+                    yield from self.line()
+
+            normalize_prefix(node, inside_brackets=any_open_brackets)
+            if self.normalize_strings and node.type == token.STRING:
+                normalize_string_prefix(node, remove_u_prefix=self.remove_u_prefix)
+                normalize_string_quotes(node)
+            if node.type == token.NUMBER:
+                normalize_numeric_literal(node)
+            if node.type not in WHITESPACE:
+                self.current_line.append(node)
+        yield from super().visit_default(node)
+
+    def visit_atom(self, node: Node) -> Iterator[Line]:
+        # Always make parentheses invisible around a single node, because it should
+        # not be needed (except in the case of yield, where removing the parentheses
+        # produces a SyntaxError).
+        if (
+            len(node.children) == 3
+            and isinstance(node.children[0], Leaf)
+            and node.children[0].type == token.LPAR
+            and isinstance(node.children[2], Leaf)
+            and node.children[2].type == token.RPAR
+            and isinstance(node.children[1], Leaf)
+            and not (
+                node.children[1].type == token.NAME
+                and node.children[1].value == "yield"
+            )
+        ):
+            node.children[0].value = ""
+            node.children[2].value = ""
+        yield from super().visit_default(node)
+
+    def visit_factor(self, node: Node) -> Iterator[Line]:
+        """Force parentheses between a unary op and a binary power:
+
+        -2 ** 8 -> -(2 ** 8)
+        """
+        child = node.children[1]
+        if child.type == syms.power and len(child.children) == 3:
+            lpar = Leaf(token.LPAR, "(")
+            rpar = Leaf(token.RPAR, ")")
+            index = child.remove() or 0
+            node.insert_child(index, Node(syms.atom, [lpar, child, rpar]))
+        yield from self.visit_default(node)
+
+    def visit_INDENT(self, node: Node) -> Iterator[Line]:
+        """Increase indentation level, maybe yield a line."""
+        # In blib2to3 INDENT never holds comments.
+        yield from self.line(+1)
+        yield from self.visit_default(node)
+
+    def visit_DEDENT(self, node: Node) -> Iterator[Line]:
+        """Decrease indentation level, maybe yield a line."""
+        # The current line might still wait for trailing comments.  At DEDENT time
+        # there won't be any (they would be prefixes on the preceding NEWLINE).
+        # Emit the line then.
+        yield from self.line()
+
+        # While DEDENT has no value, its prefix may contain standalone comments
+        # that belong to the current indentation level.  Get 'em.
+        yield from self.visit_default(node)
+
+        # Finally, emit the dedent.
+        yield from self.line(-1)
+
+    def visit_stmt(
+        self, node: Node, keywords: Set[str], parens: Set[str]
+    ) -> Iterator[Line]:
+        """Visit a statement.
+
+        This implementation is shared for `if`, `while`, `for`, `try`, `except`,
+        `def`, `with`, `class`, `assert` and assignments.
+
+        The relevant Python language `keywords` for a given statement will be
+        NAME leaves within it. This methods puts those on a separate line.
+
+        `parens` holds a set of string leaf values immediately after which
+        invisible parens should be put.
+        """
+        normalize_invisible_parens(node, parens_after=parens)
+        for child in node.children:
+            if child.type == token.NAME and child.value in keywords:  # type: ignore
+                yield from self.line()
+
+            yield from self.visit(child)
+
+    def visit_suite(self, node: Node) -> Iterator[Line]:
+        """Visit a suite."""
+        if self.is_pyi and is_stub_suite(node):
+            yield from self.visit(node.children[2])
+        else:
+            yield from self.visit_default(node)
+
+    def visit_simple_stmt(self, node: Node) -> Iterator[Line]:
+        """Visit a statement without nested statements."""
+        is_suite_like = node.parent and node.parent.type in STATEMENT
+        if is_suite_like:
+            if self.is_pyi and is_stub_body(node):
+                yield from self.visit_default(node)
+            else:
+                yield from self.line(+1)
+                yield from self.visit_default(node)
+                yield from self.line(-1)
+
+        else:
+            if not self.is_pyi or not node.parent or not is_stub_suite(node.parent):
+                yield from self.line()
+            yield from self.visit_default(node)
+
+    def visit_async_stmt(self, node: Node) -> Iterator[Line]:
+        """Visit `async def`, `async for`, `async with`."""
+        yield from self.line()
+
+        children = iter(node.children)
+        for child in children:
+            yield from self.visit(child)
+
+            if child.type == token.ASYNC:
+                break
+
+        internal_stmt = next(children)
+        for child in internal_stmt.children:
+            yield from self.visit(child)
+
+    def visit_decorators(self, node: Node) -> Iterator[Line]:
+        """Visit decorators."""
+        for child in node.children:
+            yield from self.line()
+            yield from self.visit(child)
+
+    def visit_SEMI(self, leaf: Leaf) -> Iterator[Line]:
+        """Remove a semicolon and put the other statement on a separate line."""
+        yield from self.line()
+
+    def visit_ENDMARKER(self, leaf: Leaf) -> Iterator[Line]:
+        """End of file. Process outstanding comments and end with a newline."""
+        yield from self.visit_default(leaf)
+        yield from self.line()
+
+    def visit_STANDALONE_COMMENT(self, leaf: Leaf) -> Iterator[Line]:
+        if not self.current_line.bracket_tracker.any_open_brackets():
+            yield from self.line()
+        yield from self.visit_default(leaf)
+
+    def __attrs_post_init__(self) -> None:
+        """You are in a twisty little maze of passages."""
+        v = self.visit_stmt
+        Ø: Set[str] = set()
+        self.visit_assert_stmt = partial(v, keywords={"assert"}, parens={"assert", ","})
+        self.visit_if_stmt = partial(
+            v, keywords={"if", "else", "elif"}, parens={"if", "elif"}
+        )
+        self.visit_while_stmt = partial(v, keywords={"while", "else"}, parens={"while"})
+        self.visit_for_stmt = partial(v, keywords={"for", "else"}, parens={"for", "in"})
+        self.visit_try_stmt = partial(
+            v, keywords={"try", "except", "else", "finally"}, parens=Ø
+        )
+        self.visit_except_clause = partial(v, keywords={"except"}, parens=Ø)
+        self.visit_with_stmt = partial(v, keywords={"with"}, parens=Ø)
+        self.visit_funcdef = partial(v, keywords={"def"}, parens=Ø)
+        self.visit_classdef = partial(v, keywords={"class"}, parens=Ø)
+        self.visit_expr_stmt = partial(v, keywords=Ø, parens=ASSIGNMENTS)
+        self.visit_return_stmt = partial(v, keywords={"return"}, parens={"return"})
+        self.visit_import_from = partial(v, keywords=Ø, parens={"import"})
+        self.visit_del_stmt = partial(v, keywords=Ø, parens={"del"})
+        self.visit_async_funcdef = self.visit_async_stmt
+        self.visit_decorated = self.visit_decorators
+
+
+IMPLICIT_TUPLE = {syms.testlist, syms.testlist_star_expr, syms.exprlist}
+BRACKET = {token.LPAR: token.RPAR, token.LSQB: token.RSQB, token.LBRACE: token.RBRACE}
+OPENING_BRACKETS = set(BRACKET.keys())
+CLOSING_BRACKETS = set(BRACKET.values())
+BRACKETS = OPENING_BRACKETS | CLOSING_BRACKETS
+ALWAYS_NO_SPACE = CLOSING_BRACKETS | {token.COMMA, STANDALONE_COMMENT}
+
+
+def whitespace(leaf: Leaf, *, complex_subscript: bool) -> str:  # noqa: C901
+    """Return whitespace prefix if needed for the given `leaf`.
+
+    `complex_subscript` signals whether the given leaf is part of a subscription
+    which has non-trivial arguments, like arithmetic expressions or function calls.
+    """
+    NO = ""
+    SPACE = " "
+    DOUBLESPACE = "  "
+    t = leaf.type
+    p = leaf.parent
+    v = leaf.value
+    if t in ALWAYS_NO_SPACE:
+        return NO
+
+    if t == token.COMMENT:
+        return DOUBLESPACE
+
+    assert p is not None, f"INTERNAL ERROR: hand-made leaf without parent: {leaf!r}"
+    if t == token.COLON and p.type not in {
+        syms.subscript,
+        syms.subscriptlist,
+        syms.sliceop,
+    }:
+        return NO
+
+    prev = leaf.prev_sibling
+    if not prev:
+        prevp = preceding_leaf(p)
+        if not prevp or prevp.type in OPENING_BRACKETS:
+            return NO
+
+        if t == token.COLON:
+            if prevp.type == token.COLON:
+                return NO
+
+            elif prevp.type != token.COMMA and not complex_subscript:
+                return NO
+
+            return SPACE
+
+        if prevp.type == token.EQUAL:
+            if prevp.parent:
+                if prevp.parent.type in {
+                    syms.arglist,
+                    syms.argument,
+                    syms.parameters,
+                    syms.varargslist,
+                }:
+                    return NO
+
+                elif prevp.parent.type == syms.typedargslist:
+                    # A bit hacky: if the equal sign has whitespace, it means we
+                    # previously found it's a typed argument.  So, we're using
+                    # that, too.
+                    return prevp.prefix
+
+        elif prevp.type in VARARGS_SPECIALS:
+            if is_vararg(prevp, within=VARARGS_PARENTS | UNPACKING_PARENTS):
+                return NO
+
+        elif prevp.type == token.COLON:
+            if prevp.parent and prevp.parent.type in {syms.subscript, syms.sliceop}:
+                return SPACE if complex_subscript else NO
+
+        elif (
+            prevp.parent
+            and prevp.parent.type == syms.factor
+            and prevp.type in MATH_OPERATORS
+        ):
+            return NO
+
+        elif (
+            prevp.type == token.RIGHTSHIFT
+            and prevp.parent
+            and prevp.parent.type == syms.shift_expr
+            and prevp.prev_sibling
+            and prevp.prev_sibling.type == token.NAME
+            and prevp.prev_sibling.value == "print"  # type: ignore
+        ):
+            # Python 2 print chevron
+            return NO
+
+    elif prev.type in OPENING_BRACKETS:
+        return NO
+
+    if p.type in {syms.parameters, syms.arglist}:
+        # untyped function signatures or calls
+        if not prev or prev.type != token.COMMA:
+            return NO
+
+    elif p.type == syms.varargslist:
+        # lambdas
+        if prev and prev.type != token.COMMA:
+            return NO
+
+    elif p.type == syms.typedargslist:
+        # typed function signatures
+        if not prev:
+            return NO
+
+        if t == token.EQUAL:
+            if prev.type != syms.tname:
+                return NO
+
+        elif prev.type == token.EQUAL:
+            # A bit hacky: if the equal sign has whitespace, it means we
+            # previously found it's a typed argument.  So, we're using that, too.
+            return prev.prefix
+
+        elif prev.type != token.COMMA:
+            return NO
+
+    elif p.type == syms.tname:
+        # type names
+        if not prev:
+            prevp = preceding_leaf(p)
+            if not prevp or prevp.type != token.COMMA:
+                return NO
+
+    elif p.type == syms.trailer:
+        # attributes and calls
+        if t == token.LPAR or t == token.RPAR:
+            return NO
+
+        if not prev:
+            if t == token.DOT:
+                prevp = preceding_leaf(p)
+                if not prevp or prevp.type != token.NUMBER:
+                    return NO
+
+            elif t == token.LSQB:
+                return NO
+
+        elif prev.type != token.COMMA:
+            return NO
+
+    elif p.type == syms.argument:
+        # single argument
+        if t == token.EQUAL:
+            return NO
+
+        if not prev:
+            prevp = preceding_leaf(p)
+            if not prevp or prevp.type == token.LPAR:
+                return NO
+
+        elif prev.type in {token.EQUAL} | VARARGS_SPECIALS:
+            return NO
+
+    elif p.type == syms.decorator:
+        # decorators
+        return NO
+
+    elif p.type == syms.dotted_name:
+        if prev:
+            return NO
+
+        prevp = preceding_leaf(p)
+        if not prevp or prevp.type == token.AT or prevp.type == token.DOT:
+            return NO
+
+    elif p.type == syms.classdef:
+        if t == token.LPAR:
+            return NO
+
+        if prev and prev.type == token.LPAR:
+            return NO
+
+    elif p.type in {syms.subscript, syms.sliceop}:
+        # indexing
+        if not prev:
+            assert p.parent is not None, "subscripts are always parented"
+            if p.parent.type == syms.subscriptlist:
+                return SPACE
+
+            return NO
+
+        elif not complex_subscript:
+            return NO
+
+    elif p.type == syms.atom:
+        if prev and t == token.DOT:
+            # dots, but not the first one.
+            return NO
+
+    elif p.type == syms.dictsetmaker:
+        # dict unpacking
+        if prev and prev.type == token.DOUBLESTAR:
+            return NO
+
+    elif p.type in {syms.factor, syms.star_expr}:
+        # unary ops
+        if not prev:
+            prevp = preceding_leaf(p)
+            if not prevp or prevp.type in OPENING_BRACKETS:
+                return NO
+
+            prevp_parent = prevp.parent
+            assert prevp_parent is not None
+            if prevp.type == token.COLON and prevp_parent.type in {
+                syms.subscript,
+                syms.sliceop,
+            }:
+                return NO
+
+            elif prevp.type == token.EQUAL and prevp_parent.type == syms.argument:
+                return NO
+
+        elif t in {token.NAME, token.NUMBER, token.STRING}:
+            return NO
+
+    elif p.type == syms.import_from:
+        if t == token.DOT:
+            if prev and prev.type == token.DOT:
+                return NO
+
+        elif t == token.NAME:
+            if v == "import":
+                return SPACE
+
+            if prev and prev.type == token.DOT:
+                return NO
+
+    elif p.type == syms.sliceop:
+        return NO
+
+    return SPACE
+
+
+def preceding_leaf(node: Optional[LN]) -> Optional[Leaf]:
+    """Return the first leaf that precedes `node`, if any."""
+    while node:
+        res = node.prev_sibling
+        if res:
+            if isinstance(res, Leaf):
+                return res
+
+            try:
+                return list(res.leaves())[-1]
+
+            except IndexError:
+                return None
+
+        node = node.parent
+    return None
+
+
+def child_towards(ancestor: Node, descendant: LN) -> Optional[LN]:
+    """Return the child of `ancestor` that contains `descendant`."""
+    node: Optional[LN] = descendant
+    while node and node.parent != ancestor:
+        node = node.parent
+    return node
+
+
+def container_of(leaf: Leaf) -> LN:
+    """Return `leaf` or one of its ancestors that is the topmost container of it.
+
+    By "container" we mean a node where `leaf` is the very first child.
+    """
+    same_prefix = leaf.prefix
+    container: LN = leaf
+    while container:
+        parent = container.parent
+        if parent is None:
+            break
+
+        if parent.children[0].prefix != same_prefix:
+            break
+
+        if parent.type == syms.file_input:
+            break
+
+        if parent.prev_sibling is not None and parent.prev_sibling.type in BRACKETS:
+            break
+
+        container = parent
+    return container
+
+
+def is_split_after_delimiter(leaf: Leaf, previous: Optional[Leaf] = None) -> Priority:
+    """Return the priority of the `leaf` delimiter, given a line break after it.
+
+    The delimiter priorities returned here are from those delimiters that would
+    cause a line break after themselves.
+
+    Higher numbers are higher priority.
+    """
+    if leaf.type == token.COMMA:
+        return COMMA_PRIORITY
+
+    return 0
+
+
+def is_split_before_delimiter(leaf: Leaf, previous: Optional[Leaf] = None) -> Priority:
+    """Return the priority of the `leaf` delimiter, given a line break before it.
+
+    The delimiter priorities returned here are from those delimiters that would
+    cause a line break before themselves.
+
+    Higher numbers are higher priority.
+    """
+    if is_vararg(leaf, within=VARARGS_PARENTS | UNPACKING_PARENTS):
+        # * and ** might also be MATH_OPERATORS but in this case they are not.
+        # Don't treat them as a delimiter.
+        return 0
+
+    if (
+        leaf.type == token.DOT
+        and leaf.parent
+        and leaf.parent.type not in {syms.import_from, syms.dotted_name}
+        and (previous is None or previous.type in CLOSING_BRACKETS)
+    ):
+        return DOT_PRIORITY
+
+    if (
+        leaf.type in MATH_OPERATORS
+        and leaf.parent
+        and leaf.parent.type not in {syms.factor, syms.star_expr}
+    ):
+        return MATH_PRIORITIES[leaf.type]
+
+    if leaf.type in COMPARATORS:
+        return COMPARATOR_PRIORITY
+
+    if (
+        leaf.type == token.STRING
+        and previous is not None
+        and previous.type == token.STRING
+    ):
+        return STRING_PRIORITY
+
+    if leaf.type not in {token.NAME, token.ASYNC}:
+        return 0
+
+    if (
+        leaf.value == "for"
+        and leaf.parent
+        and leaf.parent.type in {syms.comp_for, syms.old_comp_for}
+        or leaf.type == token.ASYNC
+    ):
+        if (
+            not isinstance(leaf.prev_sibling, Leaf)
+            or leaf.prev_sibling.value != "async"
+        ):
+            return COMPREHENSION_PRIORITY
+
+    if (
+        leaf.value == "if"
+        and leaf.parent
+        and leaf.parent.type in {syms.comp_if, syms.old_comp_if}
+    ):
+        return COMPREHENSION_PRIORITY
+
+    if leaf.value in {"if", "else"} and leaf.parent and leaf.parent.type == syms.test:
+        return TERNARY_PRIORITY
+
+    if leaf.value == "is":
+        return COMPARATOR_PRIORITY
+
+    if (
+        leaf.value == "in"
+        and leaf.parent
+        and leaf.parent.type in {syms.comp_op, syms.comparison}
+        and not (
+            previous is not None
+            and previous.type == token.NAME
+            and previous.value == "not"
+        )
+    ):
+        return COMPARATOR_PRIORITY
+
+    if (
+        leaf.value == "not"
+        and leaf.parent
+        and leaf.parent.type == syms.comp_op
+        and not (
+            previous is not None
+            and previous.type == token.NAME
+            and previous.value == "is"
+        )
+    ):
+        return COMPARATOR_PRIORITY
+
+    if leaf.value in LOGIC_OPERATORS and leaf.parent:
+        return LOGIC_PRIORITY
+
+    return 0
+
+
+FMT_OFF = {"# fmt: off", "# fmt:off", "# yapf: disable"}
+FMT_ON = {"# fmt: on", "# fmt:on", "# yapf: enable"}
+
+
+def generate_comments(leaf: LN) -> Iterator[Leaf]:
+    """Clean the prefix of the `leaf` and generate comments from it, if any.
+
+    Comments in lib2to3 are shoved into the whitespace prefix.  This happens
+    in `pgen2/driver.py:Driver.parse_tokens()`.  This was a brilliant implementation
+    move because it does away with modifying the grammar to include all the
+    possible places in which comments can be placed.
+
+    The sad consequence for us though is that comments don't "belong" anywhere.
+    This is why this function generates simple parentless Leaf objects for
+    comments.  We simply don't know what the correct parent should be.
+
+    No matter though, we can live without this.  We really only need to
+    differentiate between inline and standalone comments.  The latter don't
+    share the line with any code.
+
+    Inline comments are emitted as regular token.COMMENT leaves.  Standalone
+    are emitted with a fake STANDALONE_COMMENT token identifier.
+    """
+    for pc in list_comments(leaf.prefix, is_endmarker=leaf.type == token.ENDMARKER):
+        yield Leaf(pc.type, pc.value, prefix="\n" * pc.newlines)
+
+
+@dataclass
+class ProtoComment:
+    """Describes a piece of syntax that is a comment.
+
+    It's not a :class:`blib2to3.pytree.Leaf` so that:
+
+    * it can be cached (`Leaf` objects should not be reused more than once as
+      they store their lineno, column, prefix, and parent information);
+    * `newlines` and `consumed` fields are kept separate from the `value`. This
+      simplifies handling of special marker comments like ``# fmt: off/on``.
+    """
+
+    type: int  # token.COMMENT or STANDALONE_COMMENT
+    value: str  # content of the comment
+    newlines: int  # how many newlines before the comment
+    consumed: int  # how many characters of the original leaf's prefix did we consume
+
+
+@lru_cache(maxsize=4096)
+def list_comments(prefix: str, *, is_endmarker: bool) -> List[ProtoComment]:
+    """Return a list of :class:`ProtoComment` objects parsed from the given `prefix`."""
+    result: List[ProtoComment] = []
+    if not prefix or "#" not in prefix:
+        return result
+
+    consumed = 0
+    nlines = 0
+    ignored_lines = 0
+    for index, line in enumerate(prefix.split("\n")):
+        consumed += len(line) + 1  # adding the length of the split '\n'
+        line = line.lstrip()
+        if not line:
+            nlines += 1
+        if not line.startswith("#"):
+            # Escaped newlines outside of a comment are not really newlines at
+            # all. We treat a single-line comment following an escaped newline
+            # as a simple trailing comment.
+            if line.endswith("\\"):
+                ignored_lines += 1
+            continue
+
+        if index == ignored_lines and not is_endmarker:
+            comment_type = token.COMMENT  # simple trailing comment
+        else:
+            comment_type = STANDALONE_COMMENT
+        comment = make_comment(line)
+        result.append(
+            ProtoComment(
+                type=comment_type, value=comment, newlines=nlines, consumed=consumed
+            )
+        )
+        nlines = 0
+    return result
+
+
+def make_comment(content: str) -> str:
+    """Return a consistently formatted comment from the given `content` string.
+
+    All comments (except for "##", "#!", "#:", '#'", "#%%") should have a single
+    space between the hash sign and the content.
+
+    If `content` didn't start with a hash sign, one is provided.
+    """
+    content = content.rstrip()
+    if not content:
+        return "#"
+
+    if content[0] == "#":
+        content = content[1:]
+    if content and content[0] not in " !:#'%":
+        content = " " + content
+    return "#" + content
+
+
+def split_line(
+    line: Line,
+    line_length: int,
+    inner: bool = False,
+    features: Collection[Feature] = (),
+) -> Iterator[Line]:
+    """Split a `line` into potentially many lines.
+
+    They should fit in the allotted `line_length` but might not be able to.
+    `inner` signifies that there were a pair of brackets somewhere around the
+    current `line`, possibly transitively. This means we can fallback to splitting
+    by delimiters if the LHS/RHS don't yield any results.
+
+    `features` are syntactical features that may be used in the output.
+    """
+    if line.is_comment:
+        yield line
+        return
+
+    line_str = str(line).strip("\n")
+
+    if (
+        not line.contains_uncollapsable_type_comments()
+        and not line.should_explode
+        and not line.is_collection_with_optional_trailing_comma
+        and (
+            is_line_short_enough(line, line_length=line_length, line_str=line_str)
+            or line.contains_unsplittable_type_ignore()
+        )
+    ):
+        yield line
+        return
+
+    split_funcs: List[SplitFunc]
+    if line.is_def:
+        split_funcs = [left_hand_split]
+    else:
+
+        def rhs(line: Line, features: Collection[Feature]) -> Iterator[Line]:
+            for omit in generate_trailers_to_omit(line, line_length):
+                lines = list(right_hand_split(line, line_length, features, omit=omit))
+                if is_line_short_enough(lines[0], line_length=line_length):
+                    yield from lines
+                    return
+
+            # All splits failed, best effort split with no omits.
+            # This mostly happens to multiline strings that are by definition
+            # reported as not fitting a single line.
+            yield from right_hand_split(line, line_length, features=features)
+
+        if line.inside_brackets:
+            split_funcs = [delimiter_split, standalone_comment_split, rhs]
+        else:
+            split_funcs = [rhs]
+    for split_func in split_funcs:
+        # We are accumulating lines in `result` because we might want to abort
+        # mission and return the original line in the end, or attempt a different
+        # split altogether.
+        result: List[Line] = []
+        try:
+            for l in split_func(line, features):
+                if str(l).strip("\n") == line_str:
+                    raise CannotSplit("Split function returned an unchanged result")
+
+                result.extend(
+                    split_line(
+                        l, line_length=line_length, inner=True, features=features
+                    )
+                )
+        except CannotSplit:
+            continue
+
+        else:
+            yield from result
+            break
+
+    else:
+        yield line
+
+
+def left_hand_split(line: Line, features: Collection[Feature] = ()) -> Iterator[Line]:
+    """Split line into many lines, starting with the first matching bracket pair.
+
+    Note: this usually looks weird, only use this for function definitions.
+    Prefer RHS otherwise.  This is why this function is not symmetrical with
+    :func:`right_hand_split` which also handles optional parentheses.
+    """
+    tail_leaves: List[Leaf] = []
+    body_leaves: List[Leaf] = []
+    head_leaves: List[Leaf] = []
+    current_leaves = head_leaves
+    matching_bracket = None
+    for leaf in line.leaves:
+        if (
+            current_leaves is body_leaves
+            and leaf.type in CLOSING_BRACKETS
+            and leaf.opening_bracket is matching_bracket
+        ):
+            current_leaves = tail_leaves if body_leaves else head_leaves
+        current_leaves.append(leaf)
+        if current_leaves is head_leaves:
+            if leaf.type in OPENING_BRACKETS:
+                matching_bracket = leaf
+                current_leaves = body_leaves
+    if not matching_bracket:
+        raise CannotSplit("No brackets found")
+
+    head = bracket_split_build_line(head_leaves, line, matching_bracket)
+    body = bracket_split_build_line(body_leaves, line, matching_bracket, is_body=True)
+    tail = bracket_split_build_line(tail_leaves, line, matching_bracket)
+    bracket_split_succeeded_or_raise(head, body, tail)
+    for result in (head, body, tail):
+        if result:
+            yield result
+
+
+def right_hand_split(
+    line: Line,
+    line_length: int,
+    features: Collection[Feature] = (),
+    omit: Collection[LeafID] = (),
+) -> Iterator[Line]:
+    """Split line into many lines, starting with the last matching bracket pair.
+
+    If the split was by optional parentheses, attempt splitting without them, too.
+    `omit` is a collection of closing bracket IDs that shouldn't be considered for
+    this split.
+
+    Note: running this function modifies `bracket_depth` on the leaves of `line`.
+    """
+    tail_leaves: List[Leaf] = []
+    body_leaves: List[Leaf] = []
+    head_leaves: List[Leaf] = []
+    current_leaves = tail_leaves
+    opening_bracket = None
+    closing_bracket = None
+    for leaf in reversed(line.leaves):
+        if current_leaves is body_leaves:
+            if leaf is opening_bracket:
+                current_leaves = head_leaves if body_leaves else tail_leaves
+        current_leaves.append(leaf)
+        if current_leaves is tail_leaves:
+            if leaf.type in CLOSING_BRACKETS and id(leaf) not in omit:
+                opening_bracket = leaf.opening_bracket
+                closing_bracket = leaf
+                current_leaves = body_leaves
+    if not (opening_bracket and closing_bracket and head_leaves):
+        # If there is no opening or closing_bracket that means the split failed and
+        # all content is in the tail.  Otherwise, if `head_leaves` are empty, it means
+        # the matching `opening_bracket` wasn't available on `line` anymore.
+        raise CannotSplit("No brackets found")
+
+    tail_leaves.reverse()
+    body_leaves.reverse()
+    head_leaves.reverse()
+    head = bracket_split_build_line(head_leaves, line, opening_bracket)
+    body = bracket_split_build_line(body_leaves, line, opening_bracket, is_body=True)
+    tail = bracket_split_build_line(tail_leaves, line, opening_bracket)
+    bracket_split_succeeded_or_raise(head, body, tail)
+    if (
+        # the body shouldn't be exploded
+        not body.should_explode
+        # the opening bracket is an optional paren
+        and opening_bracket.type == token.LPAR
+        and not opening_bracket.value
+        # the closing bracket is an optional paren
+        and closing_bracket.type == token.RPAR
+        and not closing_bracket.value
+        # it's not an import (optional parens are the only thing we can split on
+        # in this case; attempting a split without them is a waste of time)
+        and not line.is_import
+        # there are no standalone comments in the body
+        and not body.contains_standalone_comments(0)
+        # and we can actually remove the parens
+        and can_omit_invisible_parens(body, line_length)
+    ):
+        omit = {id(closing_bracket), *omit}
+        try:
+            yield from right_hand_split(line, line_length, features=features, omit=omit)
+            return
+
+        except CannotSplit:
+            if not (
+                can_be_split(body)
+                or is_line_short_enough(body, line_length=line_length)
+            ):
+                raise CannotSplit(
+                    "Splitting failed, body is still too long and can't be split."
+                )
+
+            elif head.contains_multiline_strings() or tail.contains_multiline_strings():
+                raise CannotSplit(
+                    "The current optional pair of parentheses is bound to fail to "
+                    "satisfy the splitting algorithm because the head or the tail "
+                    "contains multiline strings which by definition never fit one "
+                    "line."
+                )
+
+    ensure_visible(opening_bracket)
+    ensure_visible(closing_bracket)
+    for result in (head, body, tail):
+        if result:
+            yield result
+
+
+def bracket_split_succeeded_or_raise(head: Line, body: Line, tail: Line) -> None:
+    """Raise :exc:`CannotSplit` if the last left- or right-hand split failed.
+
+    Do nothing otherwise.
+
+    A left- or right-hand split is based on a pair of brackets. Content before
+    (and including) the opening bracket is left on one line, content inside the
+    brackets is put on a separate line, and finally content starting with and
+    following the closing bracket is put on a separate line.
+
+    Those are called `head`, `body`, and `tail`, respectively. If the split
+    produced the same line (all content in `head`) or ended up with an empty `body`
+    and the `tail` is just the closing bracket, then it's considered failed.
+    """
+    tail_len = len(str(tail).strip())
+    if not body:
+        if tail_len == 0:
+            raise CannotSplit("Splitting brackets produced the same line")
+
+        elif tail_len < 3:
+            raise CannotSplit(
+                f"Splitting brackets on an empty body to save "
+                f"{tail_len} characters is not worth it"
+            )
+
+
+def bracket_split_build_line(
+    leaves: List[Leaf], original: Line, opening_bracket: Leaf, *, is_body: bool = False
+) -> Line:
+    """Return a new line with given `leaves` and respective comments from `original`.
+
+    If `is_body` is True, the result line is one-indented inside brackets and as such
+    has its first leaf's prefix normalized and a trailing comma added when expected.
+    """
+    result = Line(depth=original.depth)
+    if is_body:
+        result.inside_brackets = True
+        result.depth += 1
+        if leaves:
+            # Since body is a new indent level, remove spurious leading whitespace.
+            normalize_prefix(leaves[0], inside_brackets=True)
+            # Ensure a trailing comma for imports and standalone function arguments, but
+            # be careful not to add one after any comments.
+            no_commas = original.is_def and not any(
+                l.type == token.COMMA for l in leaves
+            )
+
+            if original.is_import or no_commas:
+                for i in range(len(leaves) - 1, -1, -1):
+                    if leaves[i].type == STANDALONE_COMMENT:
+                        continue
+                    elif leaves[i].type == token.COMMA:
+                        break
+                    else:
+                        leaves.insert(i + 1, Leaf(token.COMMA, ","))
+                        break
+    # Populate the line
+    for leaf in leaves:
+        result.append(leaf, preformatted=True)
+        for comment_after in original.comments_after(leaf):
+            result.append(comment_after, preformatted=True)
+    if is_body:
+        result.should_explode = should_explode(result, opening_bracket)
+    return result
+
+
+def dont_increase_indentation(split_func: SplitFunc) -> SplitFunc:
+    """Normalize prefix of the first leaf in every line returned by `split_func`.
+
+    This is a decorator over relevant split functions.
+    """
+
+    @wraps(split_func)
+    def split_wrapper(line: Line, features: Collection[Feature] = ()) -> Iterator[Line]:
+        for l in split_func(line, features):
+            normalize_prefix(l.leaves[0], inside_brackets=True)
+            yield l
+
+    return split_wrapper
+
+
+@dont_increase_indentation
+def delimiter_split(line: Line, features: Collection[Feature] = ()) -> Iterator[Line]:
+    """Split according to delimiters of the highest priority.
+
+    If the appropriate Features are given, the split will add trailing commas
+    also in function signatures and calls that contain `*` and `**`.
+    """
+    try:
+        last_leaf = line.leaves[-1]
+    except IndexError:
+        raise CannotSplit("Line empty")
+
+    bt = line.bracket_tracker
+    try:
+        delimiter_priority = bt.max_delimiter_priority(exclude={id(last_leaf)})
+    except ValueError:
+        raise CannotSplit("No delimiters found")
+
+    if delimiter_priority == DOT_PRIORITY:
+        if bt.delimiter_count_with_priority(delimiter_priority) == 1:
+            raise CannotSplit("Splitting a single attribute from its owner looks wrong")
+
+    current_line = Line(depth=line.depth, inside_brackets=line.inside_brackets)
+    lowest_depth = sys.maxsize
+    trailing_comma_safe = True
+
+    def append_to_line(leaf: Leaf) -> Iterator[Line]:
+        """Append `leaf` to current line or to new line if appending impossible."""
+        nonlocal current_line
+        try:
+            current_line.append_safe(leaf, preformatted=True)
+        except ValueError:
+            yield current_line
+
+            current_line = Line(depth=line.depth, inside_brackets=line.inside_brackets)
+            current_line.append(leaf)
+
+    for leaf in line.leaves:
+        yield from append_to_line(leaf)
+
+        for comment_after in line.comments_after(leaf):
+            yield from append_to_line(comment_after)
+
+        lowest_depth = min(lowest_depth, leaf.bracket_depth)
+        if leaf.bracket_depth == lowest_depth:
+            if is_vararg(leaf, within={syms.typedargslist}):
+                trailing_comma_safe = (
+                    trailing_comma_safe and Feature.TRAILING_COMMA_IN_DEF in features
+                )
+            elif is_vararg(leaf, within={syms.arglist, syms.argument}):
+                trailing_comma_safe = (
+                    trailing_comma_safe and Feature.TRAILING_COMMA_IN_CALL in features
+                )
+
+        leaf_priority = bt.delimiters.get(id(leaf))
+        if leaf_priority == delimiter_priority:
+            yield current_line
+
+            current_line = Line(depth=line.depth, inside_brackets=line.inside_brackets)
+    if current_line:
+        if (
+            trailing_comma_safe
+            and delimiter_priority == COMMA_PRIORITY
+            and current_line.leaves[-1].type != token.COMMA
+            and current_line.leaves[-1].type != STANDALONE_COMMENT
+        ):
+            current_line.append(Leaf(token.COMMA, ","))
+        yield current_line
+
+
+@dont_increase_indentation
+def standalone_comment_split(
+    line: Line, features: Collection[Feature] = ()
+) -> Iterator[Line]:
+    """Split standalone comments from the rest of the line."""
+    if not line.contains_standalone_comments(0):
+        raise CannotSplit("Line does not have any standalone comments")
+
+    current_line = Line(depth=line.depth, inside_brackets=line.inside_brackets)
+
+    def append_to_line(leaf: Leaf) -> Iterator[Line]:
+        """Append `leaf` to current line or to new line if appending impossible."""
+        nonlocal current_line
+        try:
+            current_line.append_safe(leaf, preformatted=True)
+        except ValueError:
+            yield current_line
+
+            current_line = Line(depth=line.depth, inside_brackets=line.inside_brackets)
+            current_line.append(leaf)
+
+    for leaf in line.leaves:
+        yield from append_to_line(leaf)
+
+        for comment_after in line.comments_after(leaf):
+            yield from append_to_line(comment_after)
+
+    if current_line:
+        yield current_line
+
+
+def is_import(leaf: Leaf) -> bool:
+    """Return True if the given leaf starts an import statement."""
+    p = leaf.parent
+    t = leaf.type
+    v = leaf.value
+    return bool(
+        t == token.NAME
+        and (
+            (v == "import" and p and p.type == syms.import_name)
+            or (v == "from" and p and p.type == syms.import_from)
+        )
+    )
+
+
+def is_type_comment(leaf: Leaf, suffix: str = "") -> bool:
+    """Return True if the given leaf is a special comment.
+    Only returns true for type comments for now."""
+    t = leaf.type
+    v = leaf.value
+    return t in {token.COMMENT, t == STANDALONE_COMMENT} and v.startswith(
+        "# type:" + suffix
+    )
+
+
+def normalize_prefix(leaf: Leaf, *, inside_brackets: bool) -> None:
+    """Leave existing extra newlines if not `inside_brackets`. Remove everything
+    else.
+
+    Note: don't use backslashes for formatting or you'll lose your voting rights.
+    """
+    if not inside_brackets:
+        spl = leaf.prefix.split("#")
+        if "\\" not in spl[0]:
+            nl_count = spl[-1].count("\n")
+            if len(spl) > 1:
+                nl_count -= 1
+            leaf.prefix = "\n" * nl_count
+            return
+
+    leaf.prefix = ""
+
+
+def normalize_string_prefix(leaf: Leaf, remove_u_prefix: bool = False) -> None:
+    """Make all string prefixes lowercase.
+
+    If remove_u_prefix is given, also removes any u prefix from the string.
+
+    Note: Mutates its argument.
+    """
+    match = re.match(r"^([furbFURB]*)(.*)$", leaf.value, re.DOTALL)
+    assert match is not None, f"failed to match string {leaf.value!r}"
+    orig_prefix = match.group(1)
+    new_prefix = orig_prefix.lower()
+    if remove_u_prefix:
+        new_prefix = new_prefix.replace("u", "")
+    leaf.value = f"{new_prefix}{match.group(2)}"
+
+
+def normalize_string_quotes(leaf: Leaf) -> None:
+    """Prefer double quotes but only if it doesn't cause more escaping.
+
+    Adds or removes backslashes as appropriate. Doesn't parse and fix
+    strings nested in f-strings (yet).
+
+    Note: Mutates its argument.
+    """
+    value = leaf.value.lstrip("furbFURB")
+    if value[:3] == '"""':
+        return
+
+    elif value[:3] == "'''":
+        orig_quote = "'''"
+        new_quote = '"""'
+    elif value[0] == '"':
+        orig_quote = '"'
+        new_quote = "'"
+    else:
+        orig_quote = "'"
+        new_quote = '"'
+    first_quote_pos = leaf.value.find(orig_quote)
+    if first_quote_pos == -1:
+        return  # There's an internal error
+
+    prefix = leaf.value[:first_quote_pos]
+    unescaped_new_quote = re.compile(rf"(([^\\]|^)(\\\\)*){new_quote}")
+    escaped_new_quote = re.compile(rf"([^\\]|^)\\((?:\\\\)*){new_quote}")
+    escaped_orig_quote = re.compile(rf"([^\\]|^)\\((?:\\\\)*){orig_quote}")
+    body = leaf.value[first_quote_pos + len(orig_quote) : -len(orig_quote)]
+    if "r" in prefix.casefold():
+        if unescaped_new_quote.search(body):
+            # There's at least one unescaped new_quote in this raw string
+            # so converting is impossible
+            return
+
+        # Do not introduce or remove backslashes in raw strings
+        new_body = body
+    else:
+        # remove unnecessary escapes
+        new_body = sub_twice(escaped_new_quote, rf"\1\2{new_quote}", body)
+        if body != new_body:
+            # Consider the string without unnecessary escapes as the original
+            body = new_body
+            leaf.value = f"{prefix}{orig_quote}{body}{orig_quote}"
+        new_body = sub_twice(escaped_orig_quote, rf"\1\2{orig_quote}", new_body)
+        new_body = sub_twice(unescaped_new_quote, rf"\1\\{new_quote}", new_body)
+    if "f" in prefix.casefold():
+        matches = re.findall(
+            r"""
+            (?:[^{]|^)\{  # start of the string or a non-{ followed by a single {
+                ([^{].*?)  # contents of the brackets except if begins with {{
+            \}(?:[^}]|$)  # A } followed by end of the string or a non-}
+            """,
+            new_body,
+            re.VERBOSE,
+        )
+        for m in matches:
+            if "\\" in str(m):
+                # Do not introduce backslashes in interpolated expressions
+                return
+    if new_quote == '"""' and new_body[-1:] == '"':
+        # edge case:
+        new_body = new_body[:-1] + '\\"'
+    orig_escape_count = body.count("\\")
+    new_escape_count = new_body.count("\\")
+    if new_escape_count > orig_escape_count:
+        return  # Do not introduce more escaping
+
+    if new_escape_count == orig_escape_count and orig_quote == '"':
+        return  # Prefer double quotes
+
+    leaf.value = f"{prefix}{new_quote}{new_body}{new_quote}"
+
+
+def normalize_numeric_literal(leaf: Leaf) -> None:
+    """Normalizes numeric (float, int, and complex) literals.
+
+    All letters used in the representation are normalized to lowercase (except
+    in Python 2 long literals).
+    """
+    text = leaf.value.lower()
+    if text.startswith(("0o", "0b")):
+        # Leave octal and binary literals alone.
+        pass
+    elif text.startswith("0x"):
+        # Change hex literals to upper case.
+        before, after = text[:2], text[2:]
+        text = f"{before}{after.upper()}"
+    elif "e" in text:
+        before, after = text.split("e")
+        sign = ""
+        if after.startswith("-"):
+            after = after[1:]
+            sign = "-"
+        elif after.startswith("+"):
+            after = after[1:]
+        before = format_float_or_int_string(before)
+        text = f"{before}e{sign}{after}"
+    elif text.endswith(("j", "l")):
+        number = text[:-1]
+        suffix = text[-1]
+        # Capitalize in "2L" because "l" looks too similar to "1".
+        if suffix == "l":
+            suffix = "L"
+        text = f"{format_float_or_int_string(number)}{suffix}"
+    else:
+        text = format_float_or_int_string(text)
+    leaf.value = text
+
+
+def format_float_or_int_string(text: str) -> str:
+    """Formats a float string like "1.0"."""
+    if "." not in text:
+        return text
+
+    before, after = text.split(".")
+    return f"{before or 0}.{after or 0}"
+
+
+def normalize_invisible_parens(node: Node, parens_after: Set[str]) -> None:
+    """Make existing optional parentheses invisible or create new ones.
+
+    `parens_after` is a set of string leaf values immediately after which parens
+    should be put.
+
+    Standardizes on visible parentheses for single-element tuples, and keeps
+    existing visible parentheses for other tuples and generator expressions.
+    """
+    for pc in list_comments(node.prefix, is_endmarker=False):
+        if pc.value in FMT_OFF:
+            # This `node` has a prefix with `# fmt: off`, don't mess with parens.
+            return
+
+    check_lpar = False
+    for index, child in enumerate(list(node.children)):
+        # Add parentheses around long tuple unpacking in assignments.
+        if (
+            index == 0
+            and isinstance(child, Node)
+            and child.type == syms.testlist_star_expr
+        ):
+            check_lpar = True
+
+        if check_lpar:
+            if is_walrus_assignment(child):
+                continue
+            if child.type == syms.atom:
+                # Determines if the underlying atom should be surrounded with
+                # invisible params - also makes parens invisible recursively
+                # within the atom and removes repeated invisible parens within
+                # the atom
+                should_surround_with_parens = maybe_make_parens_invisible_in_atom(
+                    child, parent=node
+                )
+
+                if should_surround_with_parens:
+                    lpar = Leaf(token.LPAR, "")
+                    rpar = Leaf(token.RPAR, "")
+                    index = child.remove() or 0
+                    node.insert_child(index, Node(syms.atom, [lpar, child, rpar]))
+            elif is_one_tuple(child):
+                # wrap child in visible parentheses
+                lpar = Leaf(token.LPAR, "(")
+                rpar = Leaf(token.RPAR, ")")
+                child.remove()
+                node.insert_child(index, Node(syms.atom, [lpar, child, rpar]))
+            elif node.type == syms.import_from:
+                # "import from" nodes store parentheses directly as part of
+                # the statement
+                if child.type == token.LPAR:
+                    # make parentheses invisible
+                    child.value = ""  # type: ignore
+                    node.children[-1].value = ""  # type: ignore
+                elif child.type != token.STAR:
+                    # insert invisible parentheses
+                    node.insert_child(index, Leaf(token.LPAR, ""))
+                    node.append_child(Leaf(token.RPAR, ""))
+                break
+
+            elif not (isinstance(child, Leaf) and is_multiline_string(child)):
+                # wrap child in invisible parentheses
+                lpar = Leaf(token.LPAR, "")
+                rpar = Leaf(token.RPAR, "")
+                index = child.remove() or 0
+                prefix = child.prefix
+                child.prefix = ""
+                new_child = Node(syms.atom, [lpar, child, rpar])
+                new_child.prefix = prefix
+                node.insert_child(index, new_child)
+
+        check_lpar = isinstance(child, Leaf) and child.value in parens_after
+
+
+def normalize_fmt_off(node: Node) -> None:
+    """Convert content between `# fmt: off`/`# fmt: on` into standalone comments."""
+    try_again = True
+    while try_again:
+        try_again = convert_one_fmt_off_pair(node)
+
+
+def convert_one_fmt_off_pair(node: Node) -> bool:
+    """Convert content of a single `# fmt: off`/`# fmt: on` into a standalone comment.
+
+    Returns True if a pair was converted.
+    """
+    for leaf in node.leaves():
+        previous_consumed = 0
+        for comment in list_comments(leaf.prefix, is_endmarker=False):
+            if comment.value in FMT_OFF:
+                # We only want standalone comments. If there's no previous leaf or
+                # the previous leaf is indentation, it's a standalone comment in
+                # disguise.
+                if comment.type != STANDALONE_COMMENT:
+                    prev = preceding_leaf(leaf)
+                    if prev and prev.type not in WHITESPACE:
+                        continue
+
+                ignored_nodes = list(generate_ignored_nodes(leaf))
+                if not ignored_nodes:
+                    continue
+
+                first = ignored_nodes[0]  # Can be a container node with the `leaf`.
+                parent = first.parent
+                prefix = first.prefix
+                first.prefix = prefix[comment.consumed :]
+                hidden_value = (
+                    comment.value + "\n" + "".join(str(n) for n in ignored_nodes)
+                )
+                if hidden_value.endswith("\n"):
+                    # That happens when one of the `ignored_nodes` ended with a NEWLINE
+                    # leaf (possibly followed by a DEDENT).
+                    hidden_value = hidden_value[:-1]
+                first_idx = None
+                for ignored in ignored_nodes:
+                    index = ignored.remove()
+                    if first_idx is None:
+                        first_idx = index
+                assert parent is not None, "INTERNAL ERROR: fmt: on/off handling (1)"
+                assert first_idx is not None, "INTERNAL ERROR: fmt: on/off handling (2)"
+                parent.insert_child(
+                    first_idx,
+                    Leaf(
+                        STANDALONE_COMMENT,
+                        hidden_value,
+                        prefix=prefix[:previous_consumed] + "\n" * comment.newlines,
+                    ),
+                )
+                return True
+
+            previous_consumed = comment.consumed
+
+    return False
+
+
+def generate_ignored_nodes(leaf: Leaf) -> Iterator[LN]:
+    """Starting from the container of `leaf`, generate all leaves until `# fmt: on`.
+
+    Stops at the end of the block.
+    """
+    container: Optional[LN] = container_of(leaf)
+    while container is not None and container.type != token.ENDMARKER:
+        for comment in list_comments(container.prefix, is_endmarker=False):
+            if comment.value in FMT_ON:
+                return
+
+        yield container
+
+        container = container.next_sibling
+
+
+def maybe_make_parens_invisible_in_atom(node: LN, parent: LN) -> bool:
+    """If it's safe, make the parens in the atom `node` invisible, recursively.
+    Additionally, remove repeated, adjacent invisible parens from the atom `node`
+    as they are redundant.
+
+    Returns whether the node should itself be wrapped in invisible parentheses.
+
+    """
+    if (
+        node.type != syms.atom
+        or is_empty_tuple(node)
+        or is_one_tuple(node)
+        or (is_yield(node) and parent.type != syms.expr_stmt)
+        or max_delimiter_priority_in_atom(node) >= COMMA_PRIORITY
+    ):
+        return False
+
+    first = node.children[0]
+    last = node.children[-1]
+    if first.type == token.LPAR and last.type == token.RPAR:
+        middle = node.children[1]
+        # make parentheses invisible
+        first.value = ""  # type: ignore
+        last.value = ""  # type: ignore
+        maybe_make_parens_invisible_in_atom(middle, parent=parent)
+
+        if is_atom_with_invisible_parens(middle):
+            # Strip the invisible parens from `middle` by replacing
+            # it with the child in-between the invisible parens
+            middle.replace(middle.children[1])
+
+        return False
+
+    return True
+
+
+def is_atom_with_invisible_parens(node: LN) -> bool:
+    """Given a `LN`, determines whether it's an atom `node` with invisible
+    parens. Useful in dedupe-ing and normalizing parens.
+    """
+    if isinstance(node, Leaf) or node.type != syms.atom:
+        return False
+
+    first, last = node.children[0], node.children[-1]
+    return (
+        isinstance(first, Leaf)
+        and first.type == token.LPAR
+        and first.value == ""
+        and isinstance(last, Leaf)
+        and last.type == token.RPAR
+        and last.value == ""
+    )
+
+
+def is_empty_tuple(node: LN) -> bool:
+    """Return True if `node` holds an empty tuple."""
+    return (
+        node.type == syms.atom
+        and len(node.children) == 2
+        and node.children[0].type == token.LPAR
+        and node.children[1].type == token.RPAR
+    )
+
+
+def unwrap_singleton_parenthesis(node: LN) -> Optional[LN]:
+    """Returns `wrapped` if `node` is of the shape ( wrapped ).
+
+    Parenthesis can be optional. Returns None otherwise"""
+    if len(node.children) != 3:
+        return None
+    lpar, wrapped, rpar = node.children
+    if not (lpar.type == token.LPAR and rpar.type == token.RPAR):
+        return None
+
+    return wrapped
+
+
+def is_one_tuple(node: LN) -> bool:
+    """Return True if `node` holds a tuple with one element, with or without parens."""
+    if node.type == syms.atom:
+        gexp = unwrap_singleton_parenthesis(node)
+        if gexp is None or gexp.type != syms.testlist_gexp:
+            return False
+
+        return len(gexp.children) == 2 and gexp.children[1].type == token.COMMA
+
+    return (
+        node.type in IMPLICIT_TUPLE
+        and len(node.children) == 2
+        and node.children[1].type == token.COMMA
+    )
+
+
+def is_walrus_assignment(node: LN) -> bool:
+    """Return True iff `node` is of the shape ( test := test )"""
+    inner = unwrap_singleton_parenthesis(node)
+    return inner is not None and inner.type == syms.namedexpr_test
+
+
+def is_yield(node: LN) -> bool:
+    """Return True if `node` holds a `yield` or `yield from` expression."""
+    if node.type == syms.yield_expr:
+        return True
+
+    if node.type == token.NAME and node.value == "yield":  # type: ignore
+        return True
+
+    if node.type != syms.atom:
+        return False
+
+    if len(node.children) != 3:
+        return False
+
+    lpar, expr, rpar = node.children
+    if lpar.type == token.LPAR and rpar.type == token.RPAR:
+        return is_yield(expr)
+
+    return False
+
+
+def is_vararg(leaf: Leaf, within: Set[NodeType]) -> bool:
+    """Return True if `leaf` is a star or double star in a vararg or kwarg.
+
+    If `within` includes VARARGS_PARENTS, this applies to function signatures.
+    If `within` includes UNPACKING_PARENTS, it applies to right hand-side
+    extended iterable unpacking (PEP 3132) and additional unpacking
+    generalizations (PEP 448).
+    """
+    if leaf.type not in VARARGS_SPECIALS or not leaf.parent:
+        return False
+
+    p = leaf.parent
+    if p.type == syms.star_expr:
+        # Star expressions are also used as assignment targets in extended
+        # iterable unpacking (PEP 3132).  See what its parent is instead.
+        if not p.parent:
+            return False
+
+        p = p.parent
+
+    return p.type in within
+
+
+def is_multiline_string(leaf: Leaf) -> bool:
+    """Return True if `leaf` is a multiline string that actually spans many lines."""
+    value = leaf.value.lstrip("furbFURB")
+    return value[:3] in {'"""', "'''"} and "\n" in value
+
+
+def is_stub_suite(node: Node) -> bool:
+    """Return True if `node` is a suite with a stub body."""
+    if (
+        len(node.children) != 4
+        or node.children[0].type != token.NEWLINE
+        or node.children[1].type != token.INDENT
+        or node.children[3].type != token.DEDENT
+    ):
+        return False
+
+    return is_stub_body(node.children[2])
+
+
+def is_stub_body(node: LN) -> bool:
+    """Return True if `node` is a simple statement containing an ellipsis."""
+    if not isinstance(node, Node) or node.type != syms.simple_stmt:
+        return False
+
+    if len(node.children) != 2:
+        return False
+
+    child = node.children[0]
+    return (
+        child.type == syms.atom
+        and len(child.children) == 3
+        and all(leaf == Leaf(token.DOT, ".") for leaf in child.children)
+    )
+
+
+def max_delimiter_priority_in_atom(node: LN) -> Priority:
+    """Return maximum delimiter priority inside `node`.
+
+    This is specific to atoms with contents contained in a pair of parentheses.
+    If `node` isn't an atom or there are no enclosing parentheses, returns 0.
+    """
+    if node.type != syms.atom:
+        return 0
+
+    first = node.children[0]
+    last = node.children[-1]
+    if not (first.type == token.LPAR and last.type == token.RPAR):
+        return 0
+
+    bt = BracketTracker()
+    for c in node.children[1:-1]:
+        if isinstance(c, Leaf):
+            bt.mark(c)
+        else:
+            for leaf in c.leaves():
+                bt.mark(leaf)
+    try:
+        return bt.max_delimiter_priority()
+
+    except ValueError:
+        return 0
+
+
+def ensure_visible(leaf: Leaf) -> None:
+    """Make sure parentheses are visible.
+
+    They could be invisible as part of some statements (see
+    :func:`normalize_invisible_parens` and :func:`visit_import_from`).
+    """
+    if leaf.type == token.LPAR:
+        leaf.value = "("
+    elif leaf.type == token.RPAR:
+        leaf.value = ")"
+
+
+def should_explode(line: Line, opening_bracket: Leaf) -> bool:
+    """Should `line` immediately be split with `delimiter_split()` after RHS?"""
+
+    if not (
+        opening_bracket.parent
+        and opening_bracket.parent.type in {syms.atom, syms.import_from}
+        and opening_bracket.value in "[{("
+    ):
+        return False
+
+    try:
+        last_leaf = line.leaves[-1]
+        exclude = {id(last_leaf)} if last_leaf.type == token.COMMA else set()
+        max_priority = line.bracket_tracker.max_delimiter_priority(exclude=exclude)
+    except (IndexError, ValueError):
+        return False
+
+    return max_priority == COMMA_PRIORITY
+
+
+def get_features_used(node: Node) -> Set[Feature]:
+    """Return a set of (relatively) new Python features used in this file.
+
+    Currently looking for:
+    - f-strings;
+    - underscores in numeric literals;
+    - trailing commas after * or ** in function signatures and calls;
+    - positional only arguments in function signatures and lambdas;
+    """
+    features: Set[Feature] = set()
+    for n in node.pre_order():
+        if n.type == token.STRING:
+            value_head = n.value[:2]  # type: ignore
+            if value_head in {'f"', 'F"', "f'", "F'", "rf", "fr", "RF", "FR"}:
+                features.add(Feature.F_STRINGS)
+
+        elif n.type == token.NUMBER:
+            if "_" in n.value:  # type: ignore
+                features.add(Feature.NUMERIC_UNDERSCORES)
+
+        elif n.type == token.SLASH:
+            if n.parent and n.parent.type in {syms.typedargslist, syms.arglist}:
+                features.add(Feature.POS_ONLY_ARGUMENTS)
+
+        elif n.type == token.COLONEQUAL:
+            features.add(Feature.ASSIGNMENT_EXPRESSIONS)
+
+        elif (
+            n.type in {syms.typedargslist, syms.arglist}
+            and n.children
+            and n.children[-1].type == token.COMMA
+        ):
+            if n.type == syms.typedargslist:
+                feature = Feature.TRAILING_COMMA_IN_DEF
+            else:
+                feature = Feature.TRAILING_COMMA_IN_CALL
+
+            for ch in n.children:
+                if ch.type in STARS:
+                    features.add(feature)
+
+                if ch.type == syms.argument:
+                    for argch in ch.children:
+                        if argch.type in STARS:
+                            features.add(feature)
+
+    return features
+
+
+def detect_target_versions(node: Node) -> Set[TargetVersion]:
+    """Detect the version to target based on the nodes used."""
+    features = get_features_used(node)
+    return {
+        version for version in TargetVersion if features <= VERSION_TO_FEATURES[version]
+    }
+
+
+def generate_trailers_to_omit(line: Line, line_length: int) -> Iterator[Set[LeafID]]:
+    """Generate sets of closing bracket IDs that should be omitted in a RHS.
+
+    Brackets can be omitted if the entire trailer up to and including
+    a preceding closing bracket fits in one line.
+
+    Yielded sets are cumulative (contain results of previous yields, too).  First
+    set is empty.
+    """
+
+    omit: Set[LeafID] = set()
+    yield omit
+
+    length = 4 * line.depth
+    opening_bracket = None
+    closing_bracket = None
+    inner_brackets: Set[LeafID] = set()
+    for index, leaf, leaf_length in enumerate_with_length(line, reversed=True):
+        length += leaf_length
+        if length > line_length:
+            break
+
+        has_inline_comment = leaf_length > len(leaf.value) + len(leaf.prefix)
+        if leaf.type == STANDALONE_COMMENT or has_inline_comment:
+            break
+
+        if opening_bracket:
+            if leaf is opening_bracket:
+                opening_bracket = None
+            elif leaf.type in CLOSING_BRACKETS:
+                inner_brackets.add(id(leaf))
+        elif leaf.type in CLOSING_BRACKETS:
+            if index > 0 and line.leaves[index - 1].type in OPENING_BRACKETS:
+                # Empty brackets would fail a split so treat them as "inner"
+                # brackets (e.g. only add them to the `omit` set if another
+                # pair of brackets was good enough.
+                inner_brackets.add(id(leaf))
+                continue
+
+            if closing_bracket:
+                omit.add(id(closing_bracket))
+                omit.update(inner_brackets)
+                inner_brackets.clear()
+                yield omit
+
+            if leaf.value:
+                opening_bracket = leaf.opening_bracket
+                closing_bracket = leaf
+
+
+def get_future_imports(node: Node) -> Set[str]:
+    """Return a set of __future__ imports in the file."""
+    imports: Set[str] = set()
+
+    def get_imports_from_children(children: List[LN]) -> Generator[str, None, None]:
+        for child in children:
+            if isinstance(child, Leaf):
+                if child.type == token.NAME:
+                    yield child.value
+            elif child.type == syms.import_as_name:
+                orig_name = child.children[0]
+                assert isinstance(orig_name, Leaf), "Invalid syntax parsing imports"
+                assert orig_name.type == token.NAME, "Invalid syntax parsing imports"
+                yield orig_name.value
+            elif child.type == syms.import_as_names:
+                yield from get_imports_from_children(child.children)
+            else:
+                raise AssertionError("Invalid syntax parsing imports")
+
+    for child in node.children:
+        if child.type != syms.simple_stmt:
+            break
+        first_child = child.children[0]
+        if isinstance(first_child, Leaf):
+            # Continue looking if we see a docstring; otherwise stop.
+            if (
+                len(child.children) == 2
+                and first_child.type == token.STRING
+                and child.children[1].type == token.NEWLINE
+            ):
+                continue
+            else:
+                break
+        elif first_child.type == syms.import_from:
+            module_name = first_child.children[1]
+            if not isinstance(module_name, Leaf) or module_name.value != "__future__":
+                break
+            imports |= set(get_imports_from_children(first_child.children[3:]))
+        else:
+            break
+    return imports
+
+
+def gen_python_files_in_dir(
+    path: Path,
+    root: Path,
+    include: Pattern[str],
+    exclude: Pattern[str],
+    report: "Report",
+) -> Iterator[Path]:
+    """Generate all files under `path` whose paths are not excluded by the
+    `exclude` regex, but are included by the `include` regex.
+
+    Symbolic links pointing outside of the `root` directory are ignored.
+
+    `report` is where output about exclusions goes.
+    """
+    assert root.is_absolute(), f"INTERNAL ERROR: `root` must be absolute but is {root}"
+    for child in path.iterdir():
+        try:
+            normalized_path = "/" + child.resolve().relative_to(root).as_posix()
+        except ValueError:
+            if child.is_symlink():
+                report.path_ignored(
+                    child, f"is a symbolic link that points outside {root}"
+                )
+                continue
+
+            raise
+
+        if child.is_dir():
+            normalized_path += "/"
+        exclude_match = exclude.search(normalized_path)
+        if exclude_match and exclude_match.group(0):
+            report.path_ignored(child, f"matches the --exclude regular expression")
+            continue
+
+        if child.is_dir():
+            yield from gen_python_files_in_dir(child, root, include, exclude, report)
+
+        elif child.is_file():
+            include_match = include.search(normalized_path)
+            if include_match:
+                yield child
+
+
+@lru_cache()
+def find_project_root(srcs: Iterable[str]) -> Path:
+    """Return a directory containing .git, .hg, or pyproject.toml.
+
+    That directory can be one of the directories passed in `srcs` or their
+    common parent.
+
+    If no directory in the tree contains a marker that would specify it's the
+    project root, the root of the file system is returned.
+    """
+    if not srcs:
+        return Path("/").resolve()
+
+    common_base = min(Path(src).resolve() for src in srcs)
+    if common_base.is_dir():
+        # Append a fake file so `parents` below returns `common_base_dir`, too.
+        common_base /= "fake-file"
+    for directory in common_base.parents:
+        if (directory / ".git").is_dir():
+            return directory
+
+        if (directory / ".hg").is_dir():
+            return directory
+
+        if (directory / "pyproject.toml").is_file():
+            return directory
+
+    return directory
+
+
+@dataclass
+class Report:
+    """Provides a reformatting counter. Can be rendered with `str(report)`."""
+
+    check: bool = False
+    quiet: bool = False
+    verbose: bool = False
+    change_count: int = 0
+    same_count: int = 0
+    failure_count: int = 0
+
+    def done(self, src: Path, changed: Changed) -> None:
+        """Increment the counter for successful reformatting. Write out a message."""
+        if changed is Changed.YES:
+            reformatted = "would reformat" if self.check else "reformatted"
+            if self.verbose or not self.quiet:
+                out(f"{reformatted} {src}")
+            self.change_count += 1
+        else:
+            if self.verbose:
+                if changed is Changed.NO:
+                    msg = f"{src} already well formatted, good job."
+                else:
+                    msg = f"{src} wasn't modified on disk since last run."
+                out(msg, bold=False)
+            self.same_count += 1
+
+    def failed(self, src: Path, message: str) -> None:
+        """Increment the counter for failed reformatting. Write out a message."""
+        err(f"error: cannot format {src}: {message}")
+        self.failure_count += 1
+
+    def path_ignored(self, path: Path, message: str) -> None:
+        if self.verbose:
+            out(f"{path} ignored: {message}", bold=False)
+
+    @property
+    def return_code(self) -> int:
+        """Return the exit code that the app should use.
+
+        This considers the current state of changed files and failures:
+        - if there were any failures, return 123;
+        - if any files were changed and --check is being used, return 1;
+        - otherwise return 0.
+        """
+        # According to http://tldp.org/LDP/abs/html/exitcodes.html starting with
+        # 126 we have special return codes reserved by the shell.
+        if self.failure_count:
+            return 123
+
+        elif self.change_count and self.check:
+            return 1
+
+        return 0
+
+    def __str__(self) -> str:
+        """Render a color report of the current state.
+
+        Use `click.unstyle` to remove colors.
+        """
+        if self.check:
+            reformatted = "would be reformatted"
+            unchanged = "would be left unchanged"
+            failed = "would fail to reformat"
+        else:
+            reformatted = "reformatted"
+            unchanged = "left unchanged"
+            failed = "failed to reformat"
+        report = []
+        if self.change_count:
+            s = "s" if self.change_count > 1 else ""
+            report.append(
+                click.style(f"{self.change_count} file{s} {reformatted}", bold=True)
+            )
+        if self.same_count:
+            s = "s" if self.same_count > 1 else ""
+            report.append(f"{self.same_count} file{s} {unchanged}")
+        if self.failure_count:
+            s = "s" if self.failure_count > 1 else ""
+            report.append(
+                click.style(f"{self.failure_count} file{s} {failed}", fg="red")
+            )
+        return ", ".join(report) + "."
+
+
+def parse_ast(src: str) -> Union[ast.AST, ast3.AST, ast27.AST]:
+    filename = "<unknown>"
+    if sys.version_info >= (3, 8):
+        # TODO: support Python 4+ ;)
+        for minor_version in range(sys.version_info[1], 4, -1):
+            try:
+                return ast.parse(src, filename, feature_version=(3, minor_version))
+            except SyntaxError:
+                continue
+    else:
+        for feature_version in (7, 6):
+            try:
+                return ast3.parse(src, filename, feature_version=feature_version)
+            except SyntaxError:
+                continue
+
+    return ast27.parse(src)
+
+
+def _fixup_ast_constants(
+    node: Union[ast.AST, ast3.AST, ast27.AST]
+) -> Union[ast.AST, ast3.AST, ast27.AST]:
+    """Map ast nodes deprecated in 3.8 to Constant."""
+    # casts are required until this is released:
+    # https://github.com/python/typeshed/pull/3142
+    if isinstance(node, (ast.Str, ast3.Str, ast27.Str, ast.Bytes, ast3.Bytes)):
+        return cast(ast.AST, ast.Constant(value=node.s))
+    elif isinstance(node, (ast.Num, ast3.Num, ast27.Num)):
+        return cast(ast.AST, ast.Constant(value=node.n))
+    elif isinstance(node, (ast.NameConstant, ast3.NameConstant)):
+        return cast(ast.AST, ast.Constant(value=node.value))
+    return node
+
+
+def assert_equivalent(src: str, dst: str) -> None:
+    """Raise AssertionError if `src` and `dst` aren't equivalent."""
+
+    def _v(node: Union[ast.AST, ast3.AST, ast27.AST], depth: int = 0) -> Iterator[str]:
+        """Simple visitor generating strings to compare ASTs by content."""
+
+        node = _fixup_ast_constants(node)
+
+        yield f"{'  ' * depth}{node.__class__.__name__}("
+
+        for field in sorted(node._fields):
+            # TypeIgnore has only one field 'lineno' which breaks this comparison
+            type_ignore_classes = (ast3.TypeIgnore, ast27.TypeIgnore)
+            if sys.version_info >= (3, 8):
+                type_ignore_classes += (ast.TypeIgnore,)
+            if isinstance(node, type_ignore_classes):
+                break
+
+            try:
+                value = getattr(node, field)
+            except AttributeError:
+                continue
+
+            yield f"{'  ' * (depth+1)}{field}="
+
+            if isinstance(value, list):
+                for item in value:
+                    # Ignore nested tuples within del statements, because we may insert
+                    # parentheses and they change the AST.
+                    if (
+                        field == "targets"
+                        and isinstance(node, (ast.Delete, ast3.Delete, ast27.Delete))
+                        and isinstance(item, (ast.Tuple, ast3.Tuple, ast27.Tuple))
+                    ):
+                        for item in item.elts:
+                            yield from _v(item, depth + 2)
+                    elif isinstance(item, (ast.AST, ast3.AST, ast27.AST)):
+                        yield from _v(item, depth + 2)
+
+            elif isinstance(value, (ast.AST, ast3.AST, ast27.AST)):
+                yield from _v(value, depth + 2)
+
+            else:
+                yield f"{'  ' * (depth+2)}{value!r},  # {value.__class__.__name__}"
+
+        yield f"{'  ' * depth})  # /{node.__class__.__name__}"
+
+    try:
+        src_ast = parse_ast(src)
+    except Exception as exc:
+        raise AssertionError(
+            f"cannot use --safe with this file; failed to parse source file.  "
+            f"AST error message: {exc}"
+        )
+
+    try:
+        dst_ast = parse_ast(dst)
+    except Exception as exc:
+        log = dump_to_file("".join(traceback.format_tb(exc.__traceback__)), dst)
+        raise AssertionError(
+            f"INTERNAL ERROR: Black produced invalid code: {exc}. "
+            f"Please report a bug on https://github.com/psf/black/issues.  "
+            f"This invalid output might be helpful: {log}"
+        ) from None
+
+    src_ast_str = "\n".join(_v(src_ast))
+    dst_ast_str = "\n".join(_v(dst_ast))
+    if src_ast_str != dst_ast_str:
+        log = dump_to_file(diff(src_ast_str, dst_ast_str, "src", "dst"))
+        raise AssertionError(
+            f"INTERNAL ERROR: Black produced code that is not equivalent to "
+            f"the source.  "
+            f"Please report a bug on https://github.com/psf/black/issues.  "
+            f"This diff might be helpful: {log}"
+        ) from None
+
+
+def assert_stable(src: str, dst: str, mode: FileMode) -> None:
+    """Raise AssertionError if `dst` reformats differently the second time."""
+    newdst = format_str(dst, mode=mode)
+    if dst != newdst:
+        log = dump_to_file(
+            diff(src, dst, "source", "first pass"),
+            diff(dst, newdst, "first pass", "second pass"),
+        )
+        raise AssertionError(
+            f"INTERNAL ERROR: Black produced different code on the second pass "
+            f"of the formatter.  "
+            f"Please report a bug on https://github.com/psf/black/issues.  "
+            f"This diff might be helpful: {log}"
+        ) from None
+
+
+def dump_to_file(*output: str) -> str:
+    """Dump `output` to a temporary file. Return path to the file."""
+    with tempfile.NamedTemporaryFile(
+        mode="w", prefix="blk_", suffix=".log", delete=False, encoding="utf8"
+    ) as f:
+        for lines in output:
+            f.write(lines)
+            if lines and lines[-1] != "\n":
+                f.write("\n")
+    return f.name
+
+
+@contextmanager
+def nullcontext() -> Iterator[None]:
+    """Return context manager that does nothing.
+    Similar to `nullcontext` from python 3.7"""
+    yield
+
+
+def diff(a: str, b: str, a_name: str, b_name: str) -> str:
+    """Return a unified diff string between strings `a` and `b`."""
+    import difflib
+
+    a_lines = [line + "\n" for line in a.split("\n")]
+    b_lines = [line + "\n" for line in b.split("\n")]
+    return "".join(
+        difflib.unified_diff(a_lines, b_lines, fromfile=a_name, tofile=b_name, n=5)
+    )
+
+
+def cancel(tasks: Iterable[asyncio.Task]) -> None:
+    """asyncio signal handler that cancels all `tasks` and reports to stderr."""
+    err("Aborted!")
+    for task in tasks:
+        task.cancel()
+
+
+def shutdown(loop: asyncio.AbstractEventLoop) -> None:
+    """Cancel all pending tasks on `loop`, wait for them, and close the loop."""
+    try:
+        if sys.version_info[:2] >= (3, 7):
+            all_tasks = asyncio.all_tasks
+        else:
+            all_tasks = asyncio.Task.all_tasks
+        # This part is borrowed from asyncio/runners.py in Python 3.7b2.
+        to_cancel = [task for task in all_tasks(loop) if not task.done()]
+        if not to_cancel:
+            return
+
+        for task in to_cancel:
+            task.cancel()
+        loop.run_until_complete(
+            asyncio.gather(*to_cancel, loop=loop, return_exceptions=True)
+        )
+    finally:
+        # `concurrent.futures.Future` objects cannot be cancelled once they
+        # are already running. There might be some when the `shutdown()` happened.
+        # Silence their logger's spew about the event loop being closed.
+        cf_logger = logging.getLogger("concurrent.futures")
+        cf_logger.setLevel(logging.CRITICAL)
+        loop.close()
+
+
+def sub_twice(regex: Pattern[str], replacement: str, original: str) -> str:
+    """Replace `regex` with `replacement` twice on `original`.
+
+    This is used by string normalization to perform replaces on
+    overlapping matches.
+    """
+    return regex.sub(replacement, regex.sub(replacement, original))
+
+
+def re_compile_maybe_verbose(regex: str) -> Pattern[str]:
+    """Compile a regular expression string in `regex`.
+
+    If it contains newlines, use verbose mode.
+    """
+    if "\n" in regex:
+        regex = "(?x)" + regex
+    return re.compile(regex)
+
+
+def enumerate_reversed(sequence: Sequence[T]) -> Iterator[Tuple[Index, T]]:
+    """Like `reversed(enumerate(sequence))` if that were possible."""
+    index = len(sequence) - 1
+    for element in reversed(sequence):
+        yield (index, element)
+        index -= 1
+
+
+def enumerate_with_length(
+    line: Line, reversed: bool = False
+) -> Iterator[Tuple[Index, Leaf, int]]:
+    """Return an enumeration of leaves with their length.
+
+    Stops prematurely on multiline strings and standalone comments.
+    """
+    op = cast(
+        Callable[[Sequence[Leaf]], Iterator[Tuple[Index, Leaf]]],
+        enumerate_reversed if reversed else enumerate,
+    )
+    for index, leaf in op(line.leaves):
+        length = len(leaf.prefix) + len(leaf.value)
+        if "\n" in leaf.value:
+            return  # Multiline strings, we can't continue.
+
+        for comment in line.comments_after(leaf):
+            length += len(comment.value)
+
+        yield index, leaf, length
+
+
+def is_line_short_enough(line: Line, *, line_length: int, line_str: str = "") -> bool:
+    """Return True if `line` is no longer than `line_length`.
+
+    Uses the provided `line_str` rendering, if any, otherwise computes a new one.
+    """
+    if not line_str:
+        line_str = str(line).strip("\n")
+    return (
+        len(line_str) <= line_length
+        and "\n" not in line_str  # multiline strings
+        and not line.contains_standalone_comments()
+    )
+
+
+def can_be_split(line: Line) -> bool:
+    """Return False if the line cannot be split *for sure*.
+
+    This is not an exhaustive search but a cheap heuristic that we can use to
+    avoid some unfortunate formattings (mostly around wrapping unsplittable code
+    in unnecessary parentheses).
+    """
+    leaves = line.leaves
+    if len(leaves) < 2:
+        return False
+
+    if leaves[0].type == token.STRING and leaves[1].type == token.DOT:
+        call_count = 0
+        dot_count = 0
+        next = leaves[-1]
+        for leaf in leaves[-2::-1]:
+            if leaf.type in OPENING_BRACKETS:
+                if next.type not in CLOSING_BRACKETS:
+                    return False
+
+                call_count += 1
+            elif leaf.type == token.DOT:
+                dot_count += 1
+            elif leaf.type == token.NAME:
+                if not (next.type == token.DOT or next.type in OPENING_BRACKETS):
+                    return False
+
+            elif leaf.type not in CLOSING_BRACKETS:
+                return False
+
+            if dot_count > 1 and call_count > 1:
+                return False
+
+    return True
+
+
+def can_omit_invisible_parens(line: Line, line_length: int) -> bool:
+    """Does `line` have a shape safe to reformat without optional parens around it?
+
+    Returns True for only a subset of potentially nice looking formattings but
+    the point is to not return false positives that end up producing lines that
+    are too long.
+    """
+    bt = line.bracket_tracker
+    if not bt.delimiters:
+        # Without delimiters the optional parentheses are useless.
+        return True
+
+    max_priority = bt.max_delimiter_priority()
+    if bt.delimiter_count_with_priority(max_priority) > 1:
+        # With more than one delimiter of a kind the optional parentheses read better.
+        return False
+
+    if max_priority == DOT_PRIORITY:
+        # A single stranded method call doesn't require optional parentheses.
+        return True
+
+    assert len(line.leaves) >= 2, "Stranded delimiter"
+
+    first = line.leaves[0]
+    second = line.leaves[1]
+    penultimate = line.leaves[-2]
+    last = line.leaves[-1]
+
+    # With a single delimiter, omit if the expression starts or ends with
+    # a bracket.
+    if first.type in OPENING_BRACKETS and second.type not in CLOSING_BRACKETS:
+        remainder = False
+        length = 4 * line.depth
+        for _index, leaf, leaf_length in enumerate_with_length(line):
+            if leaf.type in CLOSING_BRACKETS and leaf.opening_bracket is first:
+                remainder = True
+            if remainder:
+                length += leaf_length
+                if length > line_length:
+                    break
+
+                if leaf.type in OPENING_BRACKETS:
+                    # There are brackets we can further split on.
+                    remainder = False
+
+        else:
+            # checked the entire string and line length wasn't exceeded
+            if len(line.leaves) == _index + 1:
+                return True
+
+        # Note: we are not returning False here because a line might have *both*
+        # a leading opening bracket and a trailing closing bracket.  If the
+        # opening bracket doesn't match our rule, maybe the closing will.
+
+    if (
+        last.type == token.RPAR
+        or last.type == token.RBRACE
+        or (
+            # don't use indexing for omitting optional parentheses;
+            # it looks weird
+            last.type == token.RSQB
+            and last.parent
+            and last.parent.type != syms.trailer
+        )
+    ):
+        if penultimate.type in OPENING_BRACKETS:
+            # Empty brackets don't help.
+            return False
+
+        if is_multiline_string(first):
+            # Additional wrapping of a multiline string in this situation is
+            # unnecessary.
+            return True
+
+        length = 4 * line.depth
+        seen_other_brackets = False
+        for _index, leaf, leaf_length in enumerate_with_length(line):
+            length += leaf_length
+            if leaf is last.opening_bracket:
+                if seen_other_brackets or length <= line_length:
+                    return True
+
+            elif leaf.type in OPENING_BRACKETS:
+                # There are brackets we can further split on.
+                seen_other_brackets = True
+
+    return False
+
+
+def get_cache_file(mode: FileMode) -> Path:
+    return CACHE_DIR / f"cache.{mode.get_cache_key()}.pickle"
+
+
+def read_cache(mode: FileMode) -> Cache:
+    """Read the cache if it exists and is well formed.
+
+    If it is not well formed, the call to write_cache later should resolve the issue.
+    """
+    cache_file = get_cache_file(mode)
+    if not cache_file.exists():
+        return {}
+
+    with cache_file.open("rb") as fobj:
+        try:
+            cache: Cache = pickle.load(fobj)
+        except pickle.UnpicklingError:
+            return {}
+
+    return cache
+
+
+def get_cache_info(path: Path) -> CacheInfo:
+    """Return the information used to check if a file is already formatted or not."""
+    stat = path.stat()
+    return stat.st_mtime, stat.st_size
+
+
+def filter_cached(cache: Cache, sources: Iterable[Path]) -> Tuple[Set[Path], Set[Path]]:
+    """Split an iterable of paths in `sources` into two sets.
+
+    The first contains paths of files that modified on disk or are not in the
+    cache. The other contains paths to non-modified files.
+    """
+    todo, done = set(), set()
+    for src in sources:
+        src = src.resolve()
+        if cache.get(src) != get_cache_info(src):
+            todo.add(src)
+        else:
+            done.add(src)
+    return todo, done
+
+
+def write_cache(cache: Cache, sources: Iterable[Path], mode: FileMode) -> None:
+    """Update the cache file."""
+    cache_file = get_cache_file(mode)
+    try:
+        CACHE_DIR.mkdir(parents=True, exist_ok=True)
+        new_cache = {**cache, **{src.resolve(): get_cache_info(src) for src in sources}}
+        with tempfile.NamedTemporaryFile(dir=str(cache_file.parent), delete=False) as f:
+            pickle.dump(new_cache, f, protocol=pickle.HIGHEST_PROTOCOL)
+        os.replace(f.name, cache_file)
+    except OSError:
+        pass
+
+
+def patch_click() -> None:
+    """Make Click not crash.
+
+    On certain misconfigured environments, Python 3 selects the ASCII encoding as the
+    default which restricts paths that it can access during the lifetime of the
+    application.  Click refuses to work in this scenario by raising a RuntimeError.
+
+    In case of Black the likelihood that non-ASCII characters are going to be used in
+    file paths is minimal since it's Python source code.  Moreover, this crash was
+    spurious on Python 3.7 thanks to PEP 538 and PEP 540.
+    """
+    try:
+        from click import core
+        from click import _unicodefun  # type: ignore
+    except ModuleNotFoundError:
+        return
+
+    for module in (core, _unicodefun):
+        if hasattr(module, "_verify_python3_env"):
+            module._verify_python3_env = lambda: None
+
+
+def patched_main() -> None:
+    freeze_support()
+    patch_click()
+    main()
+
+
+if __name__ == "__main__":
+    patched_main()

Makefile

@@ -113,7 +113,7 b' check: tests'
 tests:
         # Run Rust tests if cargo is installed
 	if command -v $(CARGO) >/dev/null 2>&1; then \
-		cd $(HGROOT)/rust/hg-cpython && $(CARGO) test --quiet --all; \
+		$(MAKE) rust-tests; \
 	fi
 	cd tests && $(PYTHON) run-tests.py $(TESTFLAGS)
 
@@ -127,6 +127,13 b' testpy-%:'
         $(MAKE) -f $(HGROOT)/contrib/Makefile.python PYTHONVER=$* PREFIX=$(HGPYTHONS)/$* python )
 	cd tests && $(HGPYTHONS)/$*/bin/python run-tests.py $(TESTFLAGS)
 
+rust-tests: py_feature = $(shell $(PYTHON) -c \
+ 'import sys; print(["python27-bin", "python3-bin"][sys.version_info[0] >= 3])')
+rust-tests:
+	cd $(HGROOT)/rust/hg-cpython \
+		&& $(CARGO) test --quiet --all \
+			--no-default-features --features "$(py_feature)"
+
 check-code:
 	hg manifest | xargs python contrib/check-code.py
 
@@ -248,6 +255,7 b' osx:'
 
 .PHONY: help all local build doc cleanbutpackages clean install install-bin \
 	install-doc install-home install-home-bin install-home-doc \
-	dist dist-notests check tests check-code format-c update-pot \
+	dist dist-notests check tests rust-tests check-code format-c \
+	update-pot \
 	$(packaging_targets) \
 	osx

contrib/automation/README.rst

@@ -33,6 +33,46 b" side-effects so they don't impact the lo"
 into a remote machine, we create a temporary directory for the SSH
 config so the user's known hosts file isn't updated.
 
+Try Server
+==========
+
+There exists a *Try Server* which allows automation to run against
+an arbitrary Mercurial changeset and displays results via the web.
+
+.. note::
+
+   The *Try Server* is still experimental infrastructure.
+
+To use the *Try Server*::
+
+   $ ./automation.py try
+
+With a custom AWS profile::
+
+   $ AWS_PROFILE=hg contrib/automation/automation.py try
+
+By default, the ``.`` revision is submitted. **Any uncommitted changes
+are not submitted.**
+
+To switch which revision is used::
+
+   $ ./automation.py try -r abcdef
+
+Access to the *Try Server* requires access to a special AWS account.
+This account is currently run by Gregory Szorc. Here is the procedure
+for accessing the *Try Server*:
+
+1. Email Gregory Szorc at [e-mail] and request a
+   username. This username will be stored in the public domain.
+2. Wait for an email reply containing your temporary AWS credentials.
+3. Log in at https://gregoryszorc-hg.signin.aws.amazon.com/console
+   and set a new, secure password.
+4. Go to https://console.aws.amazon.com/iam/home?region=us-west-2#/security_credentials
+5. Under ``Access keys for CLI, SDK, & API access``, click the
+   ``Create access key`` button.
+6. See the ``AWS Integration`` section for instructions on
+   configuring your local client to use the generated credentials.
+
 AWS Integration
 ===============
 
@@ -47,12 +87,25 b' https://boto3.amazonaws.com/v1/documenta'
 for how ``boto3`` works. Once you have configured your environment such
 that ``boto3`` can find credentials, interaction with AWS should *just work*.
 
-.. hint::
+To configure ``boto3``, you can use the ``aws configure`` command to
+write out configuration files. (The ``aws`` command is typically provided
+by an ``awscli`` package available in your package manager, including
+``pip``.) Alternatively, you can write out files in ``~/.aws/`` directly.
+e.g.::
+
+   # ~/.aws/config
+   [default]
+   region = us-west-2
 
-   Typically you have a ``~/.aws/credentials`` file containing AWS
-   credentials. If you manage multiple credentials, you can override which
-   *profile* to use at run-time by setting the ``AWS_PROFILE`` environment
-   variable.
+   # ~/.aws/credentials
+   [default]
+   aws_access_key_id = XXXX
+   aws_secret_access_key = YYYY
+
+If you have multiple AWS accounts, you can name the profile something
+different from ``default``. e.g. ``hg``. You can influence which profile
+is used by ``boto3`` by setting the ``AWS_PROFILE`` environment variable.
+e.g. ``AWS_PROFILE=hg``.
 
 Resource Management
 -------------------
@@ -181,3 +234,25 b' Various dependencies to run the Mercuria'
 Documenting them is beyond the scope of this document. Various tests
 also require other optional dependencies and missing dependencies will
 be printed by the test runner when a test is skipped.
+
+Releasing Windows Artifacts
+===========================
+
+The `automation.py` script can be used to automate the release of Windows
+artifacts::
+
+   $ ./automation.py build-all-windows-packages --revision 5.1.1
+   $ ./automation.py publish-windows-artifacts 5.1.1
+
+The first command will launch an EC2 instance to build all Windows packages
+and copy them into the `dist` directory relative to the repository root. The
+second command will then attempt to upload these files to PyPI (via `twine`)
+and to `mercurial-scm.org` (via SSH).
+
+Uploading to PyPI requires a PyPI account with write access to the `Mercurial`
+package. You can skip PyPI uploading by passing `--no-pypi`.
+
+Uploading to `mercurial-scm.org` requires an SSH account on that server
+with `windows` group membership and for the SSH key for that account to be the
+default SSH key (e.g. `~/.ssh/id_rsa`) or in a running SSH agent. You can
+skip `mercurial-scm.org` uploading by passing `--no-mercurial-scm-org`.

contrib/automation/automation.py

@@ -36,8 +36,13 b' def bootstrap():'
         pip = venv_bin / 'pip'
         python = venv_bin / 'python'
 
-    args = [str(pip), 'install', '-r', str(REQUIREMENTS_TXT),
-            '--disable-pip-version-check']
+    args = [
+        str(pip),
+        'install',
+        '-r',
+        str(REQUIREMENTS_TXT),
+        '--disable-pip-version-check',
+    ]
 
     if not venv_created:
         args.append('-q')
@@ -45,8 +50,7 b' def bootstrap():'
     subprocess.run(args, check=True)
 
     os.environ['HGAUTOMATION_BOOTSTRAPPED'] = '1'
-    os.environ['PATH'] = '%s%s%s' % (
-        venv_bin, os.pathsep, os.environ['PATH'])
+    os.environ['PATH'] = '%s%s%s' % (venv_bin, os.pathsep, os.environ['PATH'])
 
     subprocess.run([str(python), __file__] + sys.argv[1:], check=True)
 

contrib/automation/hgautomation/__init__.py

@@ -10,9 +10,7 b''
 import pathlib
 import secrets
 
-from .aws import (
-    AWSConnection,
-)
+from .aws import AWSConnection
 
 
 class HGAutomation:
@@ -53,7 +51,7 b' class HGAutomation:'
 
         return password
 
-    def aws_connection(self, region: str, ensure_ec2_state: bool=True):
+    def aws_connection(self, region: str, ensure_ec2_state: bool = True):
         """Obtain an AWSConnection instance bound to a specific region."""
 
         return AWSConnection(self, region, ensure_ec2_state=ensure_ec2_state)

contrib/automation/hgautomation/aws.py

@@ -19,9 +19,7 b' import time'
 import boto3
 import botocore.exceptions
 
-from .linux import (
-    BOOTSTRAP_DEBIAN,
-)
+from .linux import BOOTSTRAP_DEBIAN
 from .ssh import (
     exec_command as ssh_exec_command,
     wait_for_ssh,
@@ -32,10 +30,13 b' from .winrm import ('
 )
 
 
-SOURCE_ROOT = pathlib.Path(os.path.abspath(__file__)).parent.parent.parent.parent
+SOURCE_ROOT = pathlib.Path(
+    os.path.abspath(__file__)
+).parent.parent.parent.parent
 
-INSTALL_WINDOWS_DEPENDENCIES = (SOURCE_ROOT / 'contrib' /
-                                'install-windows-dependencies.ps1')
+INSTALL_WINDOWS_DEPENDENCIES = (
+    SOURCE_ROOT / 'contrib' / 'install-windows-dependencies.ps1'
+)
 
 
 INSTANCE_TYPES_WITH_STORAGE = {
@@ -54,6 +55,7 b' INSTANCE_TYPES_WITH_STORAGE = {'
 
 AMAZON_ACCOUNT_ID = '801119661308'
 DEBIAN_ACCOUNT_ID = '379101102735'
+DEBIAN_ACCOUNT_ID_2 = '136693071363'
 UBUNTU_ACCOUNT_ID = '099720109477'
 
 
@@ -106,7 +108,6 b' SECURITY_GROUPS = {'
                         'Description': 'RDP from entire Internet',
                     },
                 ],
-
             },
             {
                 'FromPort': 5985,
@@ -118,7 +119,7 b' SECURITY_GROUPS = {'
                         'Description': 'PowerShell Remoting (Windows Remote Management)',
                     },
                 ],
-            }
+            },
         ],
     },
 }
@@ -151,11 +152,7 b" ASSUME_ROLE_POLICY_DOCUMENT = '''"
 
 
 IAM_INSTANCE_PROFILES = {
-    'ephemeral-ec2-1': {
-        'roles': [
-            'ephemeral-ec2-role-1',
-        ],
-    }
+    'ephemeral-ec2-1': {'roles': ['ephemeral-ec2-role-1',],}
 }
 
 
@@ -225,7 +222,7 b' Install-WindowsFeature -Name Net-Framewo'
 class AWSConnection:
     """Manages the state of a connection with AWS."""
 
-    def __init__(self, automation, region: str, ensure_ec2_state: bool=True):
+    def __init__(self, automation, region: str, ensure_ec2_state: bool = True):
         self.automation = automation
         self.local_state_path = automation.state_path
 
@@ -256,10 +253,19 b' def rsa_key_fingerprint(p: pathlib.Path)'
 
     # TODO use rsa package.
     res = subprocess.run(
-        ['openssl', 'pkcs8', '-in', str(p), '-nocrypt', '-topk8',
-         '-outform', 'DER'],
+        [
+            'openssl',
+            'pkcs8',
+            '-in',
+            str(p),
+            '-nocrypt',
+            '-topk8',
+            '-outform',
+            'DER',
+        ],
         capture_output=True,
-        check=True)
+        check=True,
+    )
 
     sha1 = hashlib.sha1(res.stdout).hexdigest()
     return ':'.join(a + b for a, b in zip(sha1[::2], sha1[1::2]))
@@ -270,7 +276,7 b' def ensure_key_pairs(state_path: pathlib'
 
     for kpi in ec2resource.key_pairs.all():
         if kpi.name.startswith(prefix):
-            remote_existing[kpi.name[len(prefix):]] = kpi.key_fingerprint
+            remote_existing[kpi.name[len(prefix) :]] = kpi.key_fingerprint
 
     # Validate that we have these keys locally.
     key_path = state_path / 'keys'
@@ -296,7 +302,7 b' def ensure_key_pairs(state_path: pathlib'
         if not f.startswith('keypair-') or not f.endswith('.pub'):
             continue
 
-        name = f[len('keypair-'):-len('.pub')]
+        name = f[len('keypair-') : -len('.pub')]
 
         pub_full = key_path / f
         priv_full = key_path / ('keypair-%s' % name)
@@ -305,8 +311,9 b' def ensure_key_pairs(state_path: pathlib'
             data = fh.read()
 
         if not data.startswith('ssh-rsa '):
-            print('unexpected format for key pair file: %s; removing' %
-                  pub_full)
+            print(
+                'unexpected format for key pair file: %s; removing' % pub_full
+            )
             pub_full.unlink()
             priv_full.unlink()
             continue
@@ -326,8 +333,10 b' def ensure_key_pairs(state_path: pathlib'
             del local_existing[name]
 
         elif remote_existing[name] != local_existing[name]:
-            print('key fingerprint mismatch for %s; '
-                  'removing from local and remote' % name)
+            print(
+                'key fingerprint mismatch for %s; '
+                'removing from local and remote' % name
+            )
             remove_local(name)
             remove_remote('%s%s' % (prefix, name))
             del local_existing[name]
@@ -355,15 +364,18 b' def ensure_key_pairs(state_path: pathlib'
             subprocess.run(
                 ['ssh-keygen', '-y', '-f', str(priv_full)],
                 stdout=fh,
-                check=True)
+                check=True,
+            )
 
         pub_full.chmod(0o0600)
 
 
 def delete_instance_profile(profile):
     for role in profile.roles:
-        print('removing role %s from instance profile %s' % (role.name,
-                                                             profile.name))
+        print(
+            'removing role %s from instance profile %s'
+            % (role.name, profile.name)
+        )
         profile.remove_role(RoleName=role.name)
 
     print('deleting instance profile %s' % profile.name)
@@ -377,7 +389,7 b' def ensure_iam_state(iamclient, iamresou'
 
     for profile in iamresource.instance_profiles.all():
         if profile.name.startswith(prefix):
-            remote_profiles[profile.name[len(prefix):]] = profile
+            remote_profiles[profile.name[len(prefix) :]] = profile
 
     for name in sorted(set(remote_profiles) - set(IAM_INSTANCE_PROFILES)):
         delete_instance_profile(remote_profiles[name])
@@ -387,7 +399,7 b' def ensure_iam_state(iamclient, iamresou'
 
     for role in iamresource.roles.all():
         if role.name.startswith(prefix):
-            remote_roles[role.name[len(prefix):]] = role
+            remote_roles[role.name[len(prefix) :]] = role
 
     for name in sorted(set(remote_roles) - set(IAM_ROLES)):
         role = remote_roles[name]
@@ -403,7 +415,8 b' def ensure_iam_state(iamclient, iamresou'
         print('creating IAM instance profile %s' % actual)
 
         profile = iamresource.create_instance_profile(
-            InstanceProfileName=actual)
+            InstanceProfileName=actual
+        )
         remote_profiles[name] = profile
 
         waiter = iamclient.get_waiter('instance_profile_exists')
@@ -452,23 +465,12 b' def find_image(ec2resource, owner_id, na'
 
     images = ec2resource.images.filter(
         Filters=[
-            {
-                'Name': 'owner-id',
-                'Values': [owner_id],
-            },
-            {
-                'Name': 'state',
-                'Values': ['available'],
-            },
-            {
-                'Name': 'image-type',
-                'Values': ['machine'],
-            },
-            {
-                'Name': 'name',
-                'Values': [name],
-            },
-        ])
+            {'Name': 'owner-id', 'Values': [owner_id],},
+            {'Name': 'state', 'Values': ['available'],},
+            {'Name': 'image-type', 'Values': ['machine'],},
+            {'Name': 'name', 'Values': [name],},
+        ]
+    )
 
     for image in images:
         return image
@@ -486,7 +488,7 b' def ensure_security_groups(ec2resource, '
 
     for group in ec2resource.security_groups.all():
         if group.group_name.startswith(prefix):
-            existing[group.group_name[len(prefix):]] = group
+            existing[group.group_name[len(prefix) :]] = group
 
     purge = set(existing) - set(SECURITY_GROUPS)
 
@@ -506,13 +508,10 b' def ensure_security_groups(ec2resource, '
         print('adding security group %s' % actual)
 
         group_res = ec2resource.create_security_group(
-            Description=group['description'],
-            GroupName=actual,
+            Description=group['description'], GroupName=actual,
         )
 
-        group_res.authorize_ingress(
-            IpPermissions=group['ingress'],
-        )
+        group_res.authorize_ingress(IpPermissions=group['ingress'],)
 
         security_groups[name] = group_res
 
@@ -576,8 +575,10 b' def wait_for_ip_addresses(instances):'
                 instance.reload()
                 continue
 
-            print('public IP address for %s: %s' % (
-                instance.id, instance.public_ip_address))
+            print(
+                'public IP address for %s: %s'
+                % (instance.id, instance.public_ip_address)
+            )
             break
 
 
@@ -602,10 +603,7 b' def wait_for_ssm(ssmclient, instances):'
     while True:
         res = ssmclient.describe_instance_information(
             Filters=[
-                {
-                    'Key': 'InstanceIds',
-                    'Values': [i.id for i in instances],
-                },
+                {'Key': 'InstanceIds', 'Values': [i.id for i in instances],},
             ],
         )
 
@@ -627,9 +625,7 b' def run_ssm_command(ssmclient, instances'
         InstanceIds=[i.id for i in instances],
         DocumentName=document_name,
         Parameters=parameters,
-        CloudWatchOutputConfig={
-            'CloudWatchOutputEnabled': True,
-        },
+        CloudWatchOutputConfig={'CloudWatchOutputEnabled': True,},
     )
 
     command_id = res['Command']['CommandId']
@@ -638,8 +634,7 b' def run_ssm_command(ssmclient, instances'
         while True:
             try:
                 res = ssmclient.get_command_invocation(
-                    CommandId=command_id,
-                    InstanceId=instance.id,
+                    CommandId=command_id, InstanceId=instance.id,
                 )
             except botocore.exceptions.ClientError as e:
                 if e.response['Error']['Code'] == 'InvocationDoesNotExist':
@@ -654,8 +649,9 b' def run_ssm_command(ssmclient, instances'
             elif res['Status'] in ('Pending', 'InProgress', 'Delayed'):
                 time.sleep(2)
             else:
-                raise Exception('command failed on %s: %s' % (
-                    instance.id, res['Status']))
+                raise Exception(
+                    'command failed on %s: %s' % (instance.id, res['Status'])
+                )
 
 
 @contextlib.contextmanager
@@ -691,7 +687,9 b' def temporary_ec2_instances(ec2resource,'
 
 
 @contextlib.contextmanager
-def create_temp_windows_ec2_instances(c: AWSConnection, config):
+def create_temp_windows_ec2_instances(
+    c: AWSConnection, config, bootstrap: bool = False
+):
     """Create temporary Windows EC2 instances.
 
     This is a higher-level wrapper around ``create_temp_ec2_instances()`` that
@@ -710,11 +708,15 b' def create_temp_windows_ec2_instances(c:'
     config['IamInstanceProfile'] = {
         'Name': 'hg-ephemeral-ec2-1',
     }
-    config.setdefault('TagSpecifications', []).append({
-        'ResourceType': 'instance',
-        'Tags': [{'Key': 'Name', 'Value': 'hg-temp-windows'}],
-    })
-    config['UserData'] = WINDOWS_USER_DATA % password
+    config.setdefault('TagSpecifications', []).append(
+        {
+            'ResourceType': 'instance',
+            'Tags': [{'Key': 'Name', 'Value': 'hg-temp-windows'}],
+        }
+    )
+
+    if bootstrap:
+        config['UserData'] = WINDOWS_USER_DATA % password
 
     with temporary_ec2_instances(c.ec2resource, config) as instances:
         wait_for_ip_addresses(instances)
@@ -722,7 +724,9 b' def create_temp_windows_ec2_instances(c:'
         print('waiting for Windows Remote Management service...')
 
         for instance in instances:
-            client = wait_for_winrm(instance.public_ip_address, 'Administrator', password)
+            client = wait_for_winrm(
+                instance.public_ip_address, 'Administrator', password
+            )
             print('established WinRM connection to %s' % instance.id)
             instance.winrm_client = client
 
@@ -747,14 +751,17 b' def find_and_reconcile_image(ec2resource'
     # Store a reference to a good image so it can be returned one the
     # image state is reconciled.
     images = ec2resource.images.filter(
-        Filters=[{'Name': 'name', 'Values': [name]}])
+        Filters=[{'Name': 'name', 'Values': [name]}]
+    )
 
     existing_image = None
 
     for image in images:
         if image.tags is None:
-            print('image %s for %s lacks required tags; removing' % (
-                image.id, image.name))
+            print(
+                'image %s for %s lacks required tags; removing'
+                % (image.id, image.name)
+            )
             remove_ami(ec2resource, image)
         else:
             tags = {t['Key']: t['Value'] for t in image.tags}
@@ -762,15 +769,18 b' def find_and_reconcile_image(ec2resource'
             if tags.get('HGIMAGEFINGERPRINT') == fingerprint:
                 existing_image = image
             else:
-                print('image %s for %s has wrong fingerprint; removing' % (
-                      image.id, image.name))
+                print(
+                    'image %s for %s has wrong fingerprint; removing'
+                    % (image.id, image.name)
+                )
                 remove_ami(ec2resource, image)
 
     return existing_image
 
 
-def create_ami_from_instance(ec2client, instance, name, description,
-                             fingerprint):
+def create_ami_from_instance(
+    ec2client, instance, name, description, fingerprint
+):
     """Create an AMI from a running instance.
 
     Returns the ``ec2resource.Image`` representing the created AMI.
@@ -778,36 +788,26 b' def create_ami_from_instance(ec2client, '
     instance.stop()
 
     ec2client.get_waiter('instance_stopped').wait(
-        InstanceIds=[instance.id],
-        WaiterConfig={
-            'Delay': 5,
-        })
+        InstanceIds=[instance.id], WaiterConfig={'Delay': 5,}
+    )
     print('%s is stopped' % instance.id)
 
-    image = instance.create_image(
-        Name=name,
-        Description=description,
-    )
+    image = instance.create_image(Name=name, Description=description,)
 
-    image.create_tags(Tags=[
-        {
-            'Key': 'HGIMAGEFINGERPRINT',
-            'Value': fingerprint,
-        },
-    ])
+    image.create_tags(
+        Tags=[{'Key': 'HGIMAGEFINGERPRINT', 'Value': fingerprint,},]
+    )
 
     print('waiting for image %s' % image.id)
 
-    ec2client.get_waiter('image_available').wait(
-        ImageIds=[image.id],
-    )
+    ec2client.get_waiter('image_available').wait(ImageIds=[image.id],)
 
     print('image %s available as %s' % (image.id, image.name))
 
     return image
 
 
-def ensure_linux_dev_ami(c: AWSConnection, distro='debian9', prefix='hg-'):
+def ensure_linux_dev_ami(c: AWSConnection, distro='debian10', prefix='hg-'):
     """Ensures a Linux development AMI is available and up-to-date.
 
     Returns an ``ec2.Image`` of either an existing AMI or a newly-built one.
@@ -821,28 +821,26 b' def ensure_linux_dev_ami(c: AWSConnectio'
         image = find_image(
             ec2resource,
             DEBIAN_ACCOUNT_ID,
-            'debian-stretch-hvm-x86_64-gp2-2019-02-19-26620',
+            'debian-stretch-hvm-x86_64-gp2-2019-09-08-17994',
+        )
+        ssh_username = 'admin'
+    elif distro == 'debian10':
+        image = find_image(
+            ec2resource, DEBIAN_ACCOUNT_ID_2, 'debian-10-amd64-20190909-10',
         )
         ssh_username = 'admin'
     elif distro == 'ubuntu18.04':
         image = find_image(
             ec2resource,
             UBUNTU_ACCOUNT_ID,
-            'ubuntu/images/hvm-ssd/ubuntu-bionic-18.04-amd64-server-20190403',
-        )
-        ssh_username = 'ubuntu'
-    elif distro == 'ubuntu18.10':
-        image = find_image(
-            ec2resource,
-            UBUNTU_ACCOUNT_ID,
-            'ubuntu/images/hvm-ssd/ubuntu-cosmic-18.10-amd64-server-20190402',
+            'ubuntu/images/hvm-ssd/ubuntu-bionic-18.04-amd64-server-20190918',
         )
         ssh_username = 'ubuntu'
     elif distro == 'ubuntu19.04':
         image = find_image(
             ec2resource,
             UBUNTU_ACCOUNT_ID,
-            'ubuntu/images/hvm-ssd/ubuntu-disco-19.04-amd64-server-20190417',
+            'ubuntu/images/hvm-ssd/ubuntu-disco-19.04-amd64-server-20190918',
         )
         ssh_username = 'ubuntu'
     else:
@@ -854,7 +852,7 b' def ensure_linux_dev_ami(c: AWSConnectio'
                 'DeviceName': image.block_device_mappings[0]['DeviceName'],
                 'Ebs': {
                     'DeleteOnTermination': True,
-                    'VolumeSize': 8,
+                    'VolumeSize': 10,
                     'VolumeType': 'gp2',
                 },
             },
@@ -870,10 +868,12 b' def ensure_linux_dev_ami(c: AWSConnectio'
         'SecurityGroupIds': [c.security_groups['linux-dev-1'].id],
     }
 
-    requirements2_path = (pathlib.Path(__file__).parent.parent /
-                          'linux-requirements-py2.txt')
-    requirements3_path = (pathlib.Path(__file__).parent.parent /
-                          'linux-requirements-py3.txt')
+    requirements2_path = (
+        pathlib.Path(__file__).parent.parent / 'linux-requirements-py2.txt'
+    )
+    requirements3_path = (
+        pathlib.Path(__file__).parent.parent / 'linux-requirements-py3.txt'
+    )
     with requirements2_path.open('r', encoding='utf-8') as fh:
         requirements2 = fh.read()
     with requirements3_path.open('r', encoding='utf-8') as fh:
@@ -881,12 +881,14 b' def ensure_linux_dev_ami(c: AWSConnectio'
 
     # Compute a deterministic fingerprint to determine whether image needs to
     # be regenerated.
-    fingerprint = resolve_fingerprint({
-        'instance_config': config,
-        'bootstrap_script': BOOTSTRAP_DEBIAN,
-        'requirements_py2': requirements2,
-        'requirements_py3': requirements3,
-    })
+    fingerprint = resolve_fingerprint(
+        {
+            'instance_config': config,
+            'bootstrap_script': BOOTSTRAP_DEBIAN,
+            'requirements_py2': requirements2,
+            'requirements_py3': requirements3,
+        }
+    )
 
     existing_image = find_and_reconcile_image(ec2resource, name, fingerprint)
 
@@ -901,9 +903,11 b' def ensure_linux_dev_ami(c: AWSConnectio'
         instance = instances[0]
 
         client = wait_for_ssh(
-            instance.public_ip_address, 22,
+            instance.public_ip_address,
+            22,
             username=ssh_username,
-            key_filename=str(c.key_pair_path_private('automation')))
+            key_filename=str(c.key_pair_path_private('automation')),
+        )
 
         home = '/home/%s' % ssh_username
 
@@ -925,8 +929,9 b' def ensure_linux_dev_ami(c: AWSConnectio'
                 fh.chmod(0o0700)
 
             print('executing bootstrap')
-            chan, stdin, stdout = ssh_exec_command(client,
-                                                   '%s/bootstrap' % home)
+            chan, stdin, stdout = ssh_exec_command(
+                client, '%s/bootstrap' % home
+            )
             stdin.close()
 
             for line in stdout:
@@ -936,17 +941,28 b' def ensure_linux_dev_ami(c: AWSConnectio'
             if res:
                 raise Exception('non-0 exit from bootstrap: %d' % res)
 
-            print('bootstrap completed; stopping %s to create %s' % (
-                  instance.id, name))
+            print(
+                'bootstrap completed; stopping %s to create %s'
+                % (instance.id, name)
+            )
 
-        return create_ami_from_instance(ec2client, instance, name,
-                                        'Mercurial Linux development environment',
-                                        fingerprint)
+        return create_ami_from_instance(
+            ec2client,
+            instance,
+            name,
+            'Mercurial Linux development environment',
+            fingerprint,
+        )
 
 
 @contextlib.contextmanager
-def temporary_linux_dev_instances(c: AWSConnection, image, instance_type,
-                                  prefix='hg-', ensure_extra_volume=False):
+def temporary_linux_dev_instances(
+    c: AWSConnection,
+    image,
+    instance_type,
+    prefix='hg-',
+    ensure_extra_volume=False,
+):
     """Create temporary Linux development EC2 instances.
 
     Context manager resolves to a list of ``ec2.Instance`` that were created
@@ -970,7 +986,7 b' def temporary_linux_dev_instances(c: AWS'
             'DeviceName': image.block_device_mappings[0]['DeviceName'],
             'Ebs': {
                 'DeleteOnTermination': True,
-                'VolumeSize': 8,
+                'VolumeSize': 12,
                 'VolumeType': 'gp2',
             },
         }
@@ -978,8 +994,9 b' def temporary_linux_dev_instances(c: AWS'
 
     # This is not an exhaustive list of instance types having instance storage.
     # But
-    if (ensure_extra_volume
-        and not instance_type.startswith(tuple(INSTANCE_TYPES_WITH_STORAGE))):
+    if ensure_extra_volume and not instance_type.startswith(
+        tuple(INSTANCE_TYPES_WITH_STORAGE)
+    ):
         main_device = block_device_mappings[0]['DeviceName']
 
         if main_device == 'xvda':
@@ -987,17 +1004,20 b' def temporary_linux_dev_instances(c: AWS'
         elif main_device == '/dev/sda1':
             second_device = '/dev/sdb'
         else:
-            raise ValueError('unhandled primary EBS device name: %s' %
-                             main_device)
+            raise ValueError(
+                'unhandled primary EBS device name: %s' % main_device
+            )
 
-        block_device_mappings.append({
-            'DeviceName': second_device,
-            'Ebs': {
-                'DeleteOnTermination': True,
-                'VolumeSize': 8,
-                'VolumeType': 'gp2',
+        block_device_mappings.append(
+            {
+                'DeviceName': second_device,
+                'Ebs': {
+                    'DeleteOnTermination': True,
+                    'VolumeSize': 8,
+                    'VolumeType': 'gp2',
+                },
             }
-        })
+        )
 
     config = {
         'BlockDeviceMappings': block_device_mappings,
@@ -1018,9 +1038,11 b' def temporary_linux_dev_instances(c: AWS'
 
         for instance in instances:
             client = wait_for_ssh(
-                instance.public_ip_address, 22,
+                instance.public_ip_address,
+                22,
                 username='hg',
-                key_filename=ssh_private_key_path)
+                key_filename=ssh_private_key_path,
+            )
 
             instance.ssh_client = client
             instance.ssh_private_key_path = ssh_private_key_path
@@ -1032,8 +1054,9 b' def temporary_linux_dev_instances(c: AWS'
                 instance.ssh_client.close()
 
 
-def ensure_windows_dev_ami(c: AWSConnection, prefix='hg-',
-                           base_image_name=WINDOWS_BASE_IMAGE_NAME):
+def ensure_windows_dev_ami(
+    c: AWSConnection, prefix='hg-', base_image_name=WINDOWS_BASE_IMAGE_NAME
+):
     """Ensure Windows Development AMI is available and up-to-date.
 
     If necessary, a modern AMI will be built by starting a temporary EC2
@@ -1092,6 +1115,23 b' def ensure_windows_dev_ami(c: AWSConnect'
     with INSTALL_WINDOWS_DEPENDENCIES.open('r', encoding='utf-8') as fh:
         commands.extend(l.rstrip() for l in fh)
 
+    # Schedule run of EC2Launch on next boot. This ensures that UserData
+    # is executed.
+    # We disable setComputerName because it forces a reboot.
+    # We set an explicit admin password because this causes UserData to run
+    # as Administrator instead of System.
+    commands.extend(
+        [
+            r'''Set-Content -Path C:\ProgramData\Amazon\EC2-Windows\Launch\Config\LaunchConfig.json '''
+            r'''-Value '{"setComputerName": false, "setWallpaper": true, "addDnsSuffixList": true, '''
+            r'''"extendBootVolumeSize": true, "handleUserData": true, '''
+            r'''"adminPasswordType": "Specify", "adminPassword": "%s"}' '''
+            % c.automation.default_password(),
+            r'C:\ProgramData\Amazon\EC2-Windows\Launch\Scripts\InitializeInstance.ps1 '
+            r'–Schedule',
+        ]
+    )
+
     # Disable Windows Defender when bootstrapping because it just slows
     # things down.
     commands.insert(0, 'Set-MpPreference -DisableRealtimeMonitoring $true')
@@ -1099,13 +1139,15 b' def ensure_windows_dev_ami(c: AWSConnect'
 
     # Compute a deterministic fingerprint to determine whether image needs
     # to be regenerated.
-    fingerprint = resolve_fingerprint({
-        'instance_config': config,
-        'user_data': WINDOWS_USER_DATA,
-        'initial_bootstrap': WINDOWS_BOOTSTRAP_POWERSHELL,
-        'bootstrap_commands': commands,
-        'base_image_name': base_image_name,
-    })
+    fingerprint = resolve_fingerprint(
+        {
+            'instance_config': config,
+            'user_data': WINDOWS_USER_DATA,
+            'initial_bootstrap': WINDOWS_BOOTSTRAP_POWERSHELL,
+            'bootstrap_commands': commands,
+            'base_image_name': base_image_name,
+        }
+    )
 
     existing_image = find_and_reconcile_image(ec2resource, name, fingerprint)
 
@@ -1114,7 +1156,9 b' def ensure_windows_dev_ami(c: AWSConnect'
 
     print('no suitable Windows development image found; creating one...')
 
-    with create_temp_windows_ec2_instances(c, config) as instances:
+    with create_temp_windows_ec2_instances(
+        c, config, bootstrap=True
+    ) as instances:
         assert len(instances) == 1
         instance = instances[0]
 
@@ -1130,9 +1174,7 b' def ensure_windows_dev_ami(c: AWSConnect'
             ssmclient,
             [instance],
             'AWS-RunPowerShellScript',
-            {
-                'commands': WINDOWS_BOOTSTRAP_POWERSHELL.split('\n'),
-            },
+            {'commands': WINDOWS_BOOTSTRAP_POWERSHELL.split('\n'),},
         )
 
         # Reboot so all updates are fully applied.
@@ -1144,10 +1186,8 b' def ensure_windows_dev_ami(c: AWSConnect'
         print('rebooting instance %s' % instance.id)
         instance.stop()
         ec2client.get_waiter('instance_stopped').wait(
-            InstanceIds=[instance.id],
-            WaiterConfig={
-                'Delay': 5,
-            })
+            InstanceIds=[instance.id], WaiterConfig={'Delay': 5,}
+        )
 
         instance.start()
         wait_for_ip_addresses([instance])
@@ -1158,8 +1198,11 b' def ensure_windows_dev_ami(c: AWSConnect'
         # TODO figure out a workaround.
 
         print('waiting for Windows Remote Management to come back...')
-        client = wait_for_winrm(instance.public_ip_address, 'Administrator',
-                                c.automation.default_password())
+        client = wait_for_winrm(
+            instance.public_ip_address,
+            'Administrator',
+            c.automation.default_password(),
+        )
         print('established WinRM connection to %s' % instance.id)
         instance.winrm_client = client
 
@@ -1167,14 +1210,23 b' def ensure_windows_dev_ami(c: AWSConnect'
         run_powershell(instance.winrm_client, '\n'.join(commands))
 
         print('bootstrap completed; stopping %s to create image' % instance.id)
-        return create_ami_from_instance(ec2client, instance, name,
-                                        'Mercurial Windows development environment',
-                                        fingerprint)
+        return create_ami_from_instance(
+            ec2client,
+            instance,
+            name,
+            'Mercurial Windows development environment',
+            fingerprint,
+        )
 
 
 @contextlib.contextmanager
-def temporary_windows_dev_instances(c: AWSConnection, image, instance_type,
-                                    prefix='hg-', disable_antivirus=False):
+def temporary_windows_dev_instances(
+    c: AWSConnection,
+    image,
+    instance_type,
+    prefix='hg-',
+    disable_antivirus=False,
+):
     """Create a temporary Windows development EC2 instance.
 
     Context manager resolves to the list of ``EC2.Instance`` that were created.
@@ -1204,6 +1256,7 b' def temporary_windows_dev_instances(c: A'
             for instance in instances:
                 run_powershell(
                     instance.winrm_client,
-                    'Set-MpPreference -DisableRealtimeMonitoring $true')
+                    'Set-MpPreference -DisableRealtimeMonitoring $true',
+                )
 
         yield instances

contrib/automation/hgautomation/cli.py

@@ -17,16 +17,20 b' from . import ('
     aws,
     HGAutomation,
     linux,
+    try_server,
     windows,
 )
 
 
-SOURCE_ROOT = pathlib.Path(os.path.abspath(__file__)).parent.parent.parent.parent
+SOURCE_ROOT = pathlib.Path(
+    os.path.abspath(__file__)
+).parent.parent.parent.parent
 DIST_PATH = SOURCE_ROOT / 'dist'
 
 
-def bootstrap_linux_dev(hga: HGAutomation, aws_region, distros=None,
-                        parallel=False):
+def bootstrap_linux_dev(
+    hga: HGAutomation, aws_region, distros=None, parallel=False
+):
     c = hga.aws_connection(aws_region)
 
     if distros:
@@ -58,8 +62,9 b' def bootstrap_windows_dev(hga: HGAutomat'
     print('Windows development AMI available as %s' % image.id)
 
 
-def build_inno(hga: HGAutomation, aws_region, arch, revision, version,
-               base_image_name):
+def build_inno(
+    hga: HGAutomation, aws_region, arch, revision, version, base_image_name
+):
     c = hga.aws_connection(aws_region)
     image = aws.ensure_windows_dev_ami(c, base_image_name=base_image_name)
     DIST_PATH.mkdir(exist_ok=True)
@@ -70,13 +75,14 b' def build_inno(hga: HGAutomation, aws_re'
         windows.synchronize_hg(SOURCE_ROOT, revision, instance)
 
         for a in arch:
-            windows.build_inno_installer(instance.winrm_client, a,
-                                         DIST_PATH,
-                                         version=version)
+            windows.build_inno_installer(
+                instance.winrm_client, a, DIST_PATH, version=version
+            )
 
 
-def build_wix(hga: HGAutomation, aws_region, arch, revision, version,
-              base_image_name):
+def build_wix(
+    hga: HGAutomation, aws_region, arch, revision, version, base_image_name
+):
     c = hga.aws_connection(aws_region)
     image = aws.ensure_windows_dev_ami(c, base_image_name=base_image_name)
     DIST_PATH.mkdir(exist_ok=True)
@@ -87,12 +93,14 b' def build_wix(hga: HGAutomation, aws_reg'
         windows.synchronize_hg(SOURCE_ROOT, revision, instance)
 
         for a in arch:
-            windows.build_wix_installer(instance.winrm_client, a,
-                                        DIST_PATH, version=version)
+            windows.build_wix_installer(
+                instance.winrm_client, a, DIST_PATH, version=version
+            )
 
 
-def build_windows_wheel(hga: HGAutomation, aws_region, arch, revision,
-                        base_image_name):
+def build_windows_wheel(
+    hga: HGAutomation, aws_region, arch, revision, base_image_name
+):
     c = hga.aws_connection(aws_region)
     image = aws.ensure_windows_dev_ami(c, base_image_name=base_image_name)
     DIST_PATH.mkdir(exist_ok=True)
@@ -106,8 +114,9 b' def build_windows_wheel(hga: HGAutomatio'
             windows.build_wheel(instance.winrm_client, a, DIST_PATH)
 
 
-def build_all_windows_packages(hga: HGAutomation, aws_region, revision,
-                               version, base_image_name):
+def build_all_windows_packages(
+    hga: HGAutomation, aws_region, revision, version, base_image_name
+):
     c = hga.aws_connection(aws_region)
     image = aws.ensure_windows_dev_ami(c, base_image_name=base_image_name)
     DIST_PATH.mkdir(exist_ok=True)
@@ -123,11 +132,13 b' def build_all_windows_packages(hga: HGAu'
             windows.purge_hg(winrm_client)
             windows.build_wheel(winrm_client, arch, DIST_PATH)
             windows.purge_hg(winrm_client)
-            windows.build_inno_installer(winrm_client, arch, DIST_PATH,
-                                         version=version)
+            windows.build_inno_installer(
+                winrm_client, arch, DIST_PATH, version=version
+            )
             windows.purge_hg(winrm_client)
-            windows.build_wix_installer(winrm_client, arch, DIST_PATH,
-                                        version=version)
+            windows.build_wix_installer(
+                winrm_client, arch, DIST_PATH, version=version
+            )
 
 
 def terminate_ec2_instances(hga: HGAutomation, aws_region):
@@ -140,8 +151,15 b' def purge_ec2_resources(hga: HGAutomatio'
     aws.remove_resources(c)
 
 
-def run_tests_linux(hga: HGAutomation, aws_region, instance_type,
-                    python_version, test_flags, distro, filesystem):
+def run_tests_linux(
+    hga: HGAutomation,
+    aws_region,
+    instance_type,
+    python_version,
+    test_flags,
+    distro,
+    filesystem,
+):
     c = hga.aws_connection(aws_region)
     image = aws.ensure_linux_dev_ami(c, distro=distro)
 
@@ -150,17 +168,17 b' def run_tests_linux(hga: HGAutomation, a'
     ensure_extra_volume = filesystem not in ('default', 'tmpfs')
 
     with aws.temporary_linux_dev_instances(
-        c, image, instance_type,
-        ensure_extra_volume=ensure_extra_volume) as insts:
+        c, image, instance_type, ensure_extra_volume=ensure_extra_volume
+    ) as insts:
 
         instance = insts[0]
 
-        linux.prepare_exec_environment(instance.ssh_client,
-                                       filesystem=filesystem)
+        linux.prepare_exec_environment(
+            instance.ssh_client, filesystem=filesystem
+        )
         linux.synchronize_hg(SOURCE_ROOT, instance, '.')
         t_prepared = time.time()
-        linux.run_tests(instance.ssh_client, python_version,
-                        test_flags)
+        linux.run_tests(instance.ssh_client, python_version, test_flags)
         t_done = time.time()
 
     t_setup = t_prepared - t_start
@@ -168,21 +186,53 b' def run_tests_linux(hga: HGAutomation, a'
 
     print(
         'total time: %.1fs; setup: %.1fs; tests: %.1fs; setup overhead: %.1f%%'
-        % (t_all, t_setup, t_done - t_prepared, t_setup / t_all * 100.0))
+        % (t_all, t_setup, t_done - t_prepared, t_setup / t_all * 100.0)
+    )
 
 
-def run_tests_windows(hga: HGAutomation, aws_region, instance_type,
-                      python_version, arch, test_flags, base_image_name):
+def run_tests_windows(
+    hga: HGAutomation,
+    aws_region,
+    instance_type,
+    python_version,
+    arch,
+    test_flags,
+    base_image_name,
+):
     c = hga.aws_connection(aws_region)
     image = aws.ensure_windows_dev_ami(c, base_image_name=base_image_name)
 
-    with aws.temporary_windows_dev_instances(c, image, instance_type,
-                                             disable_antivirus=True) as insts:
+    with aws.temporary_windows_dev_instances(
+        c, image, instance_type, disable_antivirus=True
+    ) as insts:
         instance = insts[0]
 
         windows.synchronize_hg(SOURCE_ROOT, '.', instance)
-        windows.run_tests(instance.winrm_client, python_version, arch,
-                          test_flags)
+        windows.run_tests(
+            instance.winrm_client, python_version, arch, test_flags
+        )
+
+
+def publish_windows_artifacts(
+    hg: HGAutomation,
+    aws_region,
+    version: str,
+    pypi: bool,
+    mercurial_scm_org: bool,
+    ssh_username: str,
+):
+    windows.publish_artifacts(
+        DIST_PATH,
+        version,
+        pypi=pypi,
+        mercurial_scm_org=mercurial_scm_org,
+        ssh_username=ssh_username,
+    )
+
+
+def run_try(hga: HGAutomation, aws_region: str, rev: str):
+    c = hga.aws_connection(aws_region, ensure_ec2_state=False)
+    try_server.trigger_try(c, rev=rev)
 
 
 def get_parser():
@@ -194,25 +244,21 b' def get_parser():'
         help='Path for local state files',
     )
     parser.add_argument(
-        '--aws-region',
-        help='AWS region to use',
-        default='us-west-1',
+        '--aws-region', help='AWS region to use', default='us-west-2',
     )
 
     subparsers = parser.add_subparsers()
 
     sp = subparsers.add_parser(
-        'bootstrap-linux-dev',
-        help='Bootstrap Linux development environments',
+        'bootstrap-linux-dev', help='Bootstrap Linux development environments',
     )
     sp.add_argument(
-        '--distros',
-        help='Comma delimited list of distros to bootstrap',
+        '--distros', help='Comma delimited list of distros to bootstrap',
     )
     sp.add_argument(
         '--parallel',
         action='store_true',
-        help='Generate AMIs in parallel (not CTRL-c safe)'
+        help='Generate AMIs in parallel (not CTRL-c safe)',
     )
     sp.set_defaults(func=bootstrap_linux_dev)
 
@@ -228,17 +274,13 b' def get_parser():'
     sp.set_defaults(func=bootstrap_windows_dev)
 
     sp = subparsers.add_parser(
-        'build-all-windows-packages',
-        help='Build all Windows packages',
+        'build-all-windows-packages', help='Build all Windows packages',
     )
     sp.add_argument(
-        '--revision',
-        help='Mercurial revision to build',
-        default='.',
+        '--revision', help='Mercurial revision to build', default='.',
     )
     sp.add_argument(
-        '--version',
-        help='Mercurial version string to use',
+        '--version', help='Mercurial version string to use',
     )
     sp.add_argument(
         '--base-image-name',
@@ -248,8 +290,7 b' def get_parser():'
     sp.set_defaults(func=build_all_windows_packages)
 
     sp = subparsers.add_parser(
-        'build-inno',
-        help='Build Inno Setup installer(s)',
+        'build-inno', help='Build Inno Setup installer(s)',
     )
     sp.add_argument(
         '--arch',
@@ -259,13 +300,10 b' def get_parser():'
         default=['x64'],
     )
     sp.add_argument(
-        '--revision',
-        help='Mercurial revision to build',
-        default='.',
+        '--revision', help='Mercurial revision to build', default='.',
     )
     sp.add_argument(
-        '--version',
-        help='Mercurial version string to use in installer',
+        '--version', help='Mercurial version string to use in installer',
     )
     sp.add_argument(
         '--base-image-name',
@@ -275,8 +313,7 b' def get_parser():'
     sp.set_defaults(func=build_inno)
 
     sp = subparsers.add_parser(
-        'build-windows-wheel',
-        help='Build Windows wheel(s)',
+        'build-windows-wheel', help='Build Windows wheel(s)',
     )
     sp.add_argument(
         '--arch',
@@ -286,9 +323,7 b' def get_parser():'
         default=['x64'],
     )
     sp.add_argument(
-        '--revision',
-        help='Mercurial revision to build',
-        default='.',
+        '--revision', help='Mercurial revision to build', default='.',
     )
     sp.add_argument(
         '--base-image-name',
@@ -297,10 +332,7 b' def get_parser():'
     )
     sp.set_defaults(func=build_windows_wheel)
 
-    sp = subparsers.add_parser(
-        'build-wix',
-        help='Build WiX installer(s)'
-    )
+    sp = subparsers.add_parser('build-wix', help='Build WiX installer(s)')
     sp.add_argument(
         '--arch',
         help='Architecture to build for',
@@ -309,13 +341,10 b' def get_parser():'
         default=['x64'],
     )
     sp.add_argument(
-        '--revision',
-        help='Mercurial revision to build',
-        default='.',
+        '--revision', help='Mercurial revision to build', default='.',
     )
     sp.add_argument(
-        '--version',
-        help='Mercurial version string to use in installer',
+        '--version', help='Mercurial version string to use in installer',
     )
     sp.add_argument(
         '--base-image-name',
@@ -331,20 +360,16 b' def get_parser():'
     sp.set_defaults(func=terminate_ec2_instances)
 
     sp = subparsers.add_parser(
-        'purge-ec2-resources',
-        help='Purge all EC2 resources managed by us',
+        'purge-ec2-resources', help='Purge all EC2 resources managed by us',
     )
     sp.set_defaults(func=purge_ec2_resources)
 
-    sp = subparsers.add_parser(
-        'run-tests-linux',
-        help='Run tests on Linux',
-    )
+    sp = subparsers.add_parser('run-tests-linux', help='Run tests on Linux',)
     sp.add_argument(
         '--distro',
         help='Linux distribution to run tests on',
         choices=linux.DISTROS,
-        default='debian9',
+        default='debian10',
     )
     sp.add_argument(
         '--filesystem',
@@ -360,8 +385,18 b' def get_parser():'
     sp.add_argument(
         '--python-version',
         help='Python version to use',
-        choices={'system2', 'system3', '2.7', '3.5', '3.6', '3.7', '3.8',
-                 'pypy', 'pypy3.5', 'pypy3.6'},
+        choices={
+            'system2',
+            'system3',
+            '2.7',
+            '3.5',
+            '3.6',
+            '3.7',
+            '3.8',
+            'pypy',
+            'pypy3.5',
+            'pypy3.6',
+        },
         default='system2',
     )
     sp.add_argument(
@@ -372,13 +407,10 b' def get_parser():'
     sp.set_defaults(func=run_tests_linux)
 
     sp = subparsers.add_parser(
-        'run-tests-windows',
-        help='Run tests on Windows',
+        'run-tests-windows', help='Run tests on Windows',
     )
     sp.add_argument(
-        '--instance-type',
-        help='EC2 instance type to use',
-        default='t3.medium',
+        '--instance-type', help='EC2 instance type to use', default='t3.medium',
     )
     sp.add_argument(
         '--python-version',
@@ -393,8 +425,7 b' def get_parser():'
         default='x64',
     )
     sp.add_argument(
-        '--test-flags',
-        help='Extra command line flags to pass to run-tests.py',
+        '--test-flags', help='Extra command line flags to pass to run-tests.py',
     )
     sp.add_argument(
         '--base-image-name',
@@ -403,6 +434,38 b' def get_parser():'
     )
     sp.set_defaults(func=run_tests_windows)
 
+    sp = subparsers.add_parser(
+        'publish-windows-artifacts',
+        help='Publish built Windows artifacts (wheels, installers, etc)',
+    )
+    sp.add_argument(
+        '--no-pypi',
+        dest='pypi',
+        action='store_false',
+        default=True,
+        help='Skip uploading to PyPI',
+    )
+    sp.add_argument(
+        '--no-mercurial-scm-org',
+        dest='mercurial_scm_org',
+        action='store_false',
+        default=True,
+        help='Skip uploading to www.mercurial-scm.org',
+    )
+    sp.add_argument(
+        '--ssh-username', help='SSH username for mercurial-scm.org',
+    )
+    sp.add_argument(
+        'version', help='Mercurial version string to locate local packages',
+    )
+    sp.set_defaults(func=publish_windows_artifacts)
+
+    sp = subparsers.add_parser(
+        'try', help='Run CI automation against a custom changeset'
+    )
+    sp.add_argument('-r', '--rev', default='.', help='Revision to run CI on')
+    sp.set_defaults(func=run_try)
+
     return parser
 
 

contrib/automation/hgautomation/linux.py

@@ -13,39 +13,37 b' import shlex'
 import subprocess
 import tempfile
 
-from .ssh import (
-    exec_command,
-)
+from .ssh import exec_command
 
 
 # Linux distributions that are supported.
 DISTROS = {
     'debian9',
+    'debian10',
     'ubuntu18.04',
-    'ubuntu18.10',
     'ubuntu19.04',
 }
 
 INSTALL_PYTHONS = r'''
 PYENV2_VERSIONS="2.7.16 pypy2.7-7.1.1"
-PYENV3_VERSIONS="3.5.7 3.6.8 3.7.3 3.8-dev pypy3.5-7.0.0 pypy3.6-7.1.1"
+PYENV3_VERSIONS="3.5.7 3.6.9 3.7.4 3.8.0 pypy3.5-7.0.0 pypy3.6-7.1.1"
 
 git clone https://github.com/pyenv/pyenv.git /hgdev/pyenv
 pushd /hgdev/pyenv
-git checkout 3faeda67bb33e07750d1a104271369a7384ca45c
+git checkout d6d6bc8bb08bcdcbf4eb79509aa7061011ade1c4
 popd
 
 export PYENV_ROOT="/hgdev/pyenv"
 export PATH="$PYENV_ROOT/bin:$PATH"
 
-# pip 19.0.3.
-PIP_SHA256=efe99298f3fbb1f56201ce6b81d2658067d2f7d7dfc2d412e0d3cacc9a397c61
-wget -O get-pip.py --progress dot:mega https://github.com/pypa/get-pip/raw/fee32c376da1ff6496a798986d7939cd51e1644f/get-pip.py
+# pip 19.2.3.
+PIP_SHA256=57e3643ff19f018f8a00dfaa6b7e4620e3c1a7a2171fd218425366ec006b3bfe
+wget -O get-pip.py --progress dot:mega https://github.com/pypa/get-pip/raw/309a56c5fd94bd1134053a541cb4657a4e47e09d/get-pip.py
 echo "${PIP_SHA256} get-pip.py" | sha256sum --check -
 
-VIRTUALENV_SHA256=984d7e607b0a5d1329425dd8845bd971b957424b5ba664729fab51ab8c11bc39
-VIRTUALENV_TARBALL=virtualenv-16.4.3.tar.gz
-wget -O ${VIRTUALENV_TARBALL} --progress dot:mega https://files.pythonhosted.org/packages/37/db/89d6b043b22052109da35416abc3c397655e4bd3cff031446ba02b9654fa/${VIRTUALENV_TARBALL}
+VIRTUALENV_SHA256=f78d81b62d3147396ac33fc9d77579ddc42cc2a98dd9ea38886f616b33bc7fb2
+VIRTUALENV_TARBALL=virtualenv-16.7.5.tar.gz
+wget -O ${VIRTUALENV_TARBALL} --progress dot:mega https://files.pythonhosted.org/packages/66/f0/6867af06d2e2f511e4e1d7094ff663acdebc4f15d4a0cb0fed1007395124/${VIRTUALENV_TARBALL}
 echo "${VIRTUALENV_SHA256} ${VIRTUALENV_TARBALL}" | sha256sum --check -
 
 for v in ${PYENV2_VERSIONS}; do
@@ -62,23 +60,40 b' for v in ${PYENV3_VERSIONS}; do'
 done
 
 pyenv global ${PYENV2_VERSIONS} ${PYENV3_VERSIONS} system
-'''.lstrip().replace('\r\n', '\n')
+'''.lstrip().replace(
+    '\r\n', '\n'
+)
+
+
+INSTALL_RUST = r'''
+RUSTUP_INIT_SHA256=a46fe67199b7bcbbde2dcbc23ae08db6f29883e260e23899a88b9073effc9076
+wget -O rustup-init --progress dot:mega https://static.rust-lang.org/rustup/archive/1.18.3/x86_64-unknown-linux-gnu/rustup-init
+echo "${RUSTUP_INIT_SHA256} rustup-init" | sha256sum --check -
+
+chmod +x rustup-init
+sudo -H -u hg -g hg ./rustup-init -y
+sudo -H -u hg -g hg /home/hg/.cargo/bin/rustup install 1.31.1 1.34.2
+sudo -H -u hg -g hg /home/hg/.cargo/bin/rustup component add clippy
+'''
 
 
 BOOTSTRAP_VIRTUALENV = r'''
 /usr/bin/virtualenv /hgdev/venv-bootstrap
 
-HG_SHA256=1bdd21bb87d1e05fb5cd395d488d0e0cc2f2f90ce0fd248e31a03595da5ccb47
-HG_TARBALL=mercurial-4.9.1.tar.gz
+HG_SHA256=35fc8ba5e0379c1b3affa2757e83fb0509e8ac314cbd9f1fd133cf265d16e49f
+HG_TARBALL=mercurial-5.1.1.tar.gz
 
 wget -O ${HG_TARBALL} --progress dot:mega https://www.mercurial-scm.org/release/${HG_TARBALL}
 echo "${HG_SHA256} ${HG_TARBALL}" | sha256sum --check -
 
 /hgdev/venv-bootstrap/bin/pip install ${HG_TARBALL}
-'''.lstrip().replace('\r\n', '\n')
+'''.lstrip().replace(
+    '\r\n', '\n'
+)
 
 
-BOOTSTRAP_DEBIAN = r'''
+BOOTSTRAP_DEBIAN = (
+    r'''
 #!/bin/bash
 
 set -ex
@@ -175,18 +190,22 b' EOF'
 
 sudo apt-key add docker-apt-key
 
-if [ "$DEBIAN_VERSION" = "9.8" ]; then
+if [ "$LSB_RELEASE" = "stretch" ]; then
 cat << EOF | sudo tee -a /etc/apt/sources.list
 # Need backports for clang-format-6.0
 deb http://deb.debian.org/debian stretch-backports main
+EOF
+fi
 
+if [ "$LSB_RELEASE" = "stretch" -o "$LSB_RELEASE" = "buster" ]; then
+cat << EOF | sudo tee -a /etc/apt/sources.list
 # Sources are useful if we want to compile things locally.
-deb-src http://deb.debian.org/debian stretch main
-deb-src http://security.debian.org/debian-security stretch/updates main
-deb-src http://deb.debian.org/debian stretch-updates main
-deb-src http://deb.debian.org/debian stretch-backports main
+deb-src http://deb.debian.org/debian $LSB_RELEASE main
+deb-src http://security.debian.org/debian-security $LSB_RELEASE/updates main
+deb-src http://deb.debian.org/debian $LSB_RELEASE-updates main
+deb-src http://deb.debian.org/debian $LSB_RELEASE-backports main
 
-deb [arch=amd64] https://download.docker.com/linux/debian stretch stable
+deb [arch=amd64] https://download.docker.com/linux/debian $LSB_RELEASE stable
 EOF
 
 elif [ "$DISTRO" = "Ubuntu" ]; then
@@ -199,6 +218,7 b' fi'
 sudo apt-get update
 
 PACKAGES="\
+    awscli \
     btrfs-progs \
     build-essential \
     bzr \
@@ -207,6 +227,7 b' PACKAGES="\\'
     darcs \
     debhelper \
     devscripts \
+    docker-ce \
     dpkg-dev \
     dstat \
     emacs \
@@ -239,6 +260,7 b' PACKAGES="\\'
     python-pygments \
     python-subversion \
     python-vcr \
+    python3-boto3 \
     python3-dev \
     python3-docutils \
     python3-fuzzywuzzy \
@@ -259,23 +281,17 b' PACKAGES="\\'
     zip \
     zlib1g-dev"
 
-if [ "$DEBIAN_VERSION" = "9.8" ]; then
+if [ "LSB_RELEASE" = "stretch" ]; then
     PACKAGES="$PACKAGES linux-perf"
 elif [ "$DISTRO" = "Ubuntu" ]; then
     PACKAGES="$PACKAGES linux-tools-common"
 fi
 
-# Ubuntu 19.04 removes monotone.
-if [ "$LSB_RELEASE" != "disco" ]; then
+# Monotone only available in older releases.
+if [ "$LSB_RELEASE" = "stretch" -o "$LSB_RELEASE" = "xenial" ]; then
     PACKAGES="$PACKAGES monotone"
 fi
 
-# As of April 27, 2019, Docker hasn't published packages for
-# Ubuntu 19.04 yet.
-if [ "$LSB_RELEASE" != "disco" ]; then
-    PACKAGES="$PACKAGES docker-ce"
-fi
-
 sudo DEBIAN_FRONTEND=noninteractive apt-get -yq install --no-install-recommends $PACKAGES
 
 # Create clang-format symlink so test harness finds it.
@@ -286,6 +302,8 b' sudo mkdir /hgdev'
 # Will be normalized to hg:hg later.
 sudo chown `whoami` /hgdev
 
+{install_rust}
+
 cp requirements-py2.txt /hgdev/requirements-py2.txt
 cp requirements-py3.txt /hgdev/requirements-py3.txt
 
@@ -308,10 +326,14 b' publish = false'
 EOF
 
 sudo chown -R hg:hg /hgdev
-'''.lstrip().format(
-    install_pythons=INSTALL_PYTHONS,
-    bootstrap_virtualenv=BOOTSTRAP_VIRTUALENV
-).replace('\r\n', '\n')
+'''.lstrip()
+    .format(
+        install_rust=INSTALL_RUST,
+        install_pythons=INSTALL_PYTHONS,
+        bootstrap_virtualenv=BOOTSTRAP_VIRTUALENV,
+    )
+    .replace('\r\n', '\n')
+)
 
 
 # Prepares /hgdev for operations.
@@ -393,7 +415,9 b' mkdir /hgwork/tmp'
 chown hg:hg /hgwork/tmp
 
 rsync -a /hgdev/src /hgwork/
-'''.lstrip().replace('\r\n', '\n')
+'''.lstrip().replace(
+    '\r\n', '\n'
+)
 
 
 HG_UPDATE_CLEAN = '''
@@ -405,7 +429,9 b' cd /hgwork/src'
 ${HG} --config extensions.purge= purge --all
 ${HG} update -C $1
 ${HG} log -r .
-'''.lstrip().replace('\r\n', '\n')
+'''.lstrip().replace(
+    '\r\n', '\n'
+)
 
 
 def prepare_exec_environment(ssh_client, filesystem='default'):
@@ -440,11 +466,12 b' def prepare_exec_environment(ssh_client,'
     res = chan.recv_exit_status()
 
     if res:
-        raise Exception('non-0 exit code updating working directory; %d'
-                        % res)
+        raise Exception('non-0 exit code updating working directory; %d' % res)
 
 
-def synchronize_hg(source_path: pathlib.Path, ec2_instance, revision: str=None):
+def synchronize_hg(
+    source_path: pathlib.Path, ec2_instance, revision: str = None
+):
     """Synchronize a local Mercurial source path to remote EC2 instance."""
 
     with tempfile.TemporaryDirectory() as temp_dir:
@@ -466,8 +493,10 b' def synchronize_hg(source_path: pathlib.'
             fh.write('  IdentityFile %s\n' % ec2_instance.ssh_private_key_path)
 
         if not (source_path / '.hg').is_dir():
-            raise Exception('%s is not a Mercurial repository; synchronization '
-                            'not yet supported' % source_path)
+            raise Exception(
+                '%s is not a Mercurial repository; synchronization '
+                'not yet supported' % source_path
+            )
 
         env = dict(os.environ)
         env['HGPLAIN'] = '1'
@@ -477,17 +506,29 b' def synchronize_hg(source_path: pathlib.'
 
         res = subprocess.run(
             ['python2.7', str(hg_bin), 'log', '-r', revision, '-T', '{node}'],
-            cwd=str(source_path), env=env, check=True, capture_output=True)
+            cwd=str(source_path),
+            env=env,
+            check=True,
+            capture_output=True,
+        )
 
         full_revision = res.stdout.decode('ascii')
 
         args = [
-            'python2.7', str(hg_bin),
-            '--config', 'ui.ssh=ssh -F %s' % ssh_config,
-            '--config', 'ui.remotecmd=/hgdev/venv-bootstrap/bin/hg',
+            'python2.7',
+            str(hg_bin),
+            '--config',
+            'ui.ssh=ssh -F %s' % ssh_config,
+            '--config',
+            'ui.remotecmd=/hgdev/venv-bootstrap/bin/hg',
             # Also ensure .hgtags changes are present so auto version
             # calculation works.
-            'push', '-f', '-r', full_revision, '-r', 'file(.hgtags)',
+            'push',
+            '-f',
+            '-r',
+            full_revision,
+            '-r',
+            'file(.hgtags)',
             'ssh://%s//hgwork/src' % public_ip,
         ]
 
@@ -506,7 +547,8 b' def synchronize_hg(source_path: pathlib.'
             fh.chmod(0o0700)
 
         chan, stdin, stdout = exec_command(
-            ec2_instance.ssh_client, '/hgdev/hgup %s' % full_revision)
+            ec2_instance.ssh_client, '/hgdev/hgup %s' % full_revision
+        )
         stdin.close()
 
         for line in stdout:
@@ -515,8 +557,9 b' def synchronize_hg(source_path: pathlib.'
         res = chan.recv_exit_status()
 
         if res:
-            raise Exception('non-0 exit code updating working directory; %d'
-                            % res)
+            raise Exception(
+                'non-0 exit code updating working directory; %d' % res
+            )
 
 
 def run_tests(ssh_client, python_version, test_flags=None):
@@ -538,8 +581,8 b' def run_tests(ssh_client, python_version'
 
     command = (
         '/bin/sh -c "export TMPDIR=/hgwork/tmp; '
-        'cd /hgwork/src/tests && %s run-tests.py %s"' % (
-            python, test_flags))
+        'cd /hgwork/src/tests && %s run-tests.py %s"' % (python, test_flags)
+    )
 
     chan, stdin, stdout = exec_command(ssh_client, command)
 

contrib/automation/hgautomation/ssh.py

@@ -11,14 +11,13 b' import socket'
 import time
 import warnings
 
-from cryptography.utils import (
-    CryptographyDeprecationWarning,
-)
+from cryptography.utils import CryptographyDeprecationWarning
 import paramiko
 
 
 def wait_for_ssh(hostname, port, timeout=60, username=None, key_filename=None):
     """Wait for an SSH server to start on the specified host and port."""
+
     class IgnoreHostKeyPolicy(paramiko.MissingHostKeyPolicy):
         def missing_host_key(self, client, hostname, key):
             return
@@ -28,17 +27,23 b' def wait_for_ssh(hostname, port, timeout'
     # paramiko triggers a CryptographyDeprecationWarning in the cryptography
     # package. Let's suppress
     with warnings.catch_warnings():
-        warnings.filterwarnings('ignore',
-                                category=CryptographyDeprecationWarning)
+        warnings.filterwarnings(
+            'ignore', category=CryptographyDeprecationWarning
+        )
 
         while True:
             client = paramiko.SSHClient()
             client.set_missing_host_key_policy(IgnoreHostKeyPolicy())
             try:
-                client.connect(hostname, port=port, username=username,
-                               key_filename=key_filename,
-                               timeout=5.0, allow_agent=False,
-                               look_for_keys=False)
+                client.connect(
+                    hostname,
+                    port=port,
+                    username=username,
+                    key_filename=key_filename,
+                    timeout=5.0,
+                    allow_agent=False,
+                    look_for_keys=False,
+                )
 
                 return client
             except socket.error:

contrib/automation/hgautomation/windows.py

@@ -7,15 +7,16 b''
 
 # no-check-code because Python 3 native.
 
+import datetime
 import os
+import paramiko
 import pathlib
 import re
 import subprocess
 import tempfile
 
-from .winrm import (
-    run_powershell,
-)
+from .pypi import upload as pypi_upload
+from .winrm import run_powershell
 
 
 # PowerShell commands to activate a Visual Studio 2008 environment.
@@ -100,6 +101,33 b' if ($LASTEXITCODE -ne 0) {{'
 }}
 '''
 
+X86_WHEEL_FILENAME = 'mercurial-{version}-cp27-cp27m-win32.whl'
+X64_WHEEL_FILENAME = 'mercurial-{version}-cp27-cp27m-win_amd64.whl'
+X86_EXE_FILENAME = 'Mercurial-{version}.exe'
+X64_EXE_FILENAME = 'Mercurial-{version}-x64.exe'
+X86_MSI_FILENAME = 'mercurial-{version}-x86.msi'
+X64_MSI_FILENAME = 'mercurial-{version}-x64.msi'
+
+MERCURIAL_SCM_BASE_URL = 'https://mercurial-scm.org/release/windows'
+
+X86_USER_AGENT_PATTERN = '.*Windows.*'
+X64_USER_AGENT_PATTERN = '.*Windows.*(WOW|x)64.*'
+
+X86_EXE_DESCRIPTION = (
+    'Mercurial {version} Inno Setup installer - x86 Windows '
+    '- does not require admin rights'
+)
+X64_EXE_DESCRIPTION = (
+    'Mercurial {version} Inno Setup installer - x64 Windows '
+    '- does not require admin rights'
+)
+X86_MSI_DESCRIPTION = (
+    'Mercurial {version} MSI installer - x86 Windows ' '- requires admin rights'
+)
+X64_MSI_DESCRIPTION = (
+    'Mercurial {version} MSI installer - x64 Windows ' '- requires admin rights'
+)
+
 
 def get_vc_prefix(arch):
     if arch == 'x86':
@@ -133,10 +161,21 b' def synchronize_hg(hg_repo: pathlib.Path'
         ssh_dir.chmod(0o0700)
 
         # Generate SSH key to use for communication.
-        subprocess.run([
-            'ssh-keygen', '-t', 'rsa', '-b', '4096', '-N', '',
-            '-f', str(ssh_dir / 'id_rsa')],
-            check=True, capture_output=True)
+        subprocess.run(
+            [
+                'ssh-keygen',
+                '-t',
+                'rsa',
+                '-b',
+                '4096',
+                '-N',
+                '',
+                '-f',
+                str(ssh_dir / 'id_rsa'),
+            ],
+            check=True,
+            capture_output=True,
+        )
 
         # Add it to ~/.ssh/authorized_keys on remote.
         # This assumes the file doesn't already exist.
@@ -157,8 +196,10 b' def synchronize_hg(hg_repo: pathlib.Path'
             fh.write('  IdentityFile %s\n' % (ssh_dir / 'id_rsa'))
 
         if not (hg_repo / '.hg').is_dir():
-            raise Exception('%s is not a Mercurial repository; '
-                            'synchronization not yet supported' % hg_repo)
+            raise Exception(
+                '%s is not a Mercurial repository; '
+                'synchronization not yet supported' % hg_repo
+            )
 
         env = dict(os.environ)
         env['HGPLAIN'] = '1'
@@ -168,17 +209,29 b' def synchronize_hg(hg_repo: pathlib.Path'
 
         res = subprocess.run(
             ['python2.7', str(hg_bin), 'log', '-r', revision, '-T', '{node}'],
-            cwd=str(hg_repo), env=env, check=True, capture_output=True)
+            cwd=str(hg_repo),
+            env=env,
+            check=True,
+            capture_output=True,
+        )
 
         full_revision = res.stdout.decode('ascii')
 
         args = [
-            'python2.7', hg_bin,
-            '--config', 'ui.ssh=ssh -F %s' % ssh_config,
-            '--config', 'ui.remotecmd=c:/hgdev/venv-bootstrap/Scripts/hg.exe',
+            'python2.7',
+            hg_bin,
+            '--config',
+            'ui.ssh=ssh -F %s' % ssh_config,
+            '--config',
+            'ui.remotecmd=c:/hgdev/venv-bootstrap/Scripts/hg.exe',
             # Also ensure .hgtags changes are present so auto version
             # calculation works.
-            'push', '-f', '-r', full_revision, '-r', 'file(.hgtags)',
+            'push',
+            '-f',
+            '-r',
+            full_revision,
+            '-r',
+            'file(.hgtags)',
             'ssh://%s/c:/hgdev/src' % public_ip,
         ]
 
@@ -188,8 +241,9 b' def synchronize_hg(hg_repo: pathlib.Path'
         if res.returncode not in (0, 1):
             res.check_returncode()
 
-        run_powershell(winrm_client,
-                       HG_UPDATE_CLEAN.format(revision=full_revision))
+        run_powershell(
+            winrm_client, HG_UPDATE_CLEAN.format(revision=full_revision)
+        )
 
         # TODO detect dirty local working directory and synchronize accordingly.
 
@@ -225,8 +279,9 b' def copy_latest_dist(winrm_client, patte'
     winrm_client.fetch(source, str(dest))
 
 
-def build_inno_installer(winrm_client, arch: str, dest_path: pathlib.Path,
-                         version=None):
+def build_inno_installer(
+    winrm_client, arch: str, dest_path: pathlib.Path, version=None
+):
     """Build the Inno Setup installer on a remote machine.
 
     Using a WinRM client, remote commands are executed to build
@@ -238,8 +293,9 b' def build_inno_installer(winrm_client, a'
     if version:
         extra_args.extend(['--version', version])
 
-    ps = get_vc_prefix(arch) + BUILD_INNO.format(arch=arch,
-                                                 extra_args=' '.join(extra_args))
+    ps = get_vc_prefix(arch) + BUILD_INNO.format(
+        arch=arch, extra_args=' '.join(extra_args)
+    )
     run_powershell(winrm_client, ps)
     copy_latest_dist(winrm_client, '*.exe', dest_path)
 
@@ -256,8 +312,9 b' def build_wheel(winrm_client, arch: str,'
     copy_latest_dist(winrm_client, '*.whl', dest_path)
 
 
-def build_wix_installer(winrm_client, arch: str, dest_path: pathlib.Path,
-                        version=None):
+def build_wix_installer(
+    winrm_client, arch: str, dest_path: pathlib.Path, version=None
+):
     """Build the WiX installer on a remote machine.
 
     Using a WinRM client, remote commands are executed to build a WiX installer.
@@ -267,8 +324,9 b' def build_wix_installer(winrm_client, ar'
     if version:
         extra_args.extend(['--version', version])
 
-    ps = get_vc_prefix(arch) + BUILD_WIX.format(arch=arch,
-                                                extra_args=' '.join(extra_args))
+    ps = get_vc_prefix(arch) + BUILD_WIX.format(
+        arch=arch, extra_args=' '.join(extra_args)
+    )
     run_powershell(winrm_client, ps)
     copy_latest_dist(winrm_client, '*.msi', dest_path)
 
@@ -282,17 +340,171 b' def run_tests(winrm_client, python_versi'
     ``run-tests.py``.
     """
     if not re.match(r'\d\.\d', python_version):
-        raise ValueError(r'python_version must be \d.\d; got %s' %
-                         python_version)
+        raise ValueError(
+            r'python_version must be \d.\d; got %s' % python_version
+        )
 
     if arch not in ('x86', 'x64'):
         raise ValueError('arch must be x86 or x64; got %s' % arch)
 
     python_path = 'python%s-%s' % (python_version.replace('.', ''), arch)
 
-    ps = RUN_TESTS.format(
-        python_path=python_path,
-        test_flags=test_flags or '',
+    ps = RUN_TESTS.format(python_path=python_path, test_flags=test_flags or '',)
+
+    run_powershell(winrm_client, ps)
+
+
+def resolve_wheel_artifacts(dist_path: pathlib.Path, version: str):
+    return (
+        dist_path / X86_WHEEL_FILENAME.format(version=version),
+        dist_path / X64_WHEEL_FILENAME.format(version=version),
+    )
+
+
+def resolve_all_artifacts(dist_path: pathlib.Path, version: str):
+    return (
+        dist_path / X86_WHEEL_FILENAME.format(version=version),
+        dist_path / X64_WHEEL_FILENAME.format(version=version),
+        dist_path / X86_EXE_FILENAME.format(version=version),
+        dist_path / X64_EXE_FILENAME.format(version=version),
+        dist_path / X86_MSI_FILENAME.format(version=version),
+        dist_path / X64_MSI_FILENAME.format(version=version),
+    )
+
+
+def generate_latest_dat(version: str):
+    x86_exe_filename = X86_EXE_FILENAME.format(version=version)
+    x64_exe_filename = X64_EXE_FILENAME.format(version=version)
+    x86_msi_filename = X86_MSI_FILENAME.format(version=version)
+    x64_msi_filename = X64_MSI_FILENAME.format(version=version)
+
+    entries = (
+        (
+            '10',
+            version,
+            X86_USER_AGENT_PATTERN,
+            '%s/%s' % (MERCURIAL_SCM_BASE_URL, x86_exe_filename),
+            X86_EXE_DESCRIPTION.format(version=version),
+        ),
+        (
+            '10',
+            version,
+            X64_USER_AGENT_PATTERN,
+            '%s/%s' % (MERCURIAL_SCM_BASE_URL, x64_exe_filename),
+            X64_EXE_DESCRIPTION.format(version=version),
+        ),
+        (
+            '10',
+            version,
+            X86_USER_AGENT_PATTERN,
+            '%s/%s' % (MERCURIAL_SCM_BASE_URL, x86_msi_filename),
+            X86_MSI_DESCRIPTION.format(version=version),
+        ),
+        (
+            '10',
+            version,
+            X64_USER_AGENT_PATTERN,
+            '%s/%s' % (MERCURIAL_SCM_BASE_URL, x64_msi_filename),
+            X64_MSI_DESCRIPTION.format(version=version),
+        ),
     )
 
-    run_powershell(winrm_client, ps)
+    lines = ['\t'.join(e) for e in entries]
+
+    return '\n'.join(lines) + '\n'
+
+
+def publish_artifacts_pypi(dist_path: pathlib.Path, version: str):
+    """Publish Windows release artifacts to PyPI."""
+
+    wheel_paths = resolve_wheel_artifacts(dist_path, version)
+
+    for p in wheel_paths:
+        if not p.exists():
+            raise Exception('%s not found' % p)
+
+    print('uploading wheels to PyPI (you may be prompted for credentials)')
+    pypi_upload(wheel_paths)
+
+
+def publish_artifacts_mercurial_scm_org(
+    dist_path: pathlib.Path, version: str, ssh_username=None
+):
+    """Publish Windows release artifacts to mercurial-scm.org."""
+    all_paths = resolve_all_artifacts(dist_path, version)
+
+    for p in all_paths:
+        if not p.exists():
+            raise Exception('%s not found' % p)
+
+    client = paramiko.SSHClient()
+    client.load_system_host_keys()
+    # We assume the system SSH configuration knows how to connect.
+    print('connecting to mercurial-scm.org via ssh...')
+    try:
+        client.connect('mercurial-scm.org', username=ssh_username)
+    except paramiko.AuthenticationException:
+        print('error authenticating; is an SSH key available in an SSH agent?')
+        raise
+
+    print('SSH connection established')
+
+    print('opening SFTP client...')
+    sftp = client.open_sftp()
+    print('SFTP client obtained')
+
+    for p in all_paths:
+        dest_path = '/var/www/release/windows/%s' % p.name
+        print('uploading %s to %s' % (p, dest_path))
+
+        with p.open('rb') as fh:
+            data = fh.read()
+
+        with sftp.open(dest_path, 'wb') as fh:
+            fh.write(data)
+            fh.chmod(0o0664)
+
+    latest_dat_path = '/var/www/release/windows/latest.dat'
+
+    now = datetime.datetime.utcnow()
+    backup_path = dist_path / (
+        'latest-windows-%s.dat' % now.strftime('%Y%m%dT%H%M%S')
+    )
+    print('backing up %s to %s' % (latest_dat_path, backup_path))
+
+    with sftp.open(latest_dat_path, 'rb') as fh:
+        latest_dat_old = fh.read()
+
+    with backup_path.open('wb') as fh:
+        fh.write(latest_dat_old)
+
+    print('writing %s with content:' % latest_dat_path)
+    latest_dat_content = generate_latest_dat(version)
+    print(latest_dat_content)
+
+    with sftp.open(latest_dat_path, 'wb') as fh:
+        fh.write(latest_dat_content.encode('ascii'))
+
+
+def publish_artifacts(
+    dist_path: pathlib.Path,
+    version: str,
+    pypi=True,
+    mercurial_scm_org=True,
+    ssh_username=None,
+):
+    """Publish Windows release artifacts.
+
+    Files are found in `dist_path`. We will look for files with version string
+    `version`.
+
+    `pypi` controls whether we upload to PyPI.
+    `mercurial_scm_org` controls whether we upload to mercurial-scm.org.
+    """
+    if pypi:
+        publish_artifacts_pypi(dist_path, version)
+
+    if mercurial_scm_org:
+        publish_artifacts_mercurial_scm_org(
+            dist_path, version, ssh_username=ssh_username
+        )

contrib/automation/hgautomation/winrm.py

@@ -11,9 +11,7 b' import logging'
 import pprint
 import time
 
-from pypsrp.client import (
-    Client,
-)
+from pypsrp.client import Client
 from pypsrp.powershell import (
     PowerShell,
     PSInvocationState,
@@ -35,8 +33,13 b' def wait_for_winrm(host, username, passw'
 
     while True:
         try:
-            client = Client(host, username=username, password=password,
-                            ssl=ssl, connection_timeout=5)
+            client = Client(
+                host,
+                username=username,
+                password=password,
+                ssl=ssl,
+                connection_timeout=5,
+            )
             client.execute_ps("Write-Host 'Hello, World!'")
             return client
         except requests.exceptions.ConnectionError:
@@ -52,7 +55,7 b' def format_object(o):'
 
     try:
         o = str(o)
-    except TypeError:
+    except (AttributeError, TypeError):
         o = pprint.pformat(o.extended_properties)
 
     return o
@@ -78,5 +81,7 b' def run_powershell(client, script):'
             print(format_object(o))
 
         if ps.state == PSInvocationState.FAILED:
-            raise Exception('PowerShell execution failed: %s' %
-                            ' '.join(map(format_object, ps.streams.error)))
+            raise Exception(
+                'PowerShell execution failed: %s'
+                % ' '.join(map(format_object, ps.streams.error))
+            )

contrib/automation/linux-requirements-py2.txt

@@ -2,7 +2,7 b''
 # This file is autogenerated by pip-compile
 # To update, run:
 #
-#    pip-compile -U --generate-hashes --output-file contrib/automation/linux-requirements-py2.txt contrib/automation/linux-requirements.txt.in
+#    pip-compile --generate-hashes --output-file=contrib/automation/linux-requirements-py2.txt contrib/automation/linux-requirements.txt.in
 #
 astroid==1.6.6 \
     --hash=sha256:87de48a92e29cedf7210ffa853d11441e7ad94cb47bacd91b023499b51cbc756 \
@@ -22,10 +22,10 b' contextlib2==0.5.5 \\'
     --hash=sha256:509f9419ee91cdd00ba34443217d5ca51f5a364a404e1dce9e8979cea969ca48 \
     --hash=sha256:f5260a6e679d2ff42ec91ec5252f4eeffdcf21053db9113bd0a8e4d953769c00 \
     # via vcrpy
-docutils==0.14 \
-    --hash=sha256:02aec4bd92ab067f6ff27a38a38a41173bf01bed8f89157768c1573f53e474a6 \
-    --hash=sha256:51e64ef2ebfb29cae1faa133b3710143496eca21c530f3f71424d77687764274 \
-    --hash=sha256:7a4bd47eaf6596e1295ecb11361139febe29b084a87bf005bf899f9a42edc3c6
+docutils==0.15.2 \
+    --hash=sha256:6c4f696463b79f1fb8ba0c594b63840ebd41f059e92b31957c46b74a4599b6d0 \
+    --hash=sha256:9e4d7ecfc600058e07ba661411a2b7de2fd0fafa17d1a7f7361cd47b1175c827 \
+    --hash=sha256:a2aeea129088da402665e92e0b25b04b073c04b2dce4ab65caaa38b7ce2e1a99
 enum34==1.1.6 \
     --hash=sha256:2d81cbbe0e73112bdfe6ef8576f2238f2ba27dd0d55752a776c41d38b7da2850 \
     --hash=sha256:644837f692e5f550741432dd3f223bbb9852018674981b1664e5dc339387588a \
@@ -36,83 +36,70 b' funcsigs==1.0.2 \\'
     --hash=sha256:330cc27ccbf7f1e992e69fef78261dc7c6569012cf397db8d3de0234e6c937ca \
     --hash=sha256:a7bb0f2cf3a3fd1ab2732cb49eba4252c2af4240442415b4abce3b87022a8f50 \
     # via mock
-futures==3.2.0 \
-    --hash=sha256:9ec02aa7d674acb8618afb127e27fde7fc68994c0437ad759fa094a574adb265 \
-    --hash=sha256:ec0a6cb848cc212002b9828c3e34c675e0c9ff6741dc445cab6fdd4e1085d1f1 \
+futures==3.3.0 \
+    --hash=sha256:49b3f5b064b6e3afc3316421a3f25f66c137ae88f068abbf72830170033c5e16 \
+    --hash=sha256:7e033af76a5e35f58e56da7a91e687706faf4e7bdfb2cbc3f2cca6b9bcda9794 \
     # via isort
 fuzzywuzzy==0.17.0 \
     --hash=sha256:5ac7c0b3f4658d2743aa17da53a55598144edbc5bee3c6863840636e6926f254 \
     --hash=sha256:6f49de47db00e1c71d40ad16da42284ac357936fa9b66bea1df63fed07122d62
-isort==4.3.17 \
-    --hash=sha256:01cb7e1ca5e6c5b3f235f0385057f70558b70d2f00320208825fa62887292f43 \
-    --hash=sha256:268067462aed7eb2a1e237fcb287852f22077de3fb07964e87e00f829eea2d1a \
+isort==4.3.21 \
+    --hash=sha256:54da7e92468955c4fceacd0c86bd0ec997b0e1ee80d97f67c35a78b719dccab1 \
+    --hash=sha256:6e811fcb295968434526407adb8796944f1988c5b65e8139058f2014cbe100fd \
     # via pylint
-lazy-object-proxy==1.3.1 \
-    --hash=sha256:0ce34342b419bd8f018e6666bfef729aec3edf62345a53b537a4dcc115746a33 \
-    --hash=sha256:1b668120716eb7ee21d8a38815e5eb3bb8211117d9a90b0f8e21722c0758cc39 \
-    --hash=sha256:209615b0fe4624d79e50220ce3310ca1a9445fd8e6d3572a896e7f9146bbf019 \
-    --hash=sha256:27bf62cb2b1a2068d443ff7097ee33393f8483b570b475db8ebf7e1cba64f088 \
-    --hash=sha256:27ea6fd1c02dcc78172a82fc37fcc0992a94e4cecf53cb6d73f11749825bd98b \
-    --hash=sha256:2c1b21b44ac9beb0fc848d3993924147ba45c4ebc24be19825e57aabbe74a99e \
-    --hash=sha256:2df72ab12046a3496a92476020a1a0abf78b2a7db9ff4dc2036b8dd980203ae6 \
-    --hash=sha256:320ffd3de9699d3892048baee45ebfbbf9388a7d65d832d7e580243ade426d2b \
-    --hash=sha256:50e3b9a464d5d08cc5227413db0d1c4707b6172e4d4d915c1c70e4de0bbff1f5 \
-    --hash=sha256:5276db7ff62bb7b52f77f1f51ed58850e315154249aceb42e7f4c611f0f847ff \
-    --hash=sha256:61a6cf00dcb1a7f0c773ed4acc509cb636af2d6337a08f362413c76b2b47a8dd \
-    --hash=sha256:6ae6c4cb59f199d8827c5a07546b2ab7e85d262acaccaacd49b62f53f7c456f7 \
-    --hash=sha256:7661d401d60d8bf15bb5da39e4dd72f5d764c5aff5a86ef52a042506e3e970ff \
-    --hash=sha256:7bd527f36a605c914efca5d3d014170b2cb184723e423d26b1fb2fd9108e264d \
-    --hash=sha256:7cb54db3535c8686ea12e9535eb087d32421184eacc6939ef15ef50f83a5e7e2 \
-    --hash=sha256:7f3a2d740291f7f2c111d86a1c4851b70fb000a6c8883a59660d95ad57b9df35 \
-    --hash=sha256:81304b7d8e9c824d058087dcb89144842c8e0dea6d281c031f59f0acf66963d4 \
-    --hash=sha256:933947e8b4fbe617a51528b09851685138b49d511af0b6c0da2539115d6d4514 \
-    --hash=sha256:94223d7f060301b3a8c09c9b3bc3294b56b2188e7d8179c762a1cda72c979252 \
-    --hash=sha256:ab3ca49afcb47058393b0122428358d2fbe0408cf99f1b58b295cfeb4ed39109 \
-    --hash=sha256:bd6292f565ca46dee4e737ebcc20742e3b5be2b01556dafe169f6c65d088875f \
-    --hash=sha256:cb924aa3e4a3fb644d0c463cad5bc2572649a6a3f68a7f8e4fbe44aaa6d77e4c \
-    --hash=sha256:d0fc7a286feac9077ec52a927fc9fe8fe2fabab95426722be4c953c9a8bede92 \
-    --hash=sha256:ddc34786490a6e4ec0a855d401034cbd1242ef186c20d79d2166d6a4bd449577 \
-    --hash=sha256:e34b155e36fa9da7e1b7c738ed7767fc9491a62ec6af70fe9da4a057759edc2d \
-    --hash=sha256:e5b9e8f6bda48460b7b143c3821b21b452cb3a835e6bbd5dd33aa0c8d3f5137d \
-    --hash=sha256:e81ebf6c5ee9684be8f2c87563880f93eedd56dd2b6146d8a725b50b7e5adb0f \
-    --hash=sha256:eb91be369f945f10d3a49f5f9be8b3d0b93a4c2be8f8a5b83b0571b8123e0a7a \
-    --hash=sha256:f460d1ceb0e4a5dcb2a652db0904224f367c9b3c1470d5a7683c0480e582468b \
+lazy-object-proxy==1.4.1 \
+    --hash=sha256:159a745e61422217881c4de71f9eafd9d703b93af95618635849fe469a283661 \
+    --hash=sha256:23f63c0821cc96a23332e45dfaa83266feff8adc72b9bcaef86c202af765244f \
+    --hash=sha256:3b11be575475db2e8a6e11215f5aa95b9ec14de658628776e10d96fa0b4dac13 \
+    --hash=sha256:3f447aff8bc61ca8b42b73304f6a44fa0d915487de144652816f950a3f1ab821 \
+    --hash=sha256:4ba73f6089cd9b9478bc0a4fa807b47dbdb8fad1d8f31a0f0a5dbf26a4527a71 \
+    --hash=sha256:4f53eadd9932055eac465bd3ca1bd610e4d7141e1278012bd1f28646aebc1d0e \
+    --hash=sha256:64483bd7154580158ea90de5b8e5e6fc29a16a9b4db24f10193f0c1ae3f9d1ea \
+    --hash=sha256:6f72d42b0d04bfee2397aa1862262654b56922c20a9bb66bb76b6f0e5e4f9229 \
+    --hash=sha256:7c7f1ec07b227bdc561299fa2328e85000f90179a2f44ea30579d38e037cb3d4 \
+    --hash=sha256:7c8b1ba1e15c10b13cad4171cfa77f5bb5ec2580abc5a353907780805ebe158e \
+    --hash=sha256:8559b94b823f85342e10d3d9ca4ba5478168e1ac5658a8a2f18c991ba9c52c20 \
+    --hash=sha256:a262c7dfb046f00e12a2bdd1bafaed2408114a89ac414b0af8755c696eb3fc16 \
+    --hash=sha256:acce4e3267610c4fdb6632b3886fe3f2f7dd641158a843cf6b6a68e4ce81477b \
+    --hash=sha256:be089bb6b83fac7f29d357b2dc4cf2b8eb8d98fe9d9ff89f9ea6012970a853c7 \
+    --hash=sha256:bfab710d859c779f273cc48fb86af38d6e9210f38287df0069a63e40b45a2f5c \
+    --hash=sha256:c10d29019927301d524a22ced72706380de7cfc50f767217485a912b4c8bd82a \
+    --hash=sha256:dd6e2b598849b3d7aee2295ac765a578879830fb8966f70be8cd472e6069932e \
+    --hash=sha256:e408f1eacc0a68fed0c08da45f31d0ebb38079f043328dce69ff133b95c29dc1 \
     # via astroid
 mccabe==0.6.1 \
     --hash=sha256:ab8a6258860da4b6677da4bd2fe5dc2c659cff31b3ee4f7f5d64e79735b80d42 \
     --hash=sha256:dd8d182285a0fe56bace7f45b5e7d1a6ebcbf524e8f3bd87eb0f125271b8831f \
     # via pylint
-mock==2.0.0 \
-    --hash=sha256:5ce3c71c5545b472da17b72268978914d0252980348636840bd34a00b5cc96c1 \
-    --hash=sha256:b158b6df76edd239b8208d481dc46b6afd45a846b7812ff0ce58971cf5bc8bba \
+mock==3.0.5 \
+    --hash=sha256:83657d894c90d5681d62155c82bda9c1187827525880eda8ff5df4ec813437c3 \
+    --hash=sha256:d157e52d4e5b938c550f39eb2fd15610db062441a9c2747d3dbfa9298211d0f8 \
     # via vcrpy
-pbr==5.1.3 \
-    --hash=sha256:8257baf496c8522437e8a6cfe0f15e00aedc6c0e0e7c9d55eeeeab31e0853843 \
-    --hash=sha256:8c361cc353d988e4f5b998555c88098b9d5964c2e11acf7b0d21925a66bb5824 \
-    # via mock
 pyflakes==2.1.1 \
     --hash=sha256:17dbeb2e3f4d772725c777fabc446d5634d1038f234e77343108ce445ea69ce0 \
     --hash=sha256:d976835886f8c5b31d47970ed689944a0262b5f3afa00a5a7b4dc81e5449f8a2
-pygments==2.3.1 \
-    --hash=sha256:5ffada19f6203563680669ee7f53b64dabbeb100eb51b61996085e99c03b284a \
-    --hash=sha256:e8218dd399a61674745138520d0d4cf2621d7e032439341bc3f647bff125818d
-pylint==1.9.4 \
-    --hash=sha256:02c2b6d268695a8b64ad61847f92e611e6afcff33fd26c3a2125370c4662905d \
-    --hash=sha256:ee1e85575587c5b58ddafa25e1c1b01691ef172e139fc25585e5d3f02451da93
+pygments==2.4.2 \
+    --hash=sha256:71e430bc85c88a430f000ac1d9b331d2407f681d6f6aec95e8bcfbc3df5b0127 \
+    --hash=sha256:881c4c157e45f30af185c1ffe8d549d48ac9127433f2c380c24b84572ad66297
+pylint==1.9.5 \
+    --hash=sha256:367e3d49813d349a905390ac27989eff82ab84958731c5ef0bef867452cfdc42 \
+    --hash=sha256:97a42df23d436c70132971d1dcb9efad2fe5c0c6add55b90161e773caf729300
 python-levenshtein==0.12.0 \
     --hash=sha256:033a11de5e3d19ea25c9302d11224e1a1898fe5abd23c61c7c360c25195e3eb1
-pyyaml==5.1 \
-    --hash=sha256:1adecc22f88d38052fb787d959f003811ca858b799590a5eaa70e63dca50308c \
-    --hash=sha256:436bc774ecf7c103814098159fbb84c2715d25980175292c648f2da143909f95 \
-    --hash=sha256:460a5a4248763f6f37ea225d19d5c205677d8d525f6a83357ca622ed541830c2 \
-    --hash=sha256:5a22a9c84653debfbf198d02fe592c176ea548cccce47553f35f466e15cf2fd4 \
-    --hash=sha256:7a5d3f26b89d688db27822343dfa25c599627bc92093e788956372285c6298ad \
-    --hash=sha256:9372b04a02080752d9e6f990179a4ab840227c6e2ce15b95e1278456664cf2ba \
-    --hash=sha256:a5dcbebee834eaddf3fa7366316b880ff4062e4bcc9787b78c7fbb4a26ff2dd1 \
-    --hash=sha256:aee5bab92a176e7cd034e57f46e9df9a9862a71f8f37cad167c6fc74c65f5b4e \
-    --hash=sha256:c51f642898c0bacd335fc119da60baae0824f2cde95b0330b56c0553439f0673 \
-    --hash=sha256:c68ea4d3ba1705da1e0d85da6684ac657912679a649e8868bd850d2c299cce13 \
-    --hash=sha256:e23d0cc5299223dcc37885dae624f382297717e459ea24053709675a976a3e19 \
+pyyaml==5.1.2 \
+    --hash=sha256:0113bc0ec2ad727182326b61326afa3d1d8280ae1122493553fd6f4397f33df9 \
+    --hash=sha256:01adf0b6c6f61bd11af6e10ca52b7d4057dd0be0343eb9283c878cf3af56aee4 \
+    --hash=sha256:5124373960b0b3f4aa7df1707e63e9f109b5263eca5976c66e08b1c552d4eaf8 \
+    --hash=sha256:5ca4f10adbddae56d824b2c09668e91219bb178a1eee1faa56af6f99f11bf696 \
+    --hash=sha256:7907be34ffa3c5a32b60b95f4d95ea25361c951383a894fec31be7252b2b6f34 \
+    --hash=sha256:7ec9b2a4ed5cad025c2278a1e6a19c011c80a3caaac804fd2d329e9cc2c287c9 \
+    --hash=sha256:87ae4c829bb25b9fe99cf71fbb2140c448f534e24c998cc60f39ae4f94396a73 \
+    --hash=sha256:9de9919becc9cc2ff03637872a440195ac4241c80536632fffeb6a1e25a74299 \
+    --hash=sha256:a5a85b10e450c66b49f98846937e8cfca1db3127a9d5d1e31ca45c3d0bef4c5b \
+    --hash=sha256:b0997827b4f6a7c286c01c5f60384d218dca4ed7d9efa945c3e1aa623d5709ae \
+    --hash=sha256:b631ef96d3222e62861443cc89d6563ba3eeb816eeb96b2629345ab795e53681 \
+    --hash=sha256:bf47c0607522fdbca6c9e817a6e81b08491de50f3766a7a0e6a5be7905961b41 \
+    --hash=sha256:f81025eddd0327c7d4cfe9b62cf33190e1e736cc6e97502b3ec425f574b3e7a8 \
     # via vcrpy
 singledispatch==3.4.0.3 \
     --hash=sha256:5b06af87df13818d14f08a028e42f566640aef80805c3b50c5056b086e3c2b9c \
@@ -125,6 +112,10 b' six==1.12.0 \\'
 vcrpy==2.0.1 \
     --hash=sha256:127e79cf7b569d071d1bd761b83f7b62b2ce2a2eb63ceca7aa67cba8f2602ea3 \
     --hash=sha256:57be64aa8e9883a4117d0b15de28af62275c001abcdb00b6dc2d4406073d9a4f
-wrapt==1.11.1 \
-    --hash=sha256:4aea003270831cceb8a90ff27c4031da6ead7ec1886023b80ce0dfe0adf61533 \
+wrapt==1.11.2 \
+    --hash=sha256:565a021fd19419476b9362b05eeaa094178de64f8361e44468f9e9d7843901e1 \
     # via astroid, vcrpy
+
+# WARNING: The following packages were not pinned, but pip requires them to be
+# pinned when the requirements file includes hashes. Consider using the --allow-unsafe flag.
+# setuptools==41.0.1        # via python-levenshtein

contrib/automation/linux-requirements-py3.txt

@@ -2,16 +2,16 b''
 # This file is autogenerated by pip-compile
 # To update, run:
 #
-#    pip-compile -U --generate-hashes --output-file contrib/automation/linux-requirements-py3.txt contrib/automation/linux-requirements.txt.in
+#    pip-compile --generate-hashes --output-file=contrib/automation/linux-requirements-py3.txt contrib/automation/linux-requirements.txt.in
 #
 astroid==2.2.5 \
     --hash=sha256:6560e1e1749f68c64a4b5dee4e091fce798d2f0d84ebe638cf0e0585a343acf4 \
     --hash=sha256:b65db1bbaac9f9f4d190199bb8680af6f6f84fd3769a5ea883df8a91fe68b4c4 \
     # via pylint
-docutils==0.14 \
-    --hash=sha256:02aec4bd92ab067f6ff27a38a38a41173bf01bed8f89157768c1573f53e474a6 \
-    --hash=sha256:51e64ef2ebfb29cae1faa133b3710143496eca21c530f3f71424d77687764274 \
-    --hash=sha256:7a4bd47eaf6596e1295ecb11361139febe29b084a87bf005bf899f9a42edc3c6
+docutils==0.15.2 \
+    --hash=sha256:6c4f696463b79f1fb8ba0c594b63840ebd41f059e92b31957c46b74a4599b6d0 \
+    --hash=sha256:9e4d7ecfc600058e07ba661411a2b7de2fd0fafa17d1a7f7361cd47b1175c827 \
+    --hash=sha256:a2aeea129088da402665e92e0b25b04b073c04b2dce4ab65caaa38b7ce2e1a99
 fuzzywuzzy==0.17.0 \
     --hash=sha256:5ac7c0b3f4658d2743aa17da53a55598144edbc5bee3c6863840636e6926f254 \
     --hash=sha256:6f49de47db00e1c71d40ad16da42284ac357936fa9b66bea1df63fed07122d62
@@ -19,40 +19,29 b' idna==2.8 \\'
     --hash=sha256:c357b3f628cf53ae2c4c05627ecc484553142ca23264e593d327bcde5e9c3407 \
     --hash=sha256:ea8b7f6188e6fa117537c3df7da9fc686d485087abf6ac197f9c46432f7e4a3c \
     # via yarl
-isort==4.3.17 \
-    --hash=sha256:01cb7e1ca5e6c5b3f235f0385057f70558b70d2f00320208825fa62887292f43 \
-    --hash=sha256:268067462aed7eb2a1e237fcb287852f22077de3fb07964e87e00f829eea2d1a \
+isort==4.3.21 \
+    --hash=sha256:54da7e92468955c4fceacd0c86bd0ec997b0e1ee80d97f67c35a78b719dccab1 \
+    --hash=sha256:6e811fcb295968434526407adb8796944f1988c5b65e8139058f2014cbe100fd \
     # via pylint
-lazy-object-proxy==1.3.1 \
-    --hash=sha256:0ce34342b419bd8f018e6666bfef729aec3edf62345a53b537a4dcc115746a33 \
-    --hash=sha256:1b668120716eb7ee21d8a38815e5eb3bb8211117d9a90b0f8e21722c0758cc39 \
-    --hash=sha256:209615b0fe4624d79e50220ce3310ca1a9445fd8e6d3572a896e7f9146bbf019 \
-    --hash=sha256:27bf62cb2b1a2068d443ff7097ee33393f8483b570b475db8ebf7e1cba64f088 \
-    --hash=sha256:27ea6fd1c02dcc78172a82fc37fcc0992a94e4cecf53cb6d73f11749825bd98b \
-    --hash=sha256:2c1b21b44ac9beb0fc848d3993924147ba45c4ebc24be19825e57aabbe74a99e \
-    --hash=sha256:2df72ab12046a3496a92476020a1a0abf78b2a7db9ff4dc2036b8dd980203ae6 \
-    --hash=sha256:320ffd3de9699d3892048baee45ebfbbf9388a7d65d832d7e580243ade426d2b \
-    --hash=sha256:50e3b9a464d5d08cc5227413db0d1c4707b6172e4d4d915c1c70e4de0bbff1f5 \
-    --hash=sha256:5276db7ff62bb7b52f77f1f51ed58850e315154249aceb42e7f4c611f0f847ff \
-    --hash=sha256:61a6cf00dcb1a7f0c773ed4acc509cb636af2d6337a08f362413c76b2b47a8dd \
-    --hash=sha256:6ae6c4cb59f199d8827c5a07546b2ab7e85d262acaccaacd49b62f53f7c456f7 \
-    --hash=sha256:7661d401d60d8bf15bb5da39e4dd72f5d764c5aff5a86ef52a042506e3e970ff \
-    --hash=sha256:7bd527f36a605c914efca5d3d014170b2cb184723e423d26b1fb2fd9108e264d \
-    --hash=sha256:7cb54db3535c8686ea12e9535eb087d32421184eacc6939ef15ef50f83a5e7e2 \
-    --hash=sha256:7f3a2d740291f7f2c111d86a1c4851b70fb000a6c8883a59660d95ad57b9df35 \
-    --hash=sha256:81304b7d8e9c824d058087dcb89144842c8e0dea6d281c031f59f0acf66963d4 \
-    --hash=sha256:933947e8b4fbe617a51528b09851685138b49d511af0b6c0da2539115d6d4514 \
-    --hash=sha256:94223d7f060301b3a8c09c9b3bc3294b56b2188e7d8179c762a1cda72c979252 \
-    --hash=sha256:ab3ca49afcb47058393b0122428358d2fbe0408cf99f1b58b295cfeb4ed39109 \
-    --hash=sha256:bd6292f565ca46dee4e737ebcc20742e3b5be2b01556dafe169f6c65d088875f \
-    --hash=sha256:cb924aa3e4a3fb644d0c463cad5bc2572649a6a3f68a7f8e4fbe44aaa6d77e4c \
-    --hash=sha256:d0fc7a286feac9077ec52a927fc9fe8fe2fabab95426722be4c953c9a8bede92 \
-    --hash=sha256:ddc34786490a6e4ec0a855d401034cbd1242ef186c20d79d2166d6a4bd449577 \
-    --hash=sha256:e34b155e36fa9da7e1b7c738ed7767fc9491a62ec6af70fe9da4a057759edc2d \
-    --hash=sha256:e5b9e8f6bda48460b7b143c3821b21b452cb3a835e6bbd5dd33aa0c8d3f5137d \
-    --hash=sha256:e81ebf6c5ee9684be8f2c87563880f93eedd56dd2b6146d8a725b50b7e5adb0f \
-    --hash=sha256:eb91be369f945f10d3a49f5f9be8b3d0b93a4c2be8f8a5b83b0571b8123e0a7a \
-    --hash=sha256:f460d1ceb0e4a5dcb2a652db0904224f367c9b3c1470d5a7683c0480e582468b \
+lazy-object-proxy==1.4.1 \
+    --hash=sha256:159a745e61422217881c4de71f9eafd9d703b93af95618635849fe469a283661 \
+    --hash=sha256:23f63c0821cc96a23332e45dfaa83266feff8adc72b9bcaef86c202af765244f \
+    --hash=sha256:3b11be575475db2e8a6e11215f5aa95b9ec14de658628776e10d96fa0b4dac13 \
+    --hash=sha256:3f447aff8bc61ca8b42b73304f6a44fa0d915487de144652816f950a3f1ab821 \
+    --hash=sha256:4ba73f6089cd9b9478bc0a4fa807b47dbdb8fad1d8f31a0f0a5dbf26a4527a71 \
+    --hash=sha256:4f53eadd9932055eac465bd3ca1bd610e4d7141e1278012bd1f28646aebc1d0e \
+    --hash=sha256:64483bd7154580158ea90de5b8e5e6fc29a16a9b4db24f10193f0c1ae3f9d1ea \
+    --hash=sha256:6f72d42b0d04bfee2397aa1862262654b56922c20a9bb66bb76b6f0e5e4f9229 \
+    --hash=sha256:7c7f1ec07b227bdc561299fa2328e85000f90179a2f44ea30579d38e037cb3d4 \
+    --hash=sha256:7c8b1ba1e15c10b13cad4171cfa77f5bb5ec2580abc5a353907780805ebe158e \
+    --hash=sha256:8559b94b823f85342e10d3d9ca4ba5478168e1ac5658a8a2f18c991ba9c52c20 \
+    --hash=sha256:a262c7dfb046f00e12a2bdd1bafaed2408114a89ac414b0af8755c696eb3fc16 \
+    --hash=sha256:acce4e3267610c4fdb6632b3886fe3f2f7dd641158a843cf6b6a68e4ce81477b \
+    --hash=sha256:be089bb6b83fac7f29d357b2dc4cf2b8eb8d98fe9d9ff89f9ea6012970a853c7 \
+    --hash=sha256:bfab710d859c779f273cc48fb86af38d6e9210f38287df0069a63e40b45a2f5c \
+    --hash=sha256:c10d29019927301d524a22ced72706380de7cfc50f767217485a912b4c8bd82a \
+    --hash=sha256:dd6e2b598849b3d7aee2295ac765a578879830fb8966f70be8cd472e6069932e \
+    --hash=sha256:e408f1eacc0a68fed0c08da45f31d0ebb38079f043328dce69ff133b95c29dc1 \
     # via astroid
 mccabe==0.6.1 \
     --hash=sha256:ab8a6258860da4b6677da4bd2fe5dc2c659cff31b3ee4f7f5d64e79735b80d42 \
@@ -92,57 +81,54 b' multidict==4.5.2 \\'
 pyflakes==2.1.1 \
     --hash=sha256:17dbeb2e3f4d772725c777fabc446d5634d1038f234e77343108ce445ea69ce0 \
     --hash=sha256:d976835886f8c5b31d47970ed689944a0262b5f3afa00a5a7b4dc81e5449f8a2
-pygments==2.3.1 \
-    --hash=sha256:5ffada19f6203563680669ee7f53b64dabbeb100eb51b61996085e99c03b284a \
-    --hash=sha256:e8218dd399a61674745138520d0d4cf2621d7e032439341bc3f647bff125818d
+pygments==2.4.2 \
+    --hash=sha256:71e430bc85c88a430f000ac1d9b331d2407f681d6f6aec95e8bcfbc3df5b0127 \
+    --hash=sha256:881c4c157e45f30af185c1ffe8d549d48ac9127433f2c380c24b84572ad66297
 pylint==2.3.1 \
     --hash=sha256:5d77031694a5fb97ea95e828c8d10fc770a1df6eb3906067aaed42201a8a6a09 \
     --hash=sha256:723e3db49555abaf9bf79dc474c6b9e2935ad82230b10c1138a71ea41ac0fff1
 python-levenshtein==0.12.0 \
     --hash=sha256:033a11de5e3d19ea25c9302d11224e1a1898fe5abd23c61c7c360c25195e3eb1
-pyyaml==5.1 \
-    --hash=sha256:1adecc22f88d38052fb787d959f003811ca858b799590a5eaa70e63dca50308c \
-    --hash=sha256:436bc774ecf7c103814098159fbb84c2715d25980175292c648f2da143909f95 \
-    --hash=sha256:460a5a4248763f6f37ea225d19d5c205677d8d525f6a83357ca622ed541830c2 \
-    --hash=sha256:5a22a9c84653debfbf198d02fe592c176ea548cccce47553f35f466e15cf2fd4 \
-    --hash=sha256:7a5d3f26b89d688db27822343dfa25c599627bc92093e788956372285c6298ad \
-    --hash=sha256:9372b04a02080752d9e6f990179a4ab840227c6e2ce15b95e1278456664cf2ba \
-    --hash=sha256:a5dcbebee834eaddf3fa7366316b880ff4062e4bcc9787b78c7fbb4a26ff2dd1 \
-    --hash=sha256:aee5bab92a176e7cd034e57f46e9df9a9862a71f8f37cad167c6fc74c65f5b4e \
-    --hash=sha256:c51f642898c0bacd335fc119da60baae0824f2cde95b0330b56c0553439f0673 \
-    --hash=sha256:c68ea4d3ba1705da1e0d85da6684ac657912679a649e8868bd850d2c299cce13 \
-    --hash=sha256:e23d0cc5299223dcc37885dae624f382297717e459ea24053709675a976a3e19 \
+pyyaml==5.1.2 \
+    --hash=sha256:0113bc0ec2ad727182326b61326afa3d1d8280ae1122493553fd6f4397f33df9 \
+    --hash=sha256:01adf0b6c6f61bd11af6e10ca52b7d4057dd0be0343eb9283c878cf3af56aee4 \
+    --hash=sha256:5124373960b0b3f4aa7df1707e63e9f109b5263eca5976c66e08b1c552d4eaf8 \
+    --hash=sha256:5ca4f10adbddae56d824b2c09668e91219bb178a1eee1faa56af6f99f11bf696 \
+    --hash=sha256:7907be34ffa3c5a32b60b95f4d95ea25361c951383a894fec31be7252b2b6f34 \
+    --hash=sha256:7ec9b2a4ed5cad025c2278a1e6a19c011c80a3caaac804fd2d329e9cc2c287c9 \
+    --hash=sha256:87ae4c829bb25b9fe99cf71fbb2140c448f534e24c998cc60f39ae4f94396a73 \
+    --hash=sha256:9de9919becc9cc2ff03637872a440195ac4241c80536632fffeb6a1e25a74299 \
+    --hash=sha256:a5a85b10e450c66b49f98846937e8cfca1db3127a9d5d1e31ca45c3d0bef4c5b \
+    --hash=sha256:b0997827b4f6a7c286c01c5f60384d218dca4ed7d9efa945c3e1aa623d5709ae \
+    --hash=sha256:b631ef96d3222e62861443cc89d6563ba3eeb816eeb96b2629345ab795e53681 \
+    --hash=sha256:bf47c0607522fdbca6c9e817a6e81b08491de50f3766a7a0e6a5be7905961b41 \
+    --hash=sha256:f81025eddd0327c7d4cfe9b62cf33190e1e736cc6e97502b3ec425f574b3e7a8 \
     # via vcrpy
 six==1.12.0 \
     --hash=sha256:3350809f0555b11f552448330d0b52d5f24c91a322ea4a15ef22629740f3761c \
     --hash=sha256:d16a0141ec1a18405cd4ce8b4613101da75da0e9a7aec5bdd4fa804d0e0eba73 \
     # via astroid, vcrpy
-typed-ast==1.3.4 ; python_version >= "3.0" and platform_python_implementation != "PyPy" \
-    --hash=sha256:04894d268ba6eab7e093d43107869ad49e7b5ef40d1a94243ea49b352061b200 \
-    --hash=sha256:16616ece19daddc586e499a3d2f560302c11f122b9c692bc216e821ae32aa0d0 \
-    --hash=sha256:252fdae740964b2d3cdfb3f84dcb4d6247a48a6abe2579e8029ab3be3cdc026c \
-    --hash=sha256:2af80a373af123d0b9f44941a46df67ef0ff7a60f95872412a145f4500a7fc99 \
-    --hash=sha256:2c88d0a913229a06282b285f42a31e063c3bf9071ff65c5ea4c12acb6977c6a7 \
-    --hash=sha256:2ea99c029ebd4b5a308d915cc7fb95b8e1201d60b065450d5d26deb65d3f2bc1 \
-    --hash=sha256:3d2e3ab175fc097d2a51c7a0d3fda442f35ebcc93bb1d7bd9b95ad893e44c04d \
-    --hash=sha256:4766dd695548a15ee766927bf883fb90c6ac8321be5a60c141f18628fb7f8da8 \
-    --hash=sha256:56b6978798502ef66625a2e0f80cf923da64e328da8bbe16c1ff928c70c873de \
-    --hash=sha256:5cddb6f8bce14325b2863f9d5ac5c51e07b71b462361fd815d1d7706d3a9d682 \
-    --hash=sha256:644ee788222d81555af543b70a1098f2025db38eaa99226f3a75a6854924d4db \
-    --hash=sha256:64cf762049fc4775efe6b27161467e76d0ba145862802a65eefc8879086fc6f8 \
-    --hash=sha256:68c362848d9fb71d3c3e5f43c09974a0ae319144634e7a47db62f0f2a54a7fa7 \
-    --hash=sha256:6c1f3c6f6635e611d58e467bf4371883568f0de9ccc4606f17048142dec14a1f \
-    --hash=sha256:b213d4a02eec4ddf622f4d2fbc539f062af3788d1f332f028a2e19c42da53f15 \
-    --hash=sha256:bb27d4e7805a7de0e35bd0cb1411bc85f807968b2b0539597a49a23b00a622ae \
-    --hash=sha256:c9d414512eaa417aadae7758bc118868cd2396b0e6138c1dd4fda96679c079d3 \
-    --hash=sha256:f0937165d1e25477b01081c4763d2d9cdc3b18af69cb259dd4f640c9b900fe5e \
-    --hash=sha256:fb96a6e2c11059ecf84e6741a319f93f683e440e341d4489c9b161eca251cf2a \
-    --hash=sha256:fc71d2d6ae56a091a8d94f33ec9d0f2001d1cb1db423d8b4355debfe9ce689b7
+typed-ast==1.4.0 ; python_version >= "3.0" and platform_python_implementation != "PyPy" \
+    --hash=sha256:18511a0b3e7922276346bcb47e2ef9f38fb90fd31cb9223eed42c85d1312344e \
+    --hash=sha256:262c247a82d005e43b5b7f69aff746370538e176131c32dda9cb0f324d27141e \
+    --hash=sha256:2b907eb046d049bcd9892e3076c7a6456c93a25bebfe554e931620c90e6a25b0 \
+    --hash=sha256:354c16e5babd09f5cb0ee000d54cfa38401d8b8891eefa878ac772f827181a3c \
+    --hash=sha256:4e0b70c6fc4d010f8107726af5fd37921b666f5b31d9331f0bd24ad9a088e631 \
+    --hash=sha256:630968c5cdee51a11c05a30453f8cd65e0cc1d2ad0d9192819df9978984529f4 \
+    --hash=sha256:66480f95b8167c9c5c5c87f32cf437d585937970f3fc24386f313a4c97b44e34 \
+    --hash=sha256:71211d26ffd12d63a83e079ff258ac9d56a1376a25bc80b1cdcdf601b855b90b \
+    --hash=sha256:95bd11af7eafc16e829af2d3df510cecfd4387f6453355188342c3e79a2ec87a \
+    --hash=sha256:bc6c7d3fa1325a0c6613512a093bc2a2a15aeec350451cbdf9e1d4bffe3e3233 \
+    --hash=sha256:cc34a6f5b426748a507dd5d1de4c1978f2eb5626d51326e43280941206c209e1 \
+    --hash=sha256:d755f03c1e4a51e9b24d899561fec4ccaf51f210d52abdf8c07ee2849b212a36 \
+    --hash=sha256:d7c45933b1bdfaf9f36c579671fec15d25b06c8398f113dab64c18ed1adda01d \
+    --hash=sha256:d896919306dd0aa22d0132f62a1b78d11aaf4c9fc5b3410d3c666b818191630a \
+    --hash=sha256:ffde2fbfad571af120fcbfbbc61c72469e72f550d676c3342492a9dfdefb8f12
 vcrpy==2.0.1 \
     --hash=sha256:127e79cf7b569d071d1bd761b83f7b62b2ce2a2eb63ceca7aa67cba8f2602ea3 \
     --hash=sha256:57be64aa8e9883a4117d0b15de28af62275c001abcdb00b6dc2d4406073d9a4f
-wrapt==1.11.1 \
-    --hash=sha256:4aea003270831cceb8a90ff27c4031da6ead7ec1886023b80ce0dfe0adf61533 \
+wrapt==1.11.2 \
+    --hash=sha256:565a021fd19419476b9362b05eeaa094178de64f8361e44468f9e9d7843901e1 \
     # via astroid, vcrpy
 yarl==1.3.0 \
     --hash=sha256:024ecdc12bc02b321bc66b41327f930d1c2c543fa9a561b39861da9388ba7aa9 \
@@ -157,3 +143,7 b' yarl==1.3.0 \\'
     --hash=sha256:c9bb7c249c4432cd47e75af3864bc02d26c9594f49c82e2a28624417f0ae63b8 \
     --hash=sha256:e060906c0c585565c718d1c3841747b61c5439af2211e185f6739a9412dfbde1 \
     # via vcrpy
+
+# WARNING: The following packages were not pinned, but pip requires them to be
+# pinned when the requirements file includes hashes. Consider using the --allow-unsafe flag.
+# setuptools==41.0.1        # via python-levenshtein

contrib/automation/requirements.txt

@@ -2,43 +2,44 b''
 # This file is autogenerated by pip-compile
 # To update, run:
 #
-#    pip-compile -U --generate-hashes --output-file contrib/automation/requirements.txt contrib/automation/requirements.txt.in
+#    pip-compile --generate-hashes --output-file=contrib/automation/requirements.txt contrib/automation/requirements.txt.in
 #
-asn1crypto==0.24.0 \
-    --hash=sha256:2f1adbb7546ed199e3c90ef23ec95c5cf3585bac7d11fb7eb562a3fe89c64e87 \
-    --hash=sha256:9d5c20441baf0cb60a4ac34cc447c6c189024b6b4c6cd7877034f4965c464e49 \
+asn1crypto==1.0.1 \
+    --hash=sha256:0b199f211ae690df3db4fd6c1c4ff976497fb1da689193e368eedbadc53d9292 \
+    --hash=sha256:bca90060bd995c3f62c4433168eab407e44bdbdb567b3f3a396a676c1a4c4a3f \
     # via cryptography
-bcrypt==3.1.6 \
-    --hash=sha256:0ba875eb67b011add6d8c5b76afbd92166e98b1f1efab9433d5dc0fafc76e203 \
-    --hash=sha256:21ed446054c93e209434148ef0b362432bb82bbdaf7beef70a32c221f3e33d1c \
-    --hash=sha256:28a0459381a8021f57230954b9e9a65bb5e3d569d2c253c5cac6cb181d71cf23 \
-    --hash=sha256:2aed3091eb6f51c26b7c2fad08d6620d1c35839e7a362f706015b41bd991125e \
-    --hash=sha256:2fa5d1e438958ea90eaedbf8082c2ceb1a684b4f6c75a3800c6ec1e18ebef96f \
-    --hash=sha256:3a73f45484e9874252002793518da060fb11eaa76c30713faa12115db17d1430 \
-    --hash=sha256:3e489787638a36bb466cd66780e15715494b6d6905ffdbaede94440d6d8e7dba \
-    --hash=sha256:44636759d222baa62806bbceb20e96f75a015a6381690d1bc2eda91c01ec02ea \
-    --hash=sha256:678c21b2fecaa72a1eded0cf12351b153615520637efcadc09ecf81b871f1596 \
-    --hash=sha256:75460c2c3786977ea9768d6c9d8957ba31b5fbeb0aae67a5c0e96aab4155f18c \
-    --hash=sha256:8ac06fb3e6aacb0a95b56eba735c0b64df49651c6ceb1ad1cf01ba75070d567f \
-    --hash=sha256:8fdced50a8b646fff8fa0e4b1c5fd940ecc844b43d1da5a980cb07f2d1b1132f \
-    --hash=sha256:9b2c5b640a2da533b0ab5f148d87fb9989bf9bcb2e61eea6a729102a6d36aef9 \
-    --hash=sha256:a9083e7fa9adb1a4de5ac15f9097eb15b04e2c8f97618f1b881af40abce382e1 \
-    --hash=sha256:b7e3948b8b1a81c5a99d41da5fb2dc03ddb93b5f96fcd3fd27e643f91efa33e1 \
-    --hash=sha256:b998b8ca979d906085f6a5d84f7b5459e5e94a13fc27c28a3514437013b6c2f6 \
-    --hash=sha256:dd08c50bc6f7be69cd7ba0769acca28c846ec46b7a8ddc2acf4b9ac6f8a7457e \
-    --hash=sha256:de5badee458544ab8125e63e39afeedfcf3aef6a6e2282ac159c95ae7472d773 \
-    --hash=sha256:ede2a87333d24f55a4a7338a6ccdccf3eaa9bed081d1737e0db4dbd1a4f7e6b6 \
+bcrypt==3.1.7 \
+    --hash=sha256:0258f143f3de96b7c14f762c770f5fc56ccd72f8a1857a451c1cd9a655d9ac89 \
+    --hash=sha256:0b0069c752ec14172c5f78208f1863d7ad6755a6fae6fe76ec2c80d13be41e42 \
+    --hash=sha256:19a4b72a6ae5bb467fea018b825f0a7d917789bcfe893e53f15c92805d187294 \
+    --hash=sha256:5432dd7b34107ae8ed6c10a71b4397f1c853bd39a4d6ffa7e35f40584cffd161 \
+    --hash=sha256:69361315039878c0680be456640f8705d76cb4a3a3fe1e057e0f261b74be4b31 \
+    --hash=sha256:6fe49a60b25b584e2f4ef175b29d3a83ba63b3a4df1b4c0605b826668d1b6be5 \
+    --hash=sha256:74a015102e877d0ccd02cdeaa18b32aa7273746914a6c5d0456dd442cb65b99c \
+    --hash=sha256:763669a367869786bb4c8fcf731f4175775a5b43f070f50f46f0b59da45375d0 \
+    --hash=sha256:8b10acde4e1919d6015e1df86d4c217d3b5b01bb7744c36113ea43d529e1c3de \
+    --hash=sha256:9fe92406c857409b70a38729dbdf6578caf9228de0aef5bc44f859ffe971a39e \
+    --hash=sha256:a190f2a5dbbdbff4b74e3103cef44344bc30e61255beb27310e2aec407766052 \
+    --hash=sha256:a595c12c618119255c90deb4b046e1ca3bcfad64667c43d1166f2b04bc72db09 \
+    --hash=sha256:c9457fa5c121e94a58d6505cadca8bed1c64444b83b3204928a866ca2e599105 \
+    --hash=sha256:cb93f6b2ab0f6853550b74e051d297c27a638719753eb9ff66d1e4072be67133 \
+    --hash=sha256:d7bdc26475679dd073ba0ed2766445bb5b20ca4793ca0db32b399dccc6bc84b7 \
+    --hash=sha256:ff032765bb8716d9387fd5376d987a937254b0619eff0972779515b5c98820bc \
     # via paramiko
-boto3==1.9.137 \
-    --hash=sha256:882cc4869b47b51dae4b4a900769e72171ff00e0b6bca644b2d7a7ad7378f324 \
-    --hash=sha256:cd503a7e7a04f1c14d2801f9727159dfa88c393b4004e98940fa4aa205d920c8
-botocore==1.12.137 \
-    --hash=sha256:0d95794f6b1239c75e2c5f966221bcd4b68020fddb5676f757531eedbb612ed8 \
-    --hash=sha256:3213cf48cf2ceee10fc3b93221f2cd1c38521cca7584f547d5c086213cc60f35 \
+bleach==3.1.0 \
+    --hash=sha256:213336e49e102af26d9cde77dd2d0397afabc5a6bf2fed985dc35b5d1e285a16 \
+    --hash=sha256:3fdf7f77adcf649c9911387df51254b813185e32b2c6619f690b593a617e19fa \
+    # via readme-renderer
+boto3==1.9.243 \
+    --hash=sha256:404acbecef8f4912f18312fcfaffe7eba7f10b3b7adf7853bdba59cdf2275ebb \
+    --hash=sha256:c6e5a7e4548ce7586c354ff633f2a66ba3c471d15a8ae6a30f873122ab04e1cf
+botocore==1.12.243 \
+    --hash=sha256:397585a7881230274afb8d1877ef69a661b0a311745cd324f14a052fb2a2863a \
+    --hash=sha256:4496f8da89cb496462a831897ad248e13e431d9fa7e41e06d426fd6658ab6e59 \
     # via boto3, s3transfer
-certifi==2019.3.9 \
-    --hash=sha256:59b7658e26ca9c7339e00f8f4636cdfe59d34fa37b9b04f6f9e9926b3cece1a5 \
-    --hash=sha256:b26104d6835d1f5e49452a26eb2ff87fe7090b89dfcaee5ea2212697e1e1d7ae \
+certifi==2019.9.11 \
+    --hash=sha256:e4f3620cfea4f83eedc95b24abd9cd56f3c4b146dd0177e83a21b4eb49e21e50 \
+    --hash=sha256:fd7c7c74727ddcf00e9acd26bba8da604ffec95bf1c2144e67aff7a8b50e6cef \
     # via requests
 cffi==1.12.3 \
     --hash=sha256:041c81822e9f84b1d9c401182e174996f0bae9991f33725d059b771744290774 \
@@ -74,32 +75,29 b' chardet==3.0.4 \\'
     --hash=sha256:84ab92ed1c4d4f16916e05906b6b75a6c0fb5db821cc65e70cbd64a3e2a5eaae \
     --hash=sha256:fc323ffcaeaed0e0a02bf4d117757b98aed530d9ed4531e3e15460124c106691 \
     # via requests
-cryptography==2.6.1 \
-    --hash=sha256:066f815f1fe46020877c5983a7e747ae140f517f1b09030ec098503575265ce1 \
-    --hash=sha256:210210d9df0afba9e000636e97810117dc55b7157c903a55716bb73e3ae07705 \
-    --hash=sha256:26c821cbeb683facb966045e2064303029d572a87ee69ca5a1bf54bf55f93ca6 \
-    --hash=sha256:2afb83308dc5c5255149ff7d3fb9964f7c9ee3d59b603ec18ccf5b0a8852e2b1 \
-    --hash=sha256:2db34e5c45988f36f7a08a7ab2b69638994a8923853dec2d4af121f689c66dc8 \
-    --hash=sha256:409c4653e0f719fa78febcb71ac417076ae5e20160aec7270c91d009837b9151 \
-    --hash=sha256:45a4f4cf4f4e6a55c8128f8b76b4c057027b27d4c67e3fe157fa02f27e37830d \
-    --hash=sha256:48eab46ef38faf1031e58dfcc9c3e71756a1108f4c9c966150b605d4a1a7f659 \
-    --hash=sha256:6b9e0ae298ab20d371fc26e2129fd683cfc0cfde4d157c6341722de645146537 \
-    --hash=sha256:6c4778afe50f413707f604828c1ad1ff81fadf6c110cb669579dea7e2e98a75e \
-    --hash=sha256:8c33fb99025d353c9520141f8bc989c2134a1f76bac6369cea060812f5b5c2bb \
-    --hash=sha256:9873a1760a274b620a135054b756f9f218fa61ca030e42df31b409f0fb738b6c \
-    --hash=sha256:9b069768c627f3f5623b1cbd3248c5e7e92aec62f4c98827059eed7053138cc9 \
-    --hash=sha256:9e4ce27a507e4886efbd3c32d120db5089b906979a4debf1d5939ec01b9dd6c5 \
-    --hash=sha256:acb424eaca214cb08735f1a744eceb97d014de6530c1ea23beb86d9c6f13c2ad \
-    --hash=sha256:c8181c7d77388fe26ab8418bb088b1a1ef5fde058c6926790c8a0a3d94075a4a \
-    --hash=sha256:d4afbb0840f489b60f5a580a41a1b9c3622e08ecb5eec8614d4fb4cd914c4460 \
-    --hash=sha256:d9ed28030797c00f4bc43c86bf819266c76a5ea61d006cd4078a93ebf7da6bfd \
-    --hash=sha256:e603aa7bb52e4e8ed4119a58a03b60323918467ef209e6ff9db3ac382e5cf2c6 \
+cryptography==2.7 \
+    --hash=sha256:24b61e5fcb506424d3ec4e18bca995833839bf13c59fc43e530e488f28d46b8c \
+    --hash=sha256:25dd1581a183e9e7a806fe0543f485103232f940fcfc301db65e630512cce643 \
+    --hash=sha256:3452bba7c21c69f2df772762be0066c7ed5dc65df494a1d53a58b683a83e1216 \
+    --hash=sha256:41a0be220dd1ed9e998f5891948306eb8c812b512dc398e5a01846d855050799 \
+    --hash=sha256:5751d8a11b956fbfa314f6553d186b94aa70fdb03d8a4d4f1c82dcacf0cbe28a \
+    --hash=sha256:5f61c7d749048fa6e3322258b4263463bfccefecb0dd731b6561cb617a1d9bb9 \
+    --hash=sha256:72e24c521fa2106f19623a3851e9f89ddfdeb9ac63871c7643790f872a305dfc \
+    --hash=sha256:7b97ae6ef5cba2e3bb14256625423413d5ce8d1abb91d4f29b6d1a081da765f8 \
+    --hash=sha256:961e886d8a3590fd2c723cf07be14e2a91cf53c25f02435c04d39e90780e3b53 \
+    --hash=sha256:96d8473848e984184b6728e2c9d391482008646276c3ff084a1bd89e15ff53a1 \
+    --hash=sha256:ae536da50c7ad1e002c3eee101871d93abdc90d9c5f651818450a0d3af718609 \
+    --hash=sha256:b0db0cecf396033abb4a93c95d1602f268b3a68bb0a9cc06a7cff587bb9a7292 \
+    --hash=sha256:cfee9164954c186b191b91d4193989ca994703b2fff406f71cf454a2d3c7327e \
+    --hash=sha256:e6347742ac8f35ded4a46ff835c60e68c22a536a8ae5c4422966d06946b6d4c6 \
+    --hash=sha256:f27d93f0139a3c056172ebb5d4f9056e770fdf0206c2f422ff2ebbad142e09ed \
+    --hash=sha256:f57b76e46a58b63d1c6375017f4564a28f19a5ca912691fd2e4261b3414b618d \
     # via paramiko, pypsrp
-docutils==0.14 \
-    --hash=sha256:02aec4bd92ab067f6ff27a38a38a41173bf01bed8f89157768c1573f53e474a6 \
-    --hash=sha256:51e64ef2ebfb29cae1faa133b3710143496eca21c530f3f71424d77687764274 \
-    --hash=sha256:7a4bd47eaf6596e1295ecb11361139febe29b084a87bf005bf899f9a42edc3c6 \
-    # via botocore
+docutils==0.15.2 \
+    --hash=sha256:6c4f696463b79f1fb8ba0c594b63840ebd41f059e92b31957c46b74a4599b6d0 \
+    --hash=sha256:9e4d7ecfc600058e07ba661411a2b7de2fd0fafa17d1a7f7361cd47b1175c827 \
+    --hash=sha256:a2aeea129088da402665e92e0b25b04b073c04b2dce4ab65caaa38b7ce2e1a99 \
+    # via botocore, readme-renderer
 idna==2.8 \
     --hash=sha256:c357b3f628cf53ae2c4c05627ecc484553142ca23264e593d327bcde5e9c3407 \
     --hash=sha256:ea8b7f6188e6fa117537c3df7da9fc686d485087abf6ac197f9c46432f7e4a3c \
@@ -108,20 +106,24 b' jmespath==0.9.4 \\'
     --hash=sha256:3720a4b1bd659dd2eecad0666459b9788813e032b83e7ba58578e48254e0a0e6 \
     --hash=sha256:bde2aef6f44302dfb30320115b17d030798de8c4110e28d5cf6cf91a7a31074c \
     # via boto3, botocore
-ntlm-auth==1.3.0 \
-    --hash=sha256:bb2fd03c665f0f62c5f65695b62dcdb07fb7a45df6ebc86c770be2054d6902dd \
-    --hash=sha256:ce5b4483ed761f341a538a426a71a52e5a9cf5fd834ebef1d2090f9eef14b3f8 \
+ntlm-auth==1.4.0 \
+    --hash=sha256:11f7a3cec38155b7cecdd9bbc8c37cd738d8012f0523b3f98d8caefe394feb97 \
+    --hash=sha256:350f2389c8ee5517f47db55a36ac2f8efc9742a60a678d6e2caa92385bdcaa9a \
     # via pypsrp
-paramiko==2.4.2 \
-    --hash=sha256:3c16b2bfb4c0d810b24c40155dbfd113c0521e7e6ee593d704e84b4c658a1f3b \
-    --hash=sha256:a8975a7df3560c9f1e2b43dc54ebd40fd00a7017392ca5445ce7df409f900fcb
-pyasn1==0.4.5 \
-    --hash=sha256:da2420fe13a9452d8ae97a0e478adde1dee153b11ba832a95b223a2ba01c10f7 \
-    --hash=sha256:da6b43a8c9ae93bc80e2739efb38cc776ba74a886e3e9318d65fe81a8b8a2c6e \
-    # via paramiko
+paramiko==2.6.0 \
+    --hash=sha256:99f0179bdc176281d21961a003ffdb2ec369daac1a1007241f53374e376576cf \
+    --hash=sha256:f4b2edfa0d226b70bd4ca31ea7e389325990283da23465d572ed1f70a7583041
+pkginfo==1.5.0.1 \
+    --hash=sha256:7424f2c8511c186cd5424bbf31045b77435b37a8d604990b79d4e70d741148bb \
+    --hash=sha256:a6d9e40ca61ad3ebd0b72fbadd4fba16e4c0e4df0428c041e01e06eb6ee71f32 \
+    # via twine
 pycparser==2.19 \
     --hash=sha256:a988718abfad80b6b157acce7bf130a30876d27603738ac39f140993246b25b3 \
     # via cffi
+pygments==2.4.2 \
+    --hash=sha256:71e430bc85c88a430f000ac1d9b331d2407f681d6f6aec95e8bcfbc3df5b0127 \
+    --hash=sha256:881c4c157e45f30af185c1ffe8d549d48ac9127433f2c380c24b84572ad66297 \
+    # via readme-renderer
 pynacl==1.3.0 \
     --hash=sha256:05c26f93964373fc0abe332676cb6735f0ecad27711035b9472751faa8521255 \
     --hash=sha256:0c6100edd16fefd1557da078c7a31e7b7d7a52ce39fdca2bec29d4f7b6e7600c \
@@ -143,26 +145,49 b' pynacl==1.3.0 \\'
     --hash=sha256:e2da3c13307eac601f3de04887624939aca8ee3c9488a0bb0eca4fb9401fc6b1 \
     --hash=sha256:f67814c38162f4deb31f68d590771a29d5ae3b1bd64b75cf232308e5c74777e0 \
     # via paramiko
-pypsrp==0.3.1 \
-    --hash=sha256:309853380fe086090a03cc6662a778ee69b1cae355ae4a932859034fd76e9d0b \
-    --hash=sha256:90f946254f547dc3493cea8493c819ab87e152a755797c93aa2668678ba8ae85
+pypsrp==0.4.0 \
+    --hash=sha256:64b5bdd725a9744c821483b05ecd266f6417f4c6e90ee961a08838480f7d025e \
+    --hash=sha256:f42919247fb80f7dc24c552560d7c24e754d15326030c9e3b7b94f51cfa4dc69
 python-dateutil==2.8.0 \
     --hash=sha256:7e6584c74aeed623791615e26efd690f29817a27c73085b78e4bad02493df2fb \
     --hash=sha256:c89805f6f4d64db21ed966fda138f8a5ed7a4fdbc1a8ee329ce1b74e3c74da9e \
     # via botocore
-requests==2.21.0 \
-    --hash=sha256:502a824f31acdacb3a35b6690b5fbf0bc41d63a24a45c4004352b0242707598e \
-    --hash=sha256:7bf2a778576d825600030a110f3c0e3e8edc51dfaafe1c146e39a2027784957b \
-    # via pypsrp
-s3transfer==0.2.0 \
-    --hash=sha256:7b9ad3213bff7d357f888e0fab5101b56fa1a0548ee77d121c3a3dbfbef4cb2e \
-    --hash=sha256:f23d5cb7d862b104401d9021fc82e5fa0e0cf57b7660a1331425aab0c691d021 \
+readme-renderer==24.0 \
+    --hash=sha256:bb16f55b259f27f75f640acf5e00cf897845a8b3e4731b5c1a436e4b8529202f \
+    --hash=sha256:c8532b79afc0375a85f10433eca157d6b50f7d6990f337fa498c96cd4bfc203d \
+    # via twine
+requests-toolbelt==0.9.1 \
+    --hash=sha256:380606e1d10dc85c3bd47bf5a6095f815ec007be7a8b69c878507068df059e6f \
+    --hash=sha256:968089d4584ad4ad7c171454f0a5c6dac23971e9472521ea3b6d49d610aa6fc0 \
+    # via twine
+requests==2.22.0 \
+    --hash=sha256:11e007a8a2aa0323f5a921e9e6a2d7e4e67d9877e85773fba9ba6419025cbeb4 \
+    --hash=sha256:9cf5292fcd0f598c671cfc1e0d7d1a7f13bb8085e9a590f48c010551dc6c4b31 \
+    # via pypsrp, requests-toolbelt, twine
+s3transfer==0.2.1 \
+    --hash=sha256:6efc926738a3cd576c2a79725fed9afde92378aa5c6a957e3af010cb019fac9d \
+    --hash=sha256:b780f2411b824cb541dbcd2c713d0cb61c7d1bcadae204cdddda2b35cef493ba \
     # via boto3
 six==1.12.0 \
     --hash=sha256:3350809f0555b11f552448330d0b52d5f24c91a322ea4a15ef22629740f3761c \
     --hash=sha256:d16a0141ec1a18405cd4ce8b4613101da75da0e9a7aec5bdd4fa804d0e0eba73 \
-    # via bcrypt, cryptography, pynacl, pypsrp, python-dateutil
-urllib3==1.24.2 \
-    --hash=sha256:4c291ca23bbb55c76518905869ef34bdd5f0e46af7afe6861e8375643ffee1a0 \
-    --hash=sha256:9a247273df709c4fedb38c711e44292304f73f39ab01beda9f6b9fc375669ac3 \
+    # via bcrypt, bleach, cryptography, pynacl, pypsrp, python-dateutil, readme-renderer
+tqdm==4.36.1 \
+    --hash=sha256:abc25d0ce2397d070ef07d8c7e706aede7920da163c64997585d42d3537ece3d \
+    --hash=sha256:dd3fcca8488bb1d416aa7469d2f277902f26260c45aa86b667b074cd44b3b115 \
+    # via twine
+twine==2.0.0 \
+    --hash=sha256:5319dd3e02ac73fcddcd94f035b9631589ab5d23e1f4699d57365199d85261e1 \
+    --hash=sha256:9fe7091715c7576df166df8ef6654e61bada39571783f2fd415bdcba867c6993
+urllib3==1.25.6 \
+    --hash=sha256:3de946ffbed6e6746608990594d08faac602528ac7015ac28d33cee6a45b7398 \
+    --hash=sha256:9a107b99a5393caf59c7aa3c1249c16e6879447533d0887f4336dde834c7be86 \
     # via botocore, requests
+webencodings==0.5.1 \
+    --hash=sha256:a0af1213f3c2226497a97e2b3aa01a7e4bee4f403f95be16fc9acd2947514a78 \
+    --hash=sha256:b36a1c245f2d304965eb4e0a82848379241dc04b865afcc4aab16748587e1923 \
+    # via bleach
+
+# WARNING: The following packages were not pinned, but pip requires them to be
+# pinned when the requirements file includes hashes. Consider using the --allow-unsafe flag.
+# setuptools==41.2.0        # via twine

contrib/automation/requirements.txt.in

@@ -1,3 +1,4 b''
 boto3
 paramiko
 pypsrp
+twine

contrib/bdiff-torture.py

@@ -6,17 +6,23 b' import sys'
 
 from mercurial import (
     mdiff,
+    pycompat,
 )
 
+
 def reducetest(a, b):
     tries = 0
     reductions = 0
     print("reducing...")
     while tries < 1000:
-        a2 = "\n".join(l for l in a.splitlines()
-                       if random.randint(0, 100) > 0) + "\n"
-        b2 = "\n".join(l for l in b.splitlines()
-                       if random.randint(0, 100) > 0) + "\n"
+        a2 = (
+            "\n".join(l for l in a.splitlines() if random.randint(0, 100) > 0)
+            + "\n"
+        )
+        b2 = (
+            "\n".join(l for l in b.splitlines() if random.randint(0, 100) > 0)
+            + "\n"
+        )
         if a2 == a and b2 == b:
             continue
         if a2 == b2:
@@ -31,8 +37,7 b' def reducetest(a, b):'
             a = a2
             b = b2
 
-    print("reduced:", reductions, len(a) + len(b),
-          repr(a), repr(b))
+    print("reduced:", reductions, len(a) + len(b), repr(a), repr(b))
     try:
         test1(a, b)
     except Exception as inst:
@@ -40,6 +45,7 b' def reducetest(a, b):'
 
     sys.exit(0)
 
+
 def test1(a, b):
     d = mdiff.textdiff(a, b)
     if not d:
@@ -48,23 +54,25 b' def test1(a, b):'
     if c != b:
         raise ValueError("bad")
 
+
 def testwrap(a, b):
     try:
         test1(a, b)
         return
     except Exception as inst:
-        pass
-    print("exception:", inst)
+        print("exception:", inst)
     reducetest(a, b)
 
+
 def test(a, b):
     testwrap(a, b)
     testwrap(b, a)
 
+
 def rndtest(size, noise):
     a = []
     src = "                aaaaaaaabbbbccd"
-    for x in xrange(size):
+    for x in pycompat.xrange(size):
         a.append(src[random.randint(0, len(src) - 1)])
 
     while True:
@@ -82,6 +90,7 b' def rndtest(size, noise):'
 
     test(a, b)
 
+
 maxvol = 10000
 startsize = 2
 while True:

contrib/benchmarks/__init__.py

@@ -44,15 +44,24 b' from mercurial import ('
     util,
 )
 
-basedir = os.path.abspath(os.path.join(os.path.dirname(__file__),
-                          os.path.pardir, os.path.pardir))
+basedir = os.path.abspath(
+    os.path.join(os.path.dirname(__file__), os.path.pardir, os.path.pardir)
+)
 reposdir = os.environ['REPOS_DIR']
-reposnames = [name for name in os.listdir(reposdir)
-              if os.path.isdir(os.path.join(reposdir, name, ".hg"))]
+reposnames = [
+    name
+    for name in os.listdir(reposdir)
+    if os.path.isdir(os.path.join(reposdir, name, ".hg"))
+]
 if not reposnames:
     raise ValueError("No repositories found in $REPO_DIR")
-outputre = re.compile((r'! wall (\d+.\d+) comb \d+.\d+ user \d+.\d+ sys '
-                       r'\d+.\d+ \(best of \d+\)'))
+outputre = re.compile(
+    (
+        r'! wall (\d+.\d+) comb \d+.\d+ user \d+.\d+ sys '
+        r'\d+.\d+ \(best of \d+\)'
+    )
+)
+
 
 def runperfcommand(reponame, command, *args, **kwargs):
     os.environ["HGRCPATH"] = os.environ.get("ASVHGRCPATH", "")
@@ -63,8 +72,9 b' def runperfcommand(reponame, command, *a'
     else:
         ui = uimod.ui()
     repo = hg.repository(ui, os.path.join(reposdir, reponame))
-    perfext = extensions.load(ui, 'perfext',
-                              os.path.join(basedir, 'contrib', 'perf.py'))
+    perfext = extensions.load(
+        ui, 'perfext', os.path.join(basedir, 'contrib', 'perf.py')
+    )
     cmd = getattr(perfext, command)
     ui.pushbuffer()
     cmd(ui, repo, *args, **kwargs)
@@ -74,6 +84,7 b' def runperfcommand(reponame, command, *a'
         raise ValueError("Invalid output {0}".format(output))
     return float(match.group(1))
 
+
 def perfbench(repos=reposnames, name=None, params=None):
     """decorator to declare ASV benchmark based on contrib/perf.py extension
 
@@ -104,10 +115,12 b' def perfbench(repos=reposnames, name=Non'
         def wrapped(repo, *args):
             def perf(command, *a, **kw):
                 return runperfcommand(repo, command, *a, **kw)
+
             return func(perf, *args)
 
         wrapped.params = [p[1] for p in params]
         wrapped.param_names = [p[0] for p in params]
         wrapped.pretty_name = name
         return wrapped
+
     return decorator

contrib/benchmarks/perf.py

@@ -9,18 +9,22 b' from __future__ import absolute_import'
 
 from . import perfbench
 
+
 @perfbench()
 def track_tags(perf):
     return perf("perftags")
 
+
 @perfbench()
 def track_status(perf):
     return perf("perfstatus", unknown=False)
 
+
 @perfbench(params=[('rev', ['1000', '10000', 'tip'])])
 def track_manifest(perf, rev):
     return perf("perfmanifest", rev)
 
+
 @perfbench()
 def track_heads(perf):
     return perf("perfheads")

contrib/benchmarks/revset.py

@@ -18,15 +18,16 b' import sys'
 
 from . import basedir, perfbench
 
+
 def createrevsetbenchmark(baseset, variants=None):
     if variants is None:
         # Default variants
-        variants = ["plain", "first", "last", "sort", "sort+first",
-                    "sort+last"]
-    fname = "track_" + "_".join("".join([
-        c if c in string.digits + string.letters else " "
-        for c in baseset
-    ]).split())
+        variants = ["plain", "first", "last", "sort", "sort+first", "sort+last"]
+    fname = "track_" + "_".join(
+        "".join(
+            [c if c in string.digits + string.letters else " " for c in baseset]
+        ).split()
+    )
 
     def wrap(fname, baseset):
         @perfbench(name=baseset, params=[("variant", variants)])
@@ -36,18 +37,21 b' def createrevsetbenchmark(baseset, varia'
                 for var in variant.split("+"):
                     revset = "%s(%s)" % (var, revset)
             return perf("perfrevset", revset)
+
         f.__name__ = fname
         return f
+
     return wrap(fname, baseset)
 
+
 def initializerevsetbenchmarks():
     mod = sys.modules[__name__]
-    with open(os.path.join(basedir, 'contrib', 'base-revsets.txt'),
-              'rb') as fh:
+    with open(os.path.join(basedir, 'contrib', 'base-revsets.txt'), 'rb') as fh:
         for line in fh:
             baseset = line.strip()
             if baseset and not baseset.startswith('#'):
                 func = createrevsetbenchmark(baseset)
                 setattr(mod, func.__name__, func)
 
+
 initializerevsetbenchmarks()

contrib/byteify-strings.py

@@ -18,10 +18,13 b' import tempfile'
 import token
 import tokenize
 
+
 def adjusttokenpos(t, ofs):
     """Adjust start/end column of the given token"""
-    return t._replace(start=(t.start[0], t.start[1] + ofs),
-                      end=(t.end[0], t.end[1] + ofs))
+    return t._replace(
+        start=(t.start[0], t.start[1] + ofs), end=(t.end[0], t.end[1] + ofs)
+    )
+
 
 def replacetokens(tokens, opts):
     """Transform a stream of tokens from raw to Python 3.
@@ -78,23 +81,68 b' def replacetokens(tokens, opts):'
         already been done.
 
         """
-        st = tokens[j]
-        if st.type == token.STRING and st.string.startswith(("'", '"')):
-            sysstrtokens.add(st)
+        k = j
+        currtoken = tokens[k]
+        while currtoken.type in (token.STRING, token.NEWLINE, tokenize.NL):
+            k += 1
+            if currtoken.type == token.STRING and currtoken.string.startswith(
+                ("'", '"')
+            ):
+                sysstrtokens.add(currtoken)
+            try:
+                currtoken = tokens[k]
+            except IndexError:
+                break
+
+    def _isitemaccess(j):
+        """Assert the next tokens form an item access on `tokens[j]` and that
+        `tokens[j]` is a name.
+        """
+        try:
+            return (
+                tokens[j].type == token.NAME
+                and _isop(j + 1, '[')
+                and tokens[j + 2].type == token.STRING
+                and _isop(j + 3, ']')
+            )
+        except IndexError:
+            return False
+
+    def _ismethodcall(j, *methodnames):
+        """Assert the next tokens form a call to `methodname` with a string
+        as first argument on `tokens[j]` and that `tokens[j]` is a name.
+        """
+        try:
+            return (
+                tokens[j].type == token.NAME
+                and _isop(j + 1, '.')
+                and tokens[j + 2].type == token.NAME
+                and tokens[j + 2].string in methodnames
+                and _isop(j + 3, '(')
+                and tokens[j + 4].type == token.STRING
+            )
+        except IndexError:
+            return False
 
     coldelta = 0  # column increment for new opening parens
     coloffset = -1  # column offset for the current line (-1: TBD)
-    parens = [(0, 0, 0)]  # stack of (line, end-column, column-offset)
+    parens = [(0, 0, 0, -1)]  # stack of (line, end-column, column-offset, type)
+    ignorenextline = False  # don't transform the next line
+    insideignoreblock = False  # don't transform until turned off
     for i, t in enumerate(tokens):
         # Compute the column offset for the current line, such that
         # the current line will be aligned to the last opening paren
         # as before.
         if coloffset < 0:
-            if t.start[1] == parens[-1][1]:
-                coloffset = parens[-1][2]
-            elif t.start[1] + 1 == parens[-1][1]:
+            lastparen = parens[-1]
+            if t.start[1] == lastparen[1]:
+                coloffset = lastparen[2]
+            elif t.start[1] + 1 == lastparen[1] and lastparen[3] not in (
+                token.NEWLINE,
+                tokenize.NL,
+            ):
                 # fix misaligned indent of s/util.Abort/error.Abort/
-                coloffset = parens[-1][2] + (parens[-1][1] - t.start[1])
+                coloffset = lastparen[2] + (lastparen[1] - t.start[1])
             else:
                 coloffset = 0
 
@@ -103,11 +151,26 b' def replacetokens(tokens, opts):'
             yield adjusttokenpos(t, coloffset)
             coldelta = 0
             coloffset = -1
+            if not insideignoreblock:
+                ignorenextline = (
+                    tokens[i - 1].type == token.COMMENT
+                    and tokens[i - 1].string == "# no-py3-transform"
+                )
+            continue
+
+        if t.type == token.COMMENT:
+            if t.string == "# py3-transform: off":
+                insideignoreblock = True
+            if t.string == "# py3-transform: on":
+                insideignoreblock = False
+
+        if ignorenextline or insideignoreblock:
+            yield adjusttokenpos(t, coloffset)
             continue
 
         # Remember the last paren position.
         if _isop(i, '(', '[', '{'):
-            parens.append(t.end + (coloffset + coldelta,))
+            parens.append(t.end + (coloffset + coldelta, tokens[i + 1].type))
         elif _isop(i, ')', ']', '}'):
             parens.pop()
 
@@ -129,8 +192,10 b' def replacetokens(tokens, opts):'
             # components touching docstrings need to handle unicode,
             # unfortunately.
             if s[0:3] in ("'''", '"""'):
-                yield adjusttokenpos(t, coloffset)
-                continue
+                # If it's assigned to something, it's not a docstring
+                if not _isop(i - 1, '='):
+                    yield adjusttokenpos(t, coloffset)
+                    continue
 
             # If the first character isn't a quote, it is likely a string
             # prefixing character (such as 'b', 'u', or 'r'. Ignore.
@@ -139,8 +204,7 b' def replacetokens(tokens, opts):'
                 continue
 
             # String literal. Prefix to make a b'' string.
-            yield adjusttokenpos(t._replace(string='b%s' % t.string),
-                                 coloffset)
+            yield adjusttokenpos(t._replace(string='b%s' % t.string), coloffset)
             coldelta += 1
             continue
 
@@ -149,8 +213,15 b' def replacetokens(tokens, opts):'
             fn = t.string
 
             # *attr() builtins don't accept byte strings to 2nd argument.
-            if (fn in ('getattr', 'setattr', 'hasattr', 'safehasattr') and
-                    not _isop(i - 1, '.')):
+            if fn in (
+                'getattr',
+                'setattr',
+                'hasattr',
+                'safehasattr',
+                'wrapfunction',
+                'wrapclass',
+                'addattr',
+            ) and (opts['allow-attr-methods'] or not _isop(i - 1, '.')):
                 arg1idx = _findargnofcall(1)
                 if arg1idx is not None:
                     _ensuresysstr(arg1idx)
@@ -169,19 +240,30 b' def replacetokens(tokens, opts):'
                 yield adjusttokenpos(t._replace(string=fn[4:]), coloffset)
                 continue
 
+        if t.type == token.NAME and t.string in opts['treat-as-kwargs']:
+            if _isitemaccess(i):
+                _ensuresysstr(i + 2)
+            if _ismethodcall(i, 'get', 'pop', 'setdefault', 'popitem'):
+                _ensuresysstr(i + 4)
+
         # Looks like "if __name__ == '__main__'".
-        if (t.type == token.NAME and t.string == '__name__'
-            and _isop(i + 1, '==')):
+        if (
+            t.type == token.NAME
+            and t.string == '__name__'
+            and _isop(i + 1, '==')
+        ):
             _ensuresysstr(i + 2)
 
         # Emit unmodified token.
         yield adjusttokenpos(t, coloffset)
 
+
 def process(fin, fout, opts):
     tokens = tokenize.tokenize(fin.readline)
     tokens = replacetokens(list(tokens), opts)
     fout.write(tokenize.untokenize(tokens))
 
+
 def tryunlink(fname):
     try:
         os.unlink(fname)
@@ -189,12 +271,14 b' def tryunlink(fname):'
         if err.errno != errno.ENOENT:
             raise
 
+
 @contextlib.contextmanager
 def editinplace(fname):
     n = os.path.basename(fname)
     d = os.path.dirname(fname)
-    fp = tempfile.NamedTemporaryFile(prefix='.%s-' % n, suffix='~', dir=d,
-                                     delete=False)
+    fp = tempfile.NamedTemporaryFile(
+        prefix='.%s-' % n, suffix='~', dir=d, delete=False
+    )
     try:
         yield fp
         fp.close()
@@ -205,16 +289,43 b' def editinplace(fname):'
         fp.close()
         tryunlink(fp.name)
 
+
 def main():
     ap = argparse.ArgumentParser()
-    ap.add_argument('-i', '--inplace', action='store_true', default=False,
-                    help='edit files in place')
-    ap.add_argument('--dictiter', action='store_true', default=False,
-                    help='rewrite iteritems() and itervalues()'),
+    ap.add_argument(
+        '--version', action='version', version='Byteify strings 1.0'
+    )
+    ap.add_argument(
+        '-i',
+        '--inplace',
+        action='store_true',
+        default=False,
+        help='edit files in place',
+    )
+    ap.add_argument(
+        '--dictiter',
+        action='store_true',
+        default=False,
+        help='rewrite iteritems() and itervalues()',
+    ),
+    ap.add_argument(
+        '--allow-attr-methods',
+        action='store_true',
+        default=False,
+        help='also handle attr*() when they are methods',
+    ),
+    ap.add_argument(
+        '--treat-as-kwargs',
+        nargs="+",
+        default=[],
+        help="ignore kwargs-like objects",
+    ),
     ap.add_argument('files', metavar='FILE', nargs='+', help='source file')
     args = ap.parse_args()
     opts = {
         'dictiter': args.dictiter,
+        'treat-as-kwargs': set(args.treat_as_kwargs),
+        'allow-attr-methods': args.allow_attr_methods,
     }
     for fname in args.files:
         if args.inplace:
@@ -226,6 +337,7 b' def main():'
                 fout = sys.stdout.buffer
                 process(fin, fout, opts)
 
+
 if __name__ == '__main__':
     if sys.version_info.major < 3:
         print('This script must be run under Python 3.')

contrib/casesmash.py

@@ -1,12 +1,12 b''
 from __future__ import absolute_import
 import __builtin__
 import os
-from mercurial import (
-    util,
-)
+from mercurial import util
+
 
 def lowerwrap(scope, funcname):
     f = getattr(scope, funcname)
+
     def wrap(fname, *args, **kwargs):
         d, base = os.path.split(fname)
         try:
@@ -19,11 +19,14 b' def lowerwrap(scope, funcname):'
             if fn.lower() == base.lower():
                 return f(os.path.join(d, fn), *args, **kwargs)
         return f(fname, *args, **kwargs)
+
     scope.__dict__[funcname] = wrap
 
+
 def normcase(path):
     return path.lower()
 
+
 os.path.normcase = normcase
 
 for f in 'file open'.split():

contrib/catapipe.py

@@ -53,15 +53,28 b' import timeit'
 # Python version and OS
 timer = timeit.default_timer
 
+
 def main():
     parser = argparse.ArgumentParser()
-    parser.add_argument('pipe', type=str, nargs=1,
-                        help='Path of named pipe to create and listen on.')
-    parser.add_argument('output', default='trace.json', type=str, nargs='?',
-                        help='Path of json file to create where the traces '
-                             'will be stored.')
-    parser.add_argument('--debug', default=False, action='store_true',
-                        help='Print useful debug messages')
+    parser.add_argument(
+        'pipe',
+        type=str,
+        nargs=1,
+        help='Path of named pipe to create and listen on.',
+    )
+    parser.add_argument(
+        'output',
+        default='trace.json',
+        type=str,
+        nargs='?',
+        help='Path of json file to create where the traces ' 'will be stored.',
+    )
+    parser.add_argument(
+        '--debug',
+        default=False,
+        action='store_true',
+        help='Print useful debug messages',
+    )
     args = parser.parse_args()
     fn = args.pipe[0]
     os.mkfifo(fn)
@@ -86,19 +99,23 b' def main():'
                     payload_args = {}
                 pid = _threadmap[session]
                 ts_micros = (now - start) * 1000000
-                out.write(json.dumps(
-                    {
-                        "name": label,
-                        "cat": "misc",
-                        "ph": _TYPEMAP[verb],
-                        "ts": ts_micros,
-                        "pid": pid,
-                        "tid": 1,
-                        "args": payload_args,
-                    }))
+                out.write(
+                    json.dumps(
+                        {
+                            "name": label,
+                            "cat": "misc",
+                            "ph": _TYPEMAP[verb],
+                            "ts": ts_micros,
+                            "pid": pid,
+                            "tid": 1,
+                            "args": payload_args,
+                        }
+                    )
+                )
                 out.write(',\n')
     finally:
         os.unlink(fn)
 
+
 if __name__ == '__main__':
     main()

contrib/check-code.py

@@ -26,11 +26,15 b' import optparse'
 import os
 import re
 import sys
+
 if sys.version_info[0] < 3:
     opentext = open
 else:
+
     def opentext(f):
         return open(f, encoding='latin1')
+
+
 try:
     xrange
 except NameError:
@@ -42,6 +46,7 b' except ImportError:'
 
 import testparseutil
 
+
 def compilere(pat, multiline=False):
     if multiline:
         pat = '(?m)' + pat
@@ -52,10 +57,22 b' def compilere(pat, multiline=False):'
             pass
     return re.compile(pat)
 
+
 # check "rules depending on implementation of repquote()" in each
 # patterns (especially pypats), before changing around repquote()
-_repquotefixedmap = {' ': ' ', '\n': '\n', '.': 'p', ':': 'q',
-                     '%': '%', '\\': 'b', '*': 'A', '+': 'P', '-': 'M'}
+_repquotefixedmap = {
+    ' ': ' ',
+    '\n': '\n',
+    '.': 'p',
+    ':': 'q',
+    '%': '%',
+    '\\': 'b',
+    '*': 'A',
+    '+': 'P',
+    '-': 'M',
+}
+
+
 def _repquoteencodechr(i):
     if i > 255:
         return 'u'
@@ -67,13 +84,17 b' def _repquoteencodechr(i):'
     if c.isdigit():
         return 'n'
     return 'o'
+
+
 _repquotett = ''.join(_repquoteencodechr(i) for i in xrange(256))
 
+
 def repquote(m):
     t = m.group('text')
     t = t.translate(_repquotett)
     return m.group('quote') + t + m.group('quote')
 
+
 def reppython(m):
     comment = m.group('comment')
     if comment:
@@ -81,87 +102,103 b' def reppython(m):'
         return "#" * l + comment[l:]
     return repquote(m)
 
+
 def repcomment(m):
     return m.group(1) + "#" * len(m.group(2))
 
+
 def repccomment(m):
     t = re.sub(r"((?<=\n) )|\S", "x", m.group(2))
     return m.group(1) + t + "*/"
 
+
 def repcallspaces(m):
     t = re.sub(r"\n\s+", "\n", m.group(2))
     return m.group(1) + t
 
+
 def repinclude(m):
     return m.group(1) + "<foo>"
 
+
 def rephere(m):
     t = re.sub(r"\S", "x", m.group(2))
     return m.group(1) + t
 
 
 testpats = [
-  [
-    (r'\b(push|pop)d\b', "don't use 'pushd' or 'popd', use 'cd'"),
-    (r'\W\$?\(\([^\)\n]*\)\)', "don't use (()) or $(()), use 'expr'"),
-    (r'grep.*-q', "don't use 'grep -q', redirect to /dev/null"),
-    (r'(?<!hg )grep.* -a', "don't use 'grep -a', use in-line python"),
-    (r'sed.*-i', "don't use 'sed -i', use a temporary file"),
-    (r'\becho\b.*\\n', "don't use 'echo \\n', use printf"),
-    (r'echo -n', "don't use 'echo -n', use printf"),
-    (r'(^|\|\s*)\bwc\b[^|]*$\n(?!.*\(re\))', "filter wc output"),
-    (r'head -c', "don't use 'head -c', use 'dd'"),
-    (r'tail -n', "don't use the '-n' option to tail, just use '-<num>'"),
-    (r'sha1sum', "don't use sha1sum, use $TESTDIR/md5sum.py"),
-    (r'\bls\b.*-\w*R', "don't use 'ls -R', use 'find'"),
-    (r'printf.*[^\\]\\([1-9]|0\d)', r"don't use 'printf \NNN', use Python"),
-    (r'printf.*[^\\]\\x', "don't use printf \\x, use Python"),
-    (r'\$\(.*\)', "don't use $(expr), use `expr`"),
-    (r'rm -rf \*', "don't use naked rm -rf, target a directory"),
-    (r'\[[^\]]+==', '[ foo == bar ] is a bashism, use [ foo = bar ] instead'),
-    (r'(^|\|\s*)grep (-\w\s+)*[^|]*[(|]\w',
-     "use egrep for extended grep syntax"),
-    (r'(^|\|\s*)e?grep .*\\S', "don't use \\S in regular expression"),
-    (r'(?<!!)/bin/', "don't use explicit paths for tools"),
-    (r'#!.*/bash', "don't use bash in shebang, use sh"),
-    (r'[^\n]\Z', "no trailing newline"),
-    (r'export .*=', "don't export and assign at once"),
-    (r'^source\b', "don't use 'source', use '.'"),
-    (r'touch -d', "don't use 'touch -d', use 'touch -t' instead"),
-    (r'\bls +[^|\n-]+ +-', "options to 'ls' must come before filenames"),
-    (r'[^>\n]>\s*\$HGRCPATH', "don't overwrite $HGRCPATH, append to it"),
-    (r'^stop\(\)', "don't use 'stop' as a shell function name"),
-    (r'(\[|\btest\b).*-e ', "don't use 'test -e', use 'test -f'"),
-    (r'\[\[\s+[^\]]*\]\]', "don't use '[[ ]]', use '[ ]'"),
-    (r'^alias\b.*=', "don't use alias, use a function"),
-    (r'if\s*!', "don't use '!' to negate exit status"),
-    (r'/dev/u?random', "don't use entropy, use /dev/zero"),
-    (r'do\s*true;\s*done', "don't use true as loop body, use sleep 0"),
-    (r'sed (-e )?\'(\d+|/[^/]*/)i(?!\\\n)',
-     "put a backslash-escaped newline after sed 'i' command"),
-    (r'^diff *-\w*[uU].*$\n(^  \$ |^$)', "prefix diff -u/-U with cmp"),
-    (r'^\s+(if)? diff *-\w*[uU]', "prefix diff -u/-U with cmp"),
-    (r'[\s="`\']python\s(?!bindings)', "don't use 'python', use '$PYTHON'"),
-    (r'seq ', "don't use 'seq', use $TESTDIR/seq.py"),
-    (r'\butil\.Abort\b', "directly use error.Abort"),
-    (r'\|&', "don't use |&, use 2>&1"),
-    (r'\w =  +\w', "only one space after = allowed"),
-    (r'\bsed\b.*[^\\]\\n', "don't use 'sed ... \\n', use a \\ and a newline"),
-    (r'env.*-u', "don't use 'env -u VAR', use 'unset VAR'"),
-    (r'cp.* -r ', "don't use 'cp -r', use 'cp -R'"),
-    (r'grep.* -[ABC]', "don't use grep's context flags"),
-    (r'find.*-printf',
-     "don't use 'find -printf', it doesn't exist on BSD find(1)"),
-    (r'\$RANDOM ', "don't use bash-only $RANDOM to generate random values"),
-  ],
-  # warnings
-  [
-    (r'^function', "don't use 'function', use old style"),
-    (r'^diff.*-\w*N', "don't use 'diff -N'"),
-    (r'\$PWD|\${PWD}', "don't use $PWD, use `pwd`"),
-    (r'^([^"\'\n]|("[^"\n]*")|(\'[^\'\n]*\'))*\^', "^ must be quoted"),
-    (r'kill (`|\$\()', "don't use kill, use killdaemons.py")
-  ]
+    [
+        (r'\b(push|pop)d\b', "don't use 'pushd' or 'popd', use 'cd'"),
+        (r'\W\$?\(\([^\)\n]*\)\)', "don't use (()) or $(()), use 'expr'"),
+        (r'grep.*-q', "don't use 'grep -q', redirect to /dev/null"),
+        (r'(?<!hg )grep.* -a', "don't use 'grep -a', use in-line python"),
+        (r'sed.*-i', "don't use 'sed -i', use a temporary file"),
+        (r'\becho\b.*\\n', "don't use 'echo \\n', use printf"),
+        (r'echo -n', "don't use 'echo -n', use printf"),
+        (r'(^|\|\s*)\bwc\b[^|]*$\n(?!.*\(re\))', "filter wc output"),
+        (r'head -c', "don't use 'head -c', use 'dd'"),
+        (r'tail -n', "don't use the '-n' option to tail, just use '-<num>'"),
+        (r'sha1sum', "don't use sha1sum, use $TESTDIR/md5sum.py"),
+        (r'\bls\b.*-\w*R', "don't use 'ls -R', use 'find'"),
+        (r'printf.*[^\\]\\([1-9]|0\d)', r"don't use 'printf \NNN', use Python"),
+        (r'printf.*[^\\]\\x', "don't use printf \\x, use Python"),
+        (r'rm -rf \*', "don't use naked rm -rf, target a directory"),
+        (
+            r'\[[^\]]+==',
+            '[ foo == bar ] is a bashism, use [ foo = bar ] instead',
+        ),
+        (
+            r'(^|\|\s*)grep (-\w\s+)*[^|]*[(|]\w',
+            "use egrep for extended grep syntax",
+        ),
+        (r'(^|\|\s*)e?grep .*\\S', "don't use \\S in regular expression"),
+        (r'(?<!!)/bin/', "don't use explicit paths for tools"),
+        (r'#!.*/bash', "don't use bash in shebang, use sh"),
+        (r'[^\n]\Z', "no trailing newline"),
+        (r'export .*=', "don't export and assign at once"),
+        (r'^source\b', "don't use 'source', use '.'"),
+        (r'touch -d', "don't use 'touch -d', use 'touch -t' instead"),
+        (r'\bls +[^|\n-]+ +-', "options to 'ls' must come before filenames"),
+        (r'[^>\n]>\s*\$HGRCPATH', "don't overwrite $HGRCPATH, append to it"),
+        (r'^stop\(\)', "don't use 'stop' as a shell function name"),
+        (r'(\[|\btest\b).*-e ', "don't use 'test -e', use 'test -f'"),
+        (r'\[\[\s+[^\]]*\]\]', "don't use '[[ ]]', use '[ ]'"),
+        (r'^alias\b.*=', "don't use alias, use a function"),
+        (r'if\s*!', "don't use '!' to negate exit status"),
+        (r'/dev/u?random', "don't use entropy, use /dev/zero"),
+        (r'do\s*true;\s*done', "don't use true as loop body, use sleep 0"),
+        (
+            r'sed (-e )?\'(\d+|/[^/]*/)i(?!\\\n)',
+            "put a backslash-escaped newline after sed 'i' command",
+        ),
+        (r'^diff *-\w*[uU].*$\n(^  \$ |^$)', "prefix diff -u/-U with cmp"),
+        (r'^\s+(if)? diff *-\w*[uU]', "prefix diff -u/-U with cmp"),
+        (r'[\s="`\']python\s(?!bindings)', "don't use 'python', use '$PYTHON'"),
+        (r'seq ', "don't use 'seq', use $TESTDIR/seq.py"),
+        (r'\butil\.Abort\b', "directly use error.Abort"),
+        (r'\|&', "don't use |&, use 2>&1"),
+        (r'\w =  +\w', "only one space after = allowed"),
+        (
+            r'\bsed\b.*[^\\]\\n',
+            "don't use 'sed ... \\n', use a \\ and a newline",
+        ),
+        (r'env.*-u', "don't use 'env -u VAR', use 'unset VAR'"),
+        (r'cp.* -r ', "don't use 'cp -r', use 'cp -R'"),
+        (r'grep.* -[ABC]', "don't use grep's context flags"),
+        (
+            r'find.*-printf',
+            "don't use 'find -printf', it doesn't exist on BSD find(1)",
+        ),
+        (r'\$RANDOM ', "don't use bash-only $RANDOM to generate random values"),
+    ],
+    # warnings
+    [
+        (r'^function', "don't use 'function', use old style"),
+        (r'^diff.*-\w*N', "don't use 'diff -N'"),
+        (r'\$PWD|\${PWD}', "don't use $PWD, use `pwd`"),
+        (r'^([^"\'\n]|("[^"\n]*")|(\'[^\'\n]*\'))*\^', "^ must be quoted"),
+        (r'kill (`|\$\()', "don't use kill, use killdaemons.py"),
+    ],
 ]
 
 testfilters = [
@@ -171,45 +208,72 b' testfilters = ['
 
 uprefix = r"^  \$ "
 utestpats = [
-  [
-    (r'^(\S.*||  [$>] \S.*)[ \t]\n', "trailing whitespace on non-output"),
-    (uprefix + r'.*\|\s*sed[^|>\n]*\n',
-     "use regex test output patterns instead of sed"),
-    (uprefix + r'(true|exit 0)', "explicit zero exit unnecessary"),
-    (uprefix + r'.*(?<!\[)\$\?', "explicit exit code checks unnecessary"),
-    (uprefix + r'.*\|\| echo.*(fail|error)',
-     "explicit exit code checks unnecessary"),
-    (uprefix + r'set -e', "don't use set -e"),
-    (uprefix + r'(\s|fi\b|done\b)', "use > for continued lines"),
-    (uprefix + r'.*:\.\S*/', "x:.y in a path does not work on msys, rewrite "
-     "as x://.y, or see `hg log -k msys` for alternatives", r'-\S+:\.|' #-Rxxx
-     '# no-msys'), # in test-pull.t which is skipped on windows
-    (r'^  [^$>].*27\.0\.0\.1',
-     'use $LOCALIP not an explicit loopback address'),
-    (r'^  (?![>$] ).*\$LOCALIP.*[^)]$',
-     'mark $LOCALIP output lines with (glob) to help tests in BSD jails'),
-    (r'^  (cat|find): .*: \$ENOENT\$',
-     'use test -f to test for file existence'),
-    (r'^  diff -[^ -]*p',
-     "don't use (external) diff with -p for portability"),
-    (r' readlink ', 'use readlink.py instead of readlink'),
-    (r'^  [-+][-+][-+] .* [-+]0000 \(glob\)',
-     "glob timezone field in diff output for portability"),
-    (r'^  @@ -[0-9]+ [+][0-9]+,[0-9]+ @@',
-     "use '@@ -N* +N,n @@ (glob)' style chunk header for portability"),
-    (r'^  @@ -[0-9]+,[0-9]+ [+][0-9]+ @@',
-     "use '@@ -N,n +N* @@ (glob)' style chunk header for portability"),
-    (r'^  @@ -[0-9]+ [+][0-9]+ @@',
-     "use '@@ -N* +N* @@ (glob)' style chunk header for portability"),
-    (uprefix + r'hg( +-[^ ]+( +[^ ]+)?)* +extdiff'
-     r'( +(-[^ po-]+|--(?!program|option)[^ ]+|[^-][^ ]*))*$',
-     "use $RUNTESTDIR/pdiff via extdiff (or -o/-p for false-positives)"),
-  ],
-  # warnings
-  [
-    (r'^  (?!.*\$LOCALIP)[^*?/\n]* \(glob\)$',
-     "glob match with no glob string (?, *, /, and $LOCALIP)"),
-  ]
+    [
+        (r'^(\S.*||  [$>] \S.*)[ \t]\n', "trailing whitespace on non-output"),
+        (
+            uprefix + r'.*\|\s*sed[^|>\n]*\n',
+            "use regex test output patterns instead of sed",
+        ),
+        (uprefix + r'(true|exit 0)', "explicit zero exit unnecessary"),
+        (uprefix + r'.*(?<!\[)\$\?', "explicit exit code checks unnecessary"),
+        (
+            uprefix + r'.*\|\| echo.*(fail|error)',
+            "explicit exit code checks unnecessary",
+        ),
+        (uprefix + r'set -e', "don't use set -e"),
+        (uprefix + r'(\s|fi\b|done\b)', "use > for continued lines"),
+        (
+            uprefix + r'.*:\.\S*/',
+            "x:.y in a path does not work on msys, rewrite "
+            "as x://.y, or see `hg log -k msys` for alternatives",
+            r'-\S+:\.|' '# no-msys',  # -Rxxx
+        ),  # in test-pull.t which is skipped on windows
+        (
+            r'^  [^$>].*27\.0\.0\.1',
+            'use $LOCALIP not an explicit loopback address',
+        ),
+        (
+            r'^  (?![>$] ).*\$LOCALIP.*[^)]$',
+            'mark $LOCALIP output lines with (glob) to help tests in BSD jails',
+        ),
+        (
+            r'^  (cat|find): .*: \$ENOENT\$',
+            'use test -f to test for file existence',
+        ),
+        (
+            r'^  diff -[^ -]*p',
+            "don't use (external) diff with -p for portability",
+        ),
+        (r' readlink ', 'use readlink.py instead of readlink'),
+        (
+            r'^  [-+][-+][-+] .* [-+]0000 \(glob\)',
+            "glob timezone field in diff output for portability",
+        ),
+        (
+            r'^  @@ -[0-9]+ [+][0-9]+,[0-9]+ @@',
+            "use '@@ -N* +N,n @@ (glob)' style chunk header for portability",
+        ),
+        (
+            r'^  @@ -[0-9]+,[0-9]+ [+][0-9]+ @@',
+            "use '@@ -N,n +N* @@ (glob)' style chunk header for portability",
+        ),
+        (
+            r'^  @@ -[0-9]+ [+][0-9]+ @@',
+            "use '@@ -N* +N* @@ (glob)' style chunk header for portability",
+        ),
+        (
+            uprefix + r'hg( +-[^ ]+( +[^ ]+)?)* +extdiff'
+            r'( +(-[^ po-]+|--(?!program|option)[^ ]+|[^-][^ ]*))*$',
+            "use $RUNTESTDIR/pdiff via extdiff (or -o/-p for false-positives)",
+        ),
+    ],
+    # warnings
+    [
+        (
+            r'^  (?!.*\$LOCALIP)[^*?/\n]* \(glob\)$',
+            "glob match with no glob string (?, *, /, and $LOCALIP)",
+        ),
+    ],
 ]
 
 # transform plain test rules to unified test's
@@ -235,157 +299,214 b' utestfilters = ['
 
 # common patterns to check *.py
 commonpypats = [
-  [
-    (r'\\$', 'Use () to wrap long lines in Python, not \\'),
-    (r'^\s*def\s*\w+\s*\(.*,\s*\(',
-     "tuple parameter unpacking not available in Python 3+"),
-    (r'lambda\s*\(.*,.*\)',
-     "tuple parameter unpacking not available in Python 3+"),
-    (r'(?<!def)\s+(cmp)\(', "cmp is not available in Python 3+"),
-    (r'(?<!\.)\breduce\s*\(.*', "reduce is not available in Python 3+"),
-    (r'\bdict\(.*=', 'dict() is different in Py2 and 3 and is slower than {}',
-     'dict-from-generator'),
-    (r'\.has_key\b', "dict.has_key is not available in Python 3+"),
-    (r'\s<>\s', '<> operator is not available in Python 3+, use !='),
-    (r'^\s*\t', "don't use tabs"),
-    (r'\S;\s*\n', "semicolon"),
-    (r'[^_]_\([ \t\n]*(?:"[^"]+"[ \t\n+]*)+%', "don't use % inside _()"),
-    (r"[^_]_\([ \t\n]*(?:'[^']+'[ \t\n+]*)+%", "don't use % inside _()"),
-    (r'(\w|\)),\w', "missing whitespace after ,"),
-    (r'(\w|\))[+/*\-<>]\w', "missing whitespace in expression"),
-    (r'^\s+(\w|\.)+=\w[^,()\n]*$', "missing whitespace in assignment"),
-    (r'\w\s=\s\s+\w', "gratuitous whitespace after ="),
-    ((
-        # a line ending with a colon, potentially with trailing comments
-        r':([ \t]*#[^\n]*)?\n'
-        # one that is not a pass and not only a comment
-        r'(?P<indent>[ \t]+)[^#][^\n]+\n'
-        # more lines at the same indent level
-        r'((?P=indent)[^\n]+\n)*'
-        # a pass at the same indent level, which is bogus
-        r'(?P=indent)pass[ \t\n#]'
-      ), 'omit superfluous pass'),
-    (r'[^\n]\Z', "no trailing newline"),
-    (r'(\S[ \t]+|^[ \t]+)\n', "trailing whitespace"),
-#    (r'^\s+[^_ \n][^_. \n]+_[^_\n]+\s*=',
-#     "don't use underbars in identifiers"),
-    (r'^\s+(self\.)?[A-Za-z][a-z0-9]+[A-Z]\w* = ',
-     "don't use camelcase in identifiers", r'#.*camelcase-required'),
-    (r'^\s*(if|while|def|class|except|try)\s[^[\n]*:\s*[^\\n]#\s]+',
-     "linebreak after :"),
-    (r'class\s[^( \n]+:', "old-style class, use class foo(object)",
-     r'#.*old-style'),
-    (r'class\s[^( \n]+\(\):',
-     "class foo() creates old style object, use class foo(object)",
-     r'#.*old-style'),
-    (r'\b(%s)\(' % '|'.join(k for k in keyword.kwlist
-                            if k not in ('print', 'exec')),
-     "Python keyword is not a function"),
-    (r',]', "unneeded trailing ',' in list"),
-#    (r'class\s[A-Z][^\(]*\((?!Exception)',
-#     "don't capitalize non-exception classes"),
-#    (r'in range\(', "use xrange"),
-#    (r'^\s*print\s+', "avoid using print in core and extensions"),
-    (r'[\x80-\xff]', "non-ASCII character literal"),
-    (r'("\')\.format\(', "str.format() has no bytes counterpart, use %"),
-    (r'^\s*(%s)\s\s' % '|'.join(keyword.kwlist),
-     "gratuitous whitespace after Python keyword"),
-    (r'([\(\[][ \t]\S)|(\S[ \t][\)\]])', "gratuitous whitespace in () or []"),
-#    (r'\s\s=', "gratuitous whitespace before ="),
-    (r'[^>< ](\+=|-=|!=|<>|<=|>=|<<=|>>=|%=)\S',
-     "missing whitespace around operator"),
-    (r'[^>< ](\+=|-=|!=|<>|<=|>=|<<=|>>=|%=)\s',
-     "missing whitespace around operator"),
-    (r'\s(\+=|-=|!=|<>|<=|>=|<<=|>>=|%=)\S',
-     "missing whitespace around operator"),
-    (r'[^^+=*/!<>&| %-](\s=|=\s)[^= ]',
-     "wrong whitespace around ="),
-    (r'\([^()]*( =[^=]|[^<>!=]= )',
-     "no whitespace around = for named parameters"),
-    (r'raise [^,(]+, (\([^\)]+\)|[^,\(\)]+)$',
-     "don't use old-style two-argument raise, use Exception(message)"),
-    (r' is\s+(not\s+)?["\'0-9-]', "object comparison with literal"),
-    (r' [=!]=\s+(True|False|None)',
-     "comparison with singleton, use 'is' or 'is not' instead"),
-    (r'^\s*(while|if) [01]:',
-     "use True/False for constant Boolean expression"),
-    (r'^\s*if False(:| +and)', 'Remove code instead of using `if False`'),
-    (r'(?:(?<!def)\s+|\()hasattr\(',
-     'hasattr(foo, bar) is broken on py2, use util.safehasattr(foo, bar) '
-     'instead', r'#.*hasattr-py3-only'),
-    (r'opener\([^)]*\).read\(',
-     "use opener.read() instead"),
-    (r'opener\([^)]*\).write\(',
-     "use opener.write() instead"),
-    (r'(?i)descend[e]nt', "the proper spelling is descendAnt"),
-    (r'\.debug\(\_', "don't mark debug messages for translation"),
-    (r'\.strip\(\)\.split\(\)', "no need to strip before splitting"),
-    (r'^\s*except\s*:', "naked except clause", r'#.*re-raises'),
-    (r'^\s*except\s([^\(,]+|\([^\)]+\))\s*,',
-     'legacy exception syntax; use "as" instead of ","'),
-    (r'release\(.*wlock, .*lock\)', "wrong lock release order"),
-    (r'\bdef\s+__bool__\b', "__bool__ should be __nonzero__ in Python 2"),
-    (r'os\.path\.join\(.*, *(""|\'\')\)',
-     "use pathutil.normasprefix(path) instead of os.path.join(path, '')"),
-    (r'\s0[0-7]+\b', 'legacy octal syntax; use "0o" prefix instead of "0"'),
-    # XXX only catch mutable arguments on the first line of the definition
-    (r'def.*[( ]\w+=\{\}', "don't use mutable default arguments"),
-    (r'\butil\.Abort\b', "directly use error.Abort"),
-    (r'^@(\w*\.)?cachefunc', "module-level @cachefunc is risky, please avoid"),
-    (r'^import Queue', "don't use Queue, use pycompat.queue.Queue + "
-                       "pycompat.queue.Empty"),
-    (r'^import cStringIO', "don't use cStringIO.StringIO, use util.stringio"),
-    (r'^import urllib', "don't use urllib, use util.urlreq/util.urlerr"),
-    (r'^import SocketServer', "don't use SockerServer, use util.socketserver"),
-    (r'^import urlparse', "don't use urlparse, use util.urlreq"),
-    (r'^import xmlrpclib', "don't use xmlrpclib, use util.xmlrpclib"),
-    (r'^import cPickle', "don't use cPickle, use util.pickle"),
-    (r'^import pickle', "don't use pickle, use util.pickle"),
-    (r'^import httplib', "don't use httplib, use util.httplib"),
-    (r'^import BaseHTTPServer', "use util.httpserver instead"),
-    (r'^(from|import) mercurial\.(cext|pure|cffi)',
-     "use mercurial.policy.importmod instead"),
-    (r'\.next\(\)', "don't use .next(), use next(...)"),
-    (r'([a-z]*).revision\(\1\.node\(',
-     "don't convert rev to node before passing to revision(nodeorrev)"),
-    (r'platform\.system\(\)', "don't use platform.system(), use pycompat"),
-
-  ],
-  # warnings
-  [
-  ]
+    [
+        (r'\\$', 'Use () to wrap long lines in Python, not \\'),
+        (
+            r'^\s*def\s*\w+\s*\(.*,\s*\(',
+            "tuple parameter unpacking not available in Python 3+",
+        ),
+        (
+            r'lambda\s*\(.*,.*\)',
+            "tuple parameter unpacking not available in Python 3+",
+        ),
+        (r'(?<!def)\s+(cmp)\(', "cmp is not available in Python 3+"),
+        (r'(?<!\.)\breduce\s*\(.*', "reduce is not available in Python 3+"),
+        (
+            r'\bdict\(.*=',
+            'dict() is different in Py2 and 3 and is slower than {}',
+            'dict-from-generator',
+        ),
+        (r'\.has_key\b', "dict.has_key is not available in Python 3+"),
+        (r'\s<>\s', '<> operator is not available in Python 3+, use !='),
+        (r'^\s*\t', "don't use tabs"),
+        (r'\S;\s*\n', "semicolon"),
+        (r'[^_]_\([ \t\n]*(?:"[^"]+"[ \t\n+]*)+%', "don't use % inside _()"),
+        (r"[^_]_\([ \t\n]*(?:'[^']+'[ \t\n+]*)+%", "don't use % inside _()"),
+        (r'(\w|\)),\w', "missing whitespace after ,"),
+        (r'(\w|\))[+/*\-<>]\w', "missing whitespace in expression"),
+        (r'\w\s=\s\s+\w', "gratuitous whitespace after ="),
+        (
+            (
+                # a line ending with a colon, potentially with trailing comments
+                r':([ \t]*#[^\n]*)?\n'
+                # one that is not a pass and not only a comment
+                r'(?P<indent>[ \t]+)[^#][^\n]+\n'
+                # more lines at the same indent level
+                r'((?P=indent)[^\n]+\n)*'
+                # a pass at the same indent level, which is bogus
+                r'(?P=indent)pass[ \t\n#]'
+            ),
+            'omit superfluous pass',
+        ),
+        (r'[^\n]\Z', "no trailing newline"),
+        (r'(\S[ \t]+|^[ \t]+)\n', "trailing whitespace"),
+        (
+            r'^\s+(self\.)?[A-Za-z][a-z0-9]+[A-Z]\w* = ',
+            "don't use camelcase in identifiers",
+            r'#.*camelcase-required',
+        ),
+        (
+            r'^\s*(if|while|def|class|except|try)\s[^[\n]*:\s*[^\\n]#\s]+',
+            "linebreak after :",
+        ),
+        (
+            r'class\s[^( \n]+:',
+            "old-style class, use class foo(object)",
+            r'#.*old-style',
+        ),
+        (
+            r'class\s[^( \n]+\(\):',
+            "class foo() creates old style object, use class foo(object)",
+            r'#.*old-style',
+        ),
+        (
+            r'\b(%s)\('
+            % '|'.join(k for k in keyword.kwlist if k not in ('print', 'exec')),
+            "Python keyword is not a function",
+        ),
+        #    (r'class\s[A-Z][^\(]*\((?!Exception)',
+        #     "don't capitalize non-exception classes"),
+        #    (r'in range\(', "use xrange"),
+        #    (r'^\s*print\s+', "avoid using print in core and extensions"),
+        (r'[\x80-\xff]', "non-ASCII character literal"),
+        (r'("\')\.format\(', "str.format() has no bytes counterpart, use %"),
+        (
+            r'([\(\[][ \t]\S)|(\S[ \t][\)\]])',
+            "gratuitous whitespace in () or []",
+        ),
+        #    (r'\s\s=', "gratuitous whitespace before ="),
+        (
+            r'[^>< ](\+=|-=|!=|<>|<=|>=|<<=|>>=|%=)\S',
+            "missing whitespace around operator",
+        ),
+        (
+            r'[^>< ](\+=|-=|!=|<>|<=|>=|<<=|>>=|%=)\s',
+            "missing whitespace around operator",
+        ),
+        (
+            r'\s(\+=|-=|!=|<>|<=|>=|<<=|>>=|%=)\S',
+            "missing whitespace around operator",
+        ),
+        (r'[^^+=*/!<>&| %-](\s=|=\s)[^= ]', "wrong whitespace around ="),
+        (
+            r'\([^()]*( =[^=]|[^<>!=]= )',
+            "no whitespace around = for named parameters",
+        ),
+        (
+            r'raise [^,(]+, (\([^\)]+\)|[^,\(\)]+)$',
+            "don't use old-style two-argument raise, use Exception(message)",
+        ),
+        (r' is\s+(not\s+)?["\'0-9-]', "object comparison with literal"),
+        (
+            r' [=!]=\s+(True|False|None)',
+            "comparison with singleton, use 'is' or 'is not' instead",
+        ),
+        (
+            r'^\s*(while|if) [01]:',
+            "use True/False for constant Boolean expression",
+        ),
+        (r'^\s*if False(:| +and)', 'Remove code instead of using `if False`'),
+        (
+            r'(?:(?<!def)\s+|\()hasattr\(',
+            'hasattr(foo, bar) is broken on py2, use util.safehasattr(foo, bar) '
+            'instead',
+            r'#.*hasattr-py3-only',
+        ),
+        (r'opener\([^)]*\).read\(', "use opener.read() instead"),
+        (r'opener\([^)]*\).write\(', "use opener.write() instead"),
+        (r'(?i)descend[e]nt', "the proper spelling is descendAnt"),
+        (r'\.debug\(\_', "don't mark debug messages for translation"),
+        (r'\.strip\(\)\.split\(\)', "no need to strip before splitting"),
+        (r'^\s*except\s*:', "naked except clause", r'#.*re-raises'),
+        (
+            r'^\s*except\s([^\(,]+|\([^\)]+\))\s*,',
+            'legacy exception syntax; use "as" instead of ","',
+        ),
+        (r'release\(.*wlock, .*lock\)', "wrong lock release order"),
+        (r'\bdef\s+__bool__\b', "__bool__ should be __nonzero__ in Python 2"),
+        (
+            r'os\.path\.join\(.*, *(""|\'\')\)',
+            "use pathutil.normasprefix(path) instead of os.path.join(path, '')",
+        ),
+        (r'\s0[0-7]+\b', 'legacy octal syntax; use "0o" prefix instead of "0"'),
+        # XXX only catch mutable arguments on the first line of the definition
+        (r'def.*[( ]\w+=\{\}', "don't use mutable default arguments"),
+        (r'\butil\.Abort\b', "directly use error.Abort"),
+        (
+            r'^@(\w*\.)?cachefunc',
+            "module-level @cachefunc is risky, please avoid",
+        ),
+        (
+            r'^import Queue',
+            "don't use Queue, use pycompat.queue.Queue + "
+            "pycompat.queue.Empty",
+        ),
+        (
+            r'^import cStringIO',
+            "don't use cStringIO.StringIO, use util.stringio",
+        ),
+        (r'^import urllib', "don't use urllib, use util.urlreq/util.urlerr"),
+        (
+            r'^import SocketServer',
+            "don't use SockerServer, use util.socketserver",
+        ),
+        (r'^import urlparse', "don't use urlparse, use util.urlreq"),
+        (r'^import xmlrpclib', "don't use xmlrpclib, use util.xmlrpclib"),
+        (r'^import cPickle', "don't use cPickle, use util.pickle"),
+        (r'^import pickle', "don't use pickle, use util.pickle"),
+        (r'^import httplib', "don't use httplib, use util.httplib"),
+        (r'^import BaseHTTPServer', "use util.httpserver instead"),
+        (
+            r'^(from|import) mercurial\.(cext|pure|cffi)',
+            "use mercurial.policy.importmod instead",
+        ),
+        (r'\.next\(\)', "don't use .next(), use next(...)"),
+        (
+            r'([a-z]*).revision\(\1\.node\(',
+            "don't convert rev to node before passing to revision(nodeorrev)",
+        ),
+        (r'platform\.system\(\)', "don't use platform.system(), use pycompat"),
+    ],
+    # warnings
+    [],
 ]
 
 # patterns to check normal *.py files
 pypats = [
-  [
-    # Ideally, these should be placed in "commonpypats" for
-    # consistency of coding rules in Mercurial source tree.
-    # But on the other hand, these are not so seriously required for
-    # python code fragments embedded in test scripts. Fixing test
-    # scripts for these patterns requires many changes, and has less
-    # profit than effort.
-    (r'.{81}', "line too long"),
-    (r'raise Exception', "don't raise generic exceptions"),
-    (r'[\s\(](open|file)\([^)]*\)\.read\(',
-     "use util.readfile() instead"),
-    (r'[\s\(](open|file)\([^)]*\)\.write\(',
-     "use util.writefile() instead"),
-    (r'^[\s\(]*(open(er)?|file)\([^)]*\)(?!\.close\(\))',
-     "always assign an opened file to a variable, and close it afterwards"),
-    (r'[\s\(](open|file)\([^)]*\)\.(?!close\(\))',
-     "always assign an opened file to a variable, and close it afterwards"),
-    (r':\n(    )*( ){1,3}[^ ]', "must indent 4 spaces"),
-    (r'^import atexit', "don't use atexit, use ui.atexit"),
-
-    # rules depending on implementation of repquote()
-    (r' x+[xpqo%APM][\'"]\n\s+[\'"]x',
-     'string join across lines with no space'),
-    (r'''(?x)ui\.(status|progress|write|note|warn)\(
+    [
+        # Ideally, these should be placed in "commonpypats" for
+        # consistency of coding rules in Mercurial source tree.
+        # But on the other hand, these are not so seriously required for
+        # python code fragments embedded in test scripts. Fixing test
+        # scripts for these patterns requires many changes, and has less
+        # profit than effort.
+        (r'raise Exception', "don't raise generic exceptions"),
+        (r'[\s\(](open|file)\([^)]*\)\.read\(', "use util.readfile() instead"),
+        (
+            r'[\s\(](open|file)\([^)]*\)\.write\(',
+            "use util.writefile() instead",
+        ),
+        (
+            r'^[\s\(]*(open(er)?|file)\([^)]*\)(?!\.close\(\))',
+            "always assign an opened file to a variable, and close it afterwards",
+        ),
+        (
+            r'[\s\(](open|file)\([^)]*\)\.(?!close\(\))',
+            "always assign an opened file to a variable, and close it afterwards",
+        ),
+        (r':\n(    )*( ){1,3}[^ ]', "must indent 4 spaces"),
+        (r'^import atexit', "don't use atexit, use ui.atexit"),
+        # rules depending on implementation of repquote()
+        (
+            r' x+[xpqo%APM][\'"]\n\s+[\'"]x',
+            'string join across lines with no space',
+        ),
+        (
+            r'''(?x)ui\.(status|progress|write|note|warn)\(
          [ \t\n#]*
          (?# any strings/comments might precede a string, which
            # contains translatable message)
-         ((['"]|\'\'\'|""")[ \npq%bAPMxno]*(['"]|\'\'\'|""")[ \t\n#]+)*
+         b?((['"]|\'\'\'|""")[ \npq%bAPMxno]*(['"]|\'\'\'|""")[ \t\n#]+)*
          (?# sequence consisting of below might precede translatable message
            # - formatting string: "% 10s", "%05d", "% -3.2f", "%*s", "%%" ...
            # - escaped character: "\\", "\n", "\0" ...
@@ -395,51 +516,55 b' pypats = ['
          (?# this regexp can't use [^...] style,
            # because _preparepats forcibly adds "\n" into [^...],
            # even though this regexp wants match it against "\n")''',
-     "missing _() in ui message (use () to hide false-positives)"),
-  ] + commonpypats[0],
-  # warnings
-  [
-    # rules depending on implementation of repquote()
-    (r'(^| )pp +xxxxqq[ \n][^\n]', "add two newlines after '.. note::'"),
-  ] + commonpypats[1]
+            "missing _() in ui message (use () to hide false-positives)",
+        ),
+    ]
+    + commonpypats[0],
+    # warnings
+    [
+        # rules depending on implementation of repquote()
+        (r'(^| )pp +xxxxqq[ \n][^\n]', "add two newlines after '.. note::'"),
+    ]
+    + commonpypats[1],
 ]
 
 # patterns to check *.py for embedded ones in test script
 embeddedpypats = [
-  [
-  ] + commonpypats[0],
-  # warnings
-  [
-  ] + commonpypats[1]
+    [] + commonpypats[0],
+    # warnings
+    [] + commonpypats[1],
 ]
 
 # common filters to convert *.py
 commonpyfilters = [
-    (r"""(?msx)(?P<comment>\#.*?$)|
+    (
+        r"""(?msx)(?P<comment>\#.*?$)|
          ((?P<quote>('''|\"\"\"|(?<!')'(?!')|(?<!")"(?!")))
           (?P<text>(([^\\]|\\.)*?))
-          (?P=quote))""", reppython),
+          (?P=quote))""",
+        reppython,
+    ),
 ]
 
 # filters to convert normal *.py files
-pyfilters = [
-] + commonpyfilters
+pyfilters = [] + commonpyfilters
 
 # non-filter patterns
 pynfpats = [
     [
-    (r'pycompat\.osname\s*[=!]=\s*[\'"]nt[\'"]', "use pycompat.iswindows"),
-    (r'pycompat\.osname\s*[=!]=\s*[\'"]posix[\'"]', "use pycompat.isposix"),
-    (r'pycompat\.sysplatform\s*[!=]=\s*[\'"]darwin[\'"]',
-     "use pycompat.isdarwin"),
+        (r'pycompat\.osname\s*[=!]=\s*[\'"]nt[\'"]', "use pycompat.iswindows"),
+        (r'pycompat\.osname\s*[=!]=\s*[\'"]posix[\'"]', "use pycompat.isposix"),
+        (
+            r'pycompat\.sysplatform\s*[!=]=\s*[\'"]darwin[\'"]',
+            "use pycompat.isdarwin",
+        ),
     ],
     # warnings
     [],
 ]
 
 # filters to convert *.py for embedded ones in test script
-embeddedpyfilters = [
-] + commonpyfilters
+embeddedpyfilters = [] + commonpyfilters
 
 # extension non-filter patterns
 pyextnfpats = [
@@ -451,42 +576,40 b' pyextnfpats = ['
 txtfilters = []
 
 txtpats = [
-  [
-    (r'\s$', 'trailing whitespace'),
-    ('.. note::[ \n][^\n]', 'add two newlines after note::')
-  ],
-  []
+    [
+        (r'\s$', 'trailing whitespace'),
+        ('.. note::[ \n][^\n]', 'add two newlines after note::'),
+    ],
+    [],
 ]
 
 cpats = [
-  [
-    (r'//', "don't use //-style comments"),
-    (r'\S\t', "don't use tabs except for indent"),
-    (r'(\S[ \t]+|^[ \t]+)\n', "trailing whitespace"),
-    (r'.{81}', "line too long"),
-    (r'(while|if|do|for)\(', "use space after while/if/do/for"),
-    (r'return\(', "return is not a function"),
-    (r' ;', "no space before ;"),
-    (r'[^;] \)', "no space before )"),
-    (r'[)][{]', "space between ) and {"),
-    (r'\w+\* \w+', "use int *foo, not int* foo"),
-    (r'\W\([^\)]+\) \w+', "use (int)foo, not (int) foo"),
-    (r'\w+ (\+\+|--)', "use foo++, not foo ++"),
-    (r'\w,\w', "missing whitespace after ,"),
-    (r'^[^#]\w[+/*]\w', "missing whitespace in expression"),
-    (r'\w\s=\s\s+\w', "gratuitous whitespace after ="),
-    (r'^#\s+\w', "use #foo, not # foo"),
-    (r'[^\n]\Z', "no trailing newline"),
-    (r'^\s*#import\b', "use only #include in standard C code"),
-    (r'strcpy\(', "don't use strcpy, use strlcpy or memcpy"),
-    (r'strcat\(', "don't use strcat"),
-
-    # rules depending on implementation of repquote()
-  ],
-  # warnings
-  [
-    # rules depending on implementation of repquote()
-  ]
+    [
+        (r'//', "don't use //-style comments"),
+        (r'\S\t', "don't use tabs except for indent"),
+        (r'(\S[ \t]+|^[ \t]+)\n', "trailing whitespace"),
+        (r'(while|if|do|for)\(', "use space after while/if/do/for"),
+        (r'return\(', "return is not a function"),
+        (r' ;', "no space before ;"),
+        (r'[^;] \)', "no space before )"),
+        (r'[)][{]', "space between ) and {"),
+        (r'\w+\* \w+', "use int *foo, not int* foo"),
+        (r'\W\([^\)]+\) \w+', "use (int)foo, not (int) foo"),
+        (r'\w+ (\+\+|--)', "use foo++, not foo ++"),
+        (r'\w,\w', "missing whitespace after ,"),
+        (r'^[^#]\w[+/*]\w', "missing whitespace in expression"),
+        (r'\w\s=\s\s+\w', "gratuitous whitespace after ="),
+        (r'^#\s+\w', "use #foo, not # foo"),
+        (r'[^\n]\Z', "no trailing newline"),
+        (r'^\s*#import\b', "use only #include in standard C code"),
+        (r'strcpy\(', "don't use strcpy, use strlcpy or memcpy"),
+        (r'strcat\(', "don't use strcat"),
+        # rules depending on implementation of repquote()
+    ],
+    # warnings
+    [
+        # rules depending on implementation of repquote()
+    ],
 ]
 
 cfilters = [
@@ -497,82 +620,109 b' cfilters = ['
 ]
 
 inutilpats = [
-  [
-    (r'\bui\.', "don't use ui in util"),
-  ],
-  # warnings
-  []
+    [(r'\bui\.', "don't use ui in util"),],
+    # warnings
+    [],
 ]
 
 inrevlogpats = [
-  [
-    (r'\brepo\.', "don't use repo in revlog"),
-  ],
-  # warnings
-  []
+    [(r'\brepo\.', "don't use repo in revlog"),],
+    # warnings
+    [],
 ]
 
 webtemplatefilters = []
 
 webtemplatepats = [
-  [],
-  [
-    (r'{desc(\|(?!websub|firstline)[^\|]*)+}',
-     'follow desc keyword with either firstline or websub'),
-  ]
+    [],
+    [
+        (
+            r'{desc(\|(?!websub|firstline)[^\|]*)+}',
+            'follow desc keyword with either firstline or websub',
+        ),
+    ],
 ]
 
 allfilesfilters = []
 
 allfilespats = [
-  [
-    (r'(http|https)://[a-zA-Z0-9./]*selenic.com/',
-     'use mercurial-scm.org domain URL'),
-    (r'mercurial@selenic\.com',
-     'use mercurial-scm.org domain for mercurial ML address'),
-    (r'mercurial-devel@selenic\.com',
-     'use mercurial-scm.org domain for mercurial-devel ML address'),
-  ],
-  # warnings
-  [],
+    [
+        (
+            r'(http|https)://[a-zA-Z0-9./]*selenic.com/',
+            'use mercurial-scm.org domain URL',
+        ),
+        (
+            r'mercurial@selenic\.com',
+            'use mercurial-scm.org domain for mercurial ML address',
+        ),
+        (
+            r'mercurial-devel@selenic\.com',
+            'use mercurial-scm.org domain for mercurial-devel ML address',
+        ),
+    ],
+    # warnings
+    [],
 ]
 
 py3pats = [
-  [
-    (r'os\.environ', "use encoding.environ instead (py3)", r'#.*re-exports'),
-    (r'os\.name', "use pycompat.osname instead (py3)"),
-    (r'os\.getcwd', "use encoding.getcwd instead (py3)", r'#.*re-exports'),
-    (r'os\.sep', "use pycompat.ossep instead (py3)"),
-    (r'os\.pathsep', "use pycompat.ospathsep instead (py3)"),
-    (r'os\.altsep', "use pycompat.osaltsep instead (py3)"),
-    (r'sys\.platform', "use pycompat.sysplatform instead (py3)"),
-    (r'getopt\.getopt', "use pycompat.getoptb instead (py3)"),
-    (r'os\.getenv', "use encoding.environ.get instead"),
-    (r'os\.setenv', "modifying the environ dict is not preferred"),
-    (r'(?<!pycompat\.)xrange', "use pycompat.xrange instead (py3)"),
-  ],
-  # warnings
-  [],
+    [
+        (
+            r'os\.environ',
+            "use encoding.environ instead (py3)",
+            r'#.*re-exports',
+        ),
+        (r'os\.name', "use pycompat.osname instead (py3)"),
+        (r'os\.getcwd', "use encoding.getcwd instead (py3)", r'#.*re-exports'),
+        (r'os\.sep', "use pycompat.ossep instead (py3)"),
+        (r'os\.pathsep', "use pycompat.ospathsep instead (py3)"),
+        (r'os\.altsep', "use pycompat.osaltsep instead (py3)"),
+        (r'sys\.platform', "use pycompat.sysplatform instead (py3)"),
+        (r'getopt\.getopt', "use pycompat.getoptb instead (py3)"),
+        (r'os\.getenv', "use encoding.environ.get instead"),
+        (r'os\.setenv', "modifying the environ dict is not preferred"),
+        (r'(?<!pycompat\.)xrange', "use pycompat.xrange instead (py3)"),
+    ],
+    # warnings
+    [],
 ]
 
 checks = [
     ('python', r'.*\.(py|cgi)$', r'^#!.*python', pyfilters, pypats),
     ('python', r'.*\.(py|cgi)$', r'^#!.*python', [], pynfpats),
     ('python', r'.*hgext.*\.py$', '', [], pyextnfpats),
-    ('python 3', r'.*(hgext|mercurial)/(?!demandimport|policy|pycompat).*\.py',
-     '', pyfilters, py3pats),
+    (
+        'python 3',
+        r'.*(hgext|mercurial)/(?!demandimport|policy|pycompat).*\.py',
+        '',
+        pyfilters,
+        py3pats,
+    ),
     ('test script', r'(.*/)?test-[^.~]*$', '', testfilters, testpats),
     ('c', r'.*\.[ch]$', '', cfilters, cpats),
     ('unified test', r'.*\.t$', '', utestfilters, utestpats),
-    ('layering violation repo in revlog', r'mercurial/revlog\.py', '',
-     pyfilters, inrevlogpats),
-    ('layering violation ui in util', r'mercurial/util\.py', '', pyfilters,
-     inutilpats),
+    (
+        'layering violation repo in revlog',
+        r'mercurial/revlog\.py',
+        '',
+        pyfilters,
+        inrevlogpats,
+    ),
+    (
+        'layering violation ui in util',
+        r'mercurial/util\.py',
+        '',
+        pyfilters,
+        inutilpats,
+    ),
     ('txt', r'.*\.txt$', '', txtfilters, txtpats),
-    ('web template', r'mercurial/templates/.*\.tmpl', '',
-     webtemplatefilters, webtemplatepats),
-    ('all except for .po', r'.*(?<!\.po)$', '',
-     allfilesfilters, allfilespats),
+    (
+        'web template',
+        r'mercurial/templates/.*\.tmpl',
+        '',
+        webtemplatefilters,
+        webtemplatepats,
+    ),
+    ('all except for .po', r'.*(?<!\.po)$', '', allfilesfilters, allfilespats),
 ]
 
 # (desc,
@@ -580,10 +730,15 b' checks = ['
 #  list of patterns to convert target files
 #  list of patterns to detect errors/warnings)
 embeddedchecks = [
-    ('embedded python',
-     testparseutil.pyembedded, embeddedpyfilters, embeddedpypats)
+    (
+        'embedded python',
+        testparseutil.pyembedded,
+        embeddedpyfilters,
+        embeddedpypats,
+    )
 ]
 
+
 def _preparepats():
     def preparefailandwarn(failandwarn):
         for pats in failandwarn:
@@ -612,6 +767,7 b' def _preparepats():'
             filters = c[-2]
             preparefilters(filters)
 
+
 class norepeatlogger(object):
     def __init__(self):
         self._lastseen = None
@@ -637,8 +793,10 b' class norepeatlogger(object):'
             self._lastseen = msgid
         print(" " + msg)
 
+
 _defaultlogger = norepeatlogger()
 
+
 def getblame(f):
     lines = []
     for l in os.popen('hg annotate -un %s' % f):
@@ -647,8 +805,16 b' def getblame(f):'
         lines.append((line[1:-1], user, rev))
     return lines
 
-def checkfile(f, logfunc=_defaultlogger.log, maxerr=None, warnings=False,
-              blame=False, debug=False, lineno=True):
+
+def checkfile(
+    f,
+    logfunc=_defaultlogger.log,
+    maxerr=None,
+    warnings=False,
+    blame=False,
+    debug=False,
+    lineno=True,
+):
     """checks style and portability of a given file
 
     :f: filepath
@@ -680,8 +846,9 b' def checkfile(f, logfunc=_defaultlogger.'
             print(name, f)
         if not (re.match(match, f) or (magic and re.search(magic, pre))):
             if debug:
-                print("Skipping %s for %s it doesn't match %s" % (
-                       name, match, f))
+                print(
+                    "Skipping %s for %s it doesn't match %s" % (name, match, f)
+                )
             continue
         if "no-" "check-code" in pre:
             # If you're looking at this line, it's because a file has:
@@ -691,16 +858,28 b' def checkfile(f, logfunc=_defaultlogger.'
             # spelling, we write it with the expected spelling from
             # tests/test-check-code.t
             print("Skipping %s it has no-che?k-code (glob)" % f)
-            return "Skip" # skip checking this file
+            return "Skip"  # skip checking this file
 
-        fc = _checkfiledata(name, f, pre, filters, pats, context,
-                            logfunc, maxerr, warnings, blame, debug, lineno)
+        fc = _checkfiledata(
+            name,
+            f,
+            pre,
+            filters,
+            pats,
+            context,
+            logfunc,
+            maxerr,
+            warnings,
+            blame,
+            debug,
+            lineno,
+        )
         if fc:
             result = False
 
     if f.endswith('.t') and "no-" "check-code" not in pre:
         if debug:
-            print("Checking embedded code in %s" % (f))
+            print("Checking embedded code in %s" % f)
 
         prelines = pre.splitlines()
         embeddederros = []
@@ -712,9 +891,21 b' def checkfile(f, logfunc=_defaultlogger.'
 
             for found in embedded(f, prelines, embeddederros):
                 filename, starts, ends, code = found
-                fc = _checkfiledata(name, f, code, filters, pats, context,
-                                    logfunc, curmaxerr, warnings, blame, debug,
-                                    lineno, offset=starts - 1)
+                fc = _checkfiledata(
+                    name,
+                    f,
+                    code,
+                    filters,
+                    pats,
+                    context,
+                    logfunc,
+                    curmaxerr,
+                    warnings,
+                    blame,
+                    debug,
+                    lineno,
+                    offset=starts - 1,
+                )
                 if fc:
                     result = False
                     if curmaxerr:
@@ -724,9 +915,22 b' def checkfile(f, logfunc=_defaultlogger.'
 
     return result
 
-def _checkfiledata(name, f, filedata, filters, pats, context,
-                   logfunc, maxerr, warnings, blame, debug, lineno,
-                   offset=None):
+
+def _checkfiledata(
+    name,
+    f,
+    filedata,
+    filters,
+    pats,
+    context,
+    logfunc,
+    maxerr,
+    warnings,
+    blame,
+    debug,
+    lineno,
+    offset=None,
+):
     """Execute actual error check for file data
 
     :name: of the checking category
@@ -759,10 +963,10 b' def _checkfiledata(name, f, filedata, fi'
     fc = 0
     pre = post = filedata
 
-    if True: # TODO: get rid of this redundant 'if' block
+    if True:  # TODO: get rid of this redundant 'if' block
         for p, r in filters:
             post = re.sub(p, r, post)
-        nerrs = len(pats[0]) # nerr elements are errors
+        nerrs = len(pats[0])  # nerr elements are errors
         if warnings:
             pats = pats[0] + pats[1]
         else:
@@ -801,8 +1005,10 b' def _checkfiledata(name, f, filedata, fi'
 
                 if ignore and re.search(ignore, l, re.MULTILINE):
                     if debug:
-                        print("Skipping %s for %s:%s (ignore pattern)" % (
-                            name, f, (n + lineoffset)))
+                        print(
+                            "Skipping %s for %s:%s (ignore pattern)"
+                            % (name, f, (n + lineoffset))
+                        )
                     continue
                 bd = ""
                 if blame:
@@ -837,21 +1043,38 b' def _checkfiledata(name, f, filedata, fi'
 
     return fc
 
+
 def main():
     parser = optparse.OptionParser("%prog [options] [files | -]")
-    parser.add_option("-w", "--warnings", action="store_true",
-                      help="include warning-level checks")
-    parser.add_option("-p", "--per-file", type="int",
-                      help="max warnings per file")
-    parser.add_option("-b", "--blame", action="store_true",
-                      help="use annotate to generate blame info")
-    parser.add_option("", "--debug", action="store_true",
-                      help="show debug information")
-    parser.add_option("", "--nolineno", action="store_false",
-                      dest='lineno', help="don't show line numbers")
+    parser.add_option(
+        "-w",
+        "--warnings",
+        action="store_true",
+        help="include warning-level checks",
+    )
+    parser.add_option(
+        "-p", "--per-file", type="int", help="max warnings per file"
+    )
+    parser.add_option(
+        "-b",
+        "--blame",
+        action="store_true",
+        help="use annotate to generate blame info",
+    )
+    parser.add_option(
+        "", "--debug", action="store_true", help="show debug information"
+    )
+    parser.add_option(
+        "",
+        "--nolineno",
+        action="store_false",
+        dest='lineno',
+        help="don't show line numbers",
+    )
 
-    parser.set_defaults(per_file=15, warnings=False, blame=False, debug=False,
-                        lineno=True)
+    parser.set_defaults(
+        per_file=15, warnings=False, blame=False, debug=False, lineno=True
+    )
     (options, args) = parser.parse_args()
 
     if len(args) == 0:
@@ -866,11 +1089,17 b' def main():'
 
     ret = 0
     for f in check:
-        if not checkfile(f, maxerr=options.per_file, warnings=options.warnings,
-                         blame=options.blame, debug=options.debug,
-                         lineno=options.lineno):
+        if not checkfile(
+            f,
+            maxerr=options.per_file,
+            warnings=options.warnings,
+            blame=options.blame,
+            debug=options.debug,
+            lineno=options.lineno,
+        ):
             ret = 1
     return ret
 
+
 if __name__ == "__main__":
     sys.exit(main())

contrib/check-commit

@@ -39,12 +39,6 b' errors = ['
      "summary keyword should be most user-relevant one-word command or topic"),
     (afterheader + r".*\.\s*\n", "don't add trailing period on summary line"),
     (afterheader + r".{79,}", "summary line too long (limit is 78)"),
-    # Forbid "_" in function name.
-    #
-    # We skip the check for cffi related functions. They use names mapping the
-    # name of the C function. C function names may contain "_".
-    (r"\n\+[ \t]+def (?!cffi)[a-z]+_[a-z]",
-     "adds a function with foo_bar naming"),
 ]
 
 word = re.compile(r'\S')

contrib/check-config.py

@@ -15,7 +15,8 b' foundopts = {}'
 documented = {}
 allowinconsistent = set()
 
-configre = re.compile(br'''
+configre = re.compile(
+    br'''
     # Function call
     ui\.config(?P<ctype>|int|bool|list)\(
         # First argument.
@@ -23,9 +24,12 b" configre = re.compile(br'''"
         # Second argument
         ['"](?P<option>\S+)['"](,\s+
         (?:default=)?(?P<default>\S+?))?
-    \)''', re.VERBOSE | re.MULTILINE)
+    \)''',
+    re.VERBOSE | re.MULTILINE,
+)
 
-configwithre = re.compile(br'''
+configwithre = re.compile(
+    br'''
     ui\.config(?P<ctype>with)\(
         # First argument is callback function. This doesn't parse robustly
         # if it is e.g. a function call.
@@ -33,23 +37,32 b" configwithre = re.compile(br'''"
         ['"](?P<section>\S+)['"],\s*
         ['"](?P<option>\S+)['"](,\s+
         (?:default=)?(?P<default>\S+?))?
-    \)''', re.VERBOSE | re.MULTILINE)
+    \)''',
+    re.VERBOSE | re.MULTILINE,
+)
 
-configpartialre = (br"""ui\.config""")
+configpartialre = br"""ui\.config"""
 
-ignorere = re.compile(br'''
+ignorere = re.compile(
+    br'''
     \#\s(?P<reason>internal|experimental|deprecated|developer|inconsistent)\s
     config:\s(?P<config>\S+\.\S+)$
-    ''', re.VERBOSE | re.MULTILINE)
+    ''',
+    re.VERBOSE | re.MULTILINE,
+)
 
 if sys.version_info[0] > 2:
+
     def mkstr(b):
         if isinstance(b, str):
             return b
         return b.decode('utf8')
+
+
 else:
     mkstr = lambda x: x
 
+
 def main(args):
     for f in args:
         sect = b''
@@ -115,18 +128,32 b' def main(args):'
                 name = m.group('section') + b"." + m.group('option')
                 default = m.group('default')
                 if default in (
-                        None, b'False', b'None', b'0', b'[]', b'""', b"''"):
+                    None,
+                    b'False',
+                    b'None',
+                    b'0',
+                    b'[]',
+                    b'""',
+                    b"''",
+                ):
                     default = b''
                 if re.match(b'[a-z.]+$', default):
                     default = b'<variable>'
-                if (name in foundopts and (ctype, default) != foundopts[name]
-                    and name not in allowinconsistent):
+                if (
+                    name in foundopts
+                    and (ctype, default) != foundopts[name]
+                    and name not in allowinconsistent
+                ):
                     print(mkstr(l.rstrip()))
                     fctype, fdefault = foundopts[name]
-                    print("conflict on %s: %r != %r" % (
-                        mkstr(name),
-                        (mkstr(ctype), mkstr(default)),
-                        (mkstr(fctype), mkstr(fdefault))))
+                    print(
+                        "conflict on %s: %r != %r"
+                        % (
+                            mkstr(name),
+                            (mkstr(ctype), mkstr(default)),
+                            (mkstr(fctype), mkstr(fdefault)),
+                        )
+                    )
                     print("at %s:%d:" % (mkstr(f), linenum))
                 foundopts[name] = (ctype, default)
                 carryover = b''
@@ -139,9 +166,11 b' def main(args):'
 
     for name in sorted(foundopts):
         if name not in documented:
-            if not (name.startswith(b"devel.") or
-                    name.startswith(b"experimental.") or
-                    name.startswith(b"debug.")):
+            if not (
+                name.startswith(b"devel.")
+                or name.startswith(b"experimental.")
+                or name.startswith(b"debug.")
+            ):
                 ctype, default = foundopts[name]
                 if default:
                     if isinstance(default, bytes):
@@ -149,8 +178,11 b' def main(args):'
                     default = ' [%s]' % default
                 elif isinstance(default, bytes):
                     default = mkstr(default)
-                print("undocumented: %s (%s)%s" % (
-                    mkstr(name), mkstr(ctype), default))
+                print(
+                    "undocumented: %s (%s)%s"
+                    % (mkstr(name), mkstr(ctype), default)
+                )
+
 
 if __name__ == "__main__":
     if len(sys.argv) > 1:

contrib/check-py3-compat.py

@@ -16,6 +16,7 b' import sys'
 import traceback
 import warnings
 
+
 def check_compat_py2(f):
     """Check Python 3 compatibility for a file with Python 2"""
     with open(f, 'rb') as fh:
@@ -40,6 +41,7 b' def check_compat_py2(f):'
     if haveprint and 'print_function' not in futures:
         print('%s requires print_function' % f)
 
+
 def check_compat_py3(f):
     """Check Python 3 compatibility of a file with Python 3."""
     with open(f, 'rb') as fh:
@@ -54,8 +56,9 b' def check_compat_py3(f):'
     # Try to import the module.
     # For now we only support modules in packages because figuring out module
     # paths for things not in a package can be confusing.
-    if (f.startswith(('hgdemandimport/', 'hgext/', 'mercurial/'))
-        and not f.endswith('__init__.py')):
+    if f.startswith(
+        ('hgdemandimport/', 'hgext/', 'mercurial/')
+    ) and not f.endswith('__init__.py'):
         assert f.endswith('.py')
         name = f.replace('/', '.')[:-3]
         try:
@@ -79,11 +82,16 b' def check_compat_py3(f):'
 
             if frame.filename:
                 filename = os.path.basename(frame.filename)
-                print('%s: error importing: <%s> %s (error at %s:%d)' % (
-                      f, type(e).__name__, e, filename, frame.lineno))
+                print(
+                    '%s: error importing: <%s> %s (error at %s:%d)'
+                    % (f, type(e).__name__, e, filename, frame.lineno)
+                )
             else:
-                print('%s: error importing module: <%s> %s (line %d)' % (
-                      f, type(e).__name__, e, frame.lineno))
+                print(
+                    '%s: error importing module: <%s> %s (line %d)'
+                    % (f, type(e).__name__, e, frame.lineno)
+                )
+
 
 if __name__ == '__main__':
     if sys.version_info[0] == 2:
@@ -96,7 +104,10 b" if __name__ == '__main__':"
             fn(f)
 
         for w in warns:
-            print(warnings.formatwarning(w.message, w.category,
-                                         w.filename, w.lineno).rstrip())
+            print(
+                warnings.formatwarning(
+                    w.message, w.category, w.filename, w.lineno
+                ).rstrip()
+            )
 
     sys.exit(0)

contrib/clang-format-ignorelist

@@ -1,6 +1,5 b''
 # Files that just need to be migrated to the formatter.
 # Do not add new files here!
-mercurial/cext/dirs.c
 mercurial/cext/manifest.c
 mercurial/cext/osutil.c
 # Vendored code that we should never format:
@@ -49,6 +48,10 b' contrib/python-zstandard/zstd/compress/h'
 contrib/python-zstandard/zstd/compress/huf_compress.c
 contrib/python-zstandard/zstd/compress/zstd_compress.c
 contrib/python-zstandard/zstd/compress/zstd_compress_internal.h
+contrib/python-zstandard/zstd/compress/zstd_compress_literals.c
+contrib/python-zstandard/zstd/compress/zstd_compress_literals.h
+contrib/python-zstandard/zstd/compress/zstd_compress_sequences.c
+contrib/python-zstandard/zstd/compress/zstd_compress_sequences.h
 contrib/python-zstandard/zstd/compress/zstd_double_fast.c
 contrib/python-zstandard/zstd/compress/zstd_double_fast.h
 contrib/python-zstandard/zstd/compress/zstd_fast.c

contrib/debugcmdserver.py

@@ -23,6 +23,7 b" if sys.argv[1] == '-':"
 else:
     log = open(sys.argv[1], 'a')
 
+
 def read(size):
     data = sys.stdin.read(size)
     if not data:
@@ -31,6 +32,7 b' def read(size):'
     sys.stdout.flush()
     return data
 
+
 try:
     while True:
         header = read(outputfmtsize)

contrib/debugshell.py

@@ -14,6 +14,7 b' from mercurial import ('
 cmdtable = {}
 command = registrar.command(cmdtable)
 
+
 def pdb(ui, repo, msg, **opts):
     objects = {
         'mercurial': mercurial,
@@ -24,25 +25,25 b' def pdb(ui, repo, msg, **opts):'
 
     code.interact(msg, local=objects)
 
+
 def ipdb(ui, repo, msg, **opts):
     import IPython
 
     cl = repo.changelog
     mf = repo.manifestlog
-    cl, mf # use variables to appease pyflakes
+    cl, mf  # use variables to appease pyflakes
 
     IPython.embed()
 
+
 @command(b'debugshell|dbsh', [])
 def debugshell(ui, repo, **opts):
-    bannermsg = ("loaded repo : %s\n"
-                 "using source: %s" % (pycompat.sysstr(repo.root),
-                                       mercurial.__path__[0]))
+    bannermsg = "loaded repo : %s\n" "using source: %s" % (
+        pycompat.sysstr(repo.root),
+        mercurial.__path__[0],
+    )
 
-    pdbmap = {
-        'pdb'  : 'code',
-        'ipdb' : 'IPython'
-    }
+    pdbmap = {'pdb': 'code', 'ipdb': 'IPython'}
 
     debugger = ui.config(b"ui", b"debugger")
     if not debugger:
@@ -55,8 +56,10 b' def debugshell(ui, repo, **opts):'
         with demandimport.deactivated():
             __import__(pdbmap[debugger])
     except ImportError:
-        ui.warn((b"%s debugger specified but %s module was not found\n")
-                % (debugger, pdbmap[debugger]))
+        ui.warnnoi18n(
+            b"%s debugger specified but %s module was not found\n"
+            % (debugger, pdbmap[debugger])
+        )
         debugger = b'pdb'
 
     getattr(sys.modules[__name__], debugger)(ui, repo, bannermsg, **opts)

contrib/dirstatenonnormalcheck.py

@@ -13,6 +13,7 b' from mercurial import ('
     extensions,
 )
 
+
 def nonnormalentries(dmap):
     """Compute nonnormal entries from dirstate's dmap"""
     res = set()
@@ -21,6 +22,7 b' def nonnormalentries(dmap):'
             res.add(f)
     return res
 
+
 def checkconsistency(ui, orig, dmap, _nonnormalset, label):
     """Compute nonnormalset from dmap, check that it matches _nonnormalset"""
     nonnormalcomputedmap = nonnormalentries(dmap)
@@ -30,15 +32,19 b' def checkconsistency(ui, orig, dmap, _no'
         ui.develwarn(b"[nonnormalset] %s\n" % _nonnormalset, config=b'dirstate')
         ui.develwarn(b"[map] %s\n" % nonnormalcomputedmap, config=b'dirstate')
 
+
 def _checkdirstate(orig, self, arg):
     """Check nonnormal set consistency before and after the call to orig"""
-    checkconsistency(self._ui, orig, self._map, self._map.nonnormalset,
-                     b"before")
+    checkconsistency(
+        self._ui, orig, self._map, self._map.nonnormalset, b"before"
+    )
     r = orig(self, arg)
-    checkconsistency(self._ui, orig, self._map, self._map.nonnormalset,
-                     b"after")
+    checkconsistency(
+        self._ui, orig, self._map, self._map.nonnormalset, b"after"
+    )
     return r
 
+
 def extsetup(ui):
     """Wrap functions modifying dirstate to check nonnormalset consistency"""
     dirstatecl = dirstate.dirstate

contrib/dumprevlog

@@ -22,6 +22,7 b" def binopen(path, mode=b'rb'):"
     if b'b' not in mode:
         mode = mode + b'b'
     return open(path, pycompat.sysstr(mode))
+binopen.options = {}
 
 def printb(data, end=b'\n'):
     sys.stdout.flush()

contrib/fuzz/Makefile

@@ -105,6 +105,33 b' revlog.o: ../../mercurial/cext/revlog.c'
 	  -I../../mercurial \
 	  -c -o revlog.o ../../mercurial/cext/revlog.c
 
+dirs_fuzzer: dirs.cc manifest.o charencode.o parsers.o dirs.o pathencode.o revlog.o pyutil.o
+	$(CXX) $(CXXFLAGS) `$$OUT/sanpy/bin/python-config --cflags` \
+	  -Wno-register -Wno-macro-redefined \
+	  -I../../mercurial dirs.cc \
+	  manifest.o charencode.o parsers.o dirs.o pathencode.o revlog.o pyutil.o \
+	  -lFuzzingEngine `$$OUT/sanpy/bin/python-config --ldflags` \
+	  -o $$OUT/dirs_fuzzer
+
+fncache_fuzzer: fncache.cc manifest.o charencode.o parsers.o dirs.o pathencode.o revlog.o pyutil.o
+	$(CXX) $(CXXFLAGS) `$$OUT/sanpy/bin/python-config --cflags` \
+	  -Wno-register -Wno-macro-redefined \
+	  -I../../mercurial fncache.cc \
+	  manifest.o charencode.o parsers.o dirs.o pathencode.o revlog.o pyutil.o \
+	  -lFuzzingEngine `$$OUT/sanpy/bin/python-config --ldflags` \
+	  -o $$OUT/fncache_fuzzer
+
+jsonescapeu8fast_fuzzer: jsonescapeu8fast.cc manifest.o charencode.o parsers.o dirs.o pathencode.o revlog.o pyutil.o
+	$(CXX) $(CXXFLAGS) `$$OUT/sanpy/bin/python-config --cflags` \
+	  -Wno-register -Wno-macro-redefined \
+	  -I../../mercurial jsonescapeu8fast.cc \
+	  manifest.o charencode.o parsers.o dirs.o pathencode.o revlog.o pyutil.o \
+	  -lFuzzingEngine `$$OUT/sanpy/bin/python-config --ldflags` \
+	  -o $$OUT/jsonescapeu8fast_fuzzer
+
+manifest_corpus.zip:
+	python manifest_corpus.py $$OUT/manifest_fuzzer_seed_corpus.zip
+
 manifest_fuzzer: manifest.cc manifest.o charencode.o parsers.o dirs.o pathencode.o revlog.o pyutil.o
 	$(CXX) $(CXXFLAGS) `$$OUT/sanpy/bin/python-config --cflags` \
 	  -Wno-register -Wno-macro-redefined \
@@ -113,9 +140,6 b' manifest_fuzzer: manifest.cc manifest.o '
 	  -lFuzzingEngine `$$OUT/sanpy/bin/python-config --ldflags` \
 	  -o $$OUT/manifest_fuzzer
 
-manifest_corpus.zip:
-	python manifest_corpus.py $$OUT/manifest_fuzzer_seed_corpus.zip
-
 revlog_fuzzer: revlog.cc manifest.o charencode.o parsers.o dirs.o pathencode.o revlog.o pyutil.o
 	$(CXX) $(CXXFLAGS) `$$OUT/sanpy/bin/python-config --cflags` \
 	  -Wno-register -Wno-macro-redefined \
@@ -155,6 +179,6 b' clean:'
 	  mpatch \
 	  xdiff
 
-oss-fuzz: bdiff_fuzzer mpatch_fuzzer mpatch_corpus.zip xdiff_fuzzer manifest_fuzzer manifest_corpus.zip revlog_fuzzer revlog_corpus.zip dirstate_fuzzer dirstate_corpus.zip fm1readmarkers_fuzzer fm1readmarkers_corpus.zip
+oss-fuzz: bdiff_fuzzer mpatch_fuzzer mpatch_corpus.zip xdiff_fuzzer dirs_fuzzer fncache_fuzzer jsonescapeu8fast_fuzzer manifest_fuzzer manifest_corpus.zip revlog_fuzzer revlog_corpus.zip dirstate_fuzzer dirstate_corpus.zip fm1readmarkers_fuzzer fm1readmarkers_corpus.zip
 
 .PHONY: all clean oss-fuzz

contrib/fuzz/dirstate_corpus.py

@@ -8,8 +8,7 b' ap = argparse.ArgumentParser()'
 ap.add_argument("out", metavar="some.zip", type=str, nargs=1)
 args = ap.parse_args()
 
-reporoot = os.path.normpath(os.path.join(os.path.dirname(__file__),
-                                         '..', '..'))
+reporoot = os.path.normpath(os.path.join(os.path.dirname(__file__), '..', '..'))
 dirstate = os.path.join(reporoot, '.hg', 'dirstate')
 
 with zipfile.ZipFile(args.out[0], "w", zipfile.ZIP_STORED) as zf:

contrib/fuzz/fm1readmarkers_corpus.py

@@ -33,4 +33,6 b' with zipfile.ZipFile(args.out[0], "w", z'
             'nhistedituserAugie Fackler <[e-mail]>\x00\x00\x00yA\xd7\x02'
             'MtA\xd4\xe1\x01,\x00\x00\x01\x03\x03"\xa5\xcb\x86\xb6\xf4\xbaO\xa0'
             'sH\xe7?\xcb\x9b\xc2n\xcfI\x9e\x14\xf0D\xf0!\x18DN\xcd\x97\x016\xa5'
-            '\xef\xa06\xcb\x884\x8a\x03\x01\t\x08\x04\x1fef14operationhisted'))
+            '\xef\xa06\xcb\x884\x8a\x03\x01\t\x08\x04\x1fef14operationhisted'
+        ),
+    )

contrib/fuzz/manifest_corpus.py

@@ -8,8 +8,9 b' ap.add_argument("out", metavar="some.zip'
 args = ap.parse_args()
 
 with zipfile.ZipFile(args.out[0], "w", zipfile.ZIP_STORED) as zf:
-    zf.writestr("manifest_zero",
-'''PKG-INFO\09b3ed8f2b81095a13064402e930565f083346e9a
+    zf.writestr(
+        "manifest_zero",
+        '''PKG-INFO\09b3ed8f2b81095a13064402e930565f083346e9a
 README\080b6e76643dcb44d4bc729e932fc464b3e36dbe3
 hg\0b6444347c629cc058d478023905cfb83b7f5bb9d
 mercurial/__init__.py\0b80de5d138758541c5f05265ad144ab9fa86d1db
@@ -22,9 +23,11 b' mercurial/transaction.py\\09d180df101dc14'
 notes.txt\0703afcec5edb749cf5cec67831f554d6da13f2fb
 setup.py\0ccf3f6daf0f13101ca73631f7a1769e328b472c9
 tkmerge\03c922edb43a9c143682f7bc7b00f98b3c756ebe7
-''')
-    zf.writestr("badmanifest_shorthashes",
-                "narf\0aa\nnarf2\0aaa\n")
-    zf.writestr("badmanifest_nonull",
-                "narf\0cccccccccccccccccccccccccccccccccccccccc\n"
-                "narf2aaaaaaaaaaaaaaaaaaaa\n")
+''',
+    )
+    zf.writestr("badmanifest_shorthashes", "narf\0aa\nnarf2\0aaa\n")
+    zf.writestr(
+        "badmanifest_nonull",
+        "narf\0cccccccccccccccccccccccccccccccccccccccc\n"
+        "narf2aaaaaaaaaaaaaaaaaaaa\n",
+    )

contrib/fuzz/mpatch_corpus.py

@@ -13,6 +13,7 b' ap = argparse.ArgumentParser()'
 ap.add_argument("out", metavar="some.zip", type=str, nargs=1)
 args = ap.parse_args()
 
+
 class deltafrag(object):
     def __init__(self, start, end, data):
         self.start = start
@@ -20,8 +21,11 b' class deltafrag(object):'
         self.data = data
 
     def __str__(self):
-        return struct.pack(
-            ">lll", self.start, self.end, len(self.data)) + self.data
+        return (
+            struct.pack(">lll", self.start, self.end, len(self.data))
+            + self.data
+        )
+
 
 class delta(object):
     def __init__(self, frags):
@@ -30,8 +34,8 b' class delta(object):'
     def __str__(self):
         return ''.join(str(f) for f in self.frags)
 
+
 class corpus(object):
-
     def __init__(self, base, deltas):
         self.base = base
         self.deltas = deltas
@@ -49,19 +53,19 b' class corpus(object):'
         )
         return "".join(parts)
 
+
 with zipfile.ZipFile(args.out[0], "w", zipfile.ZIP_STORED) as zf:
     # Manually constructed entries
     zf.writestr(
-        "one_delta_applies",
-        str(corpus('a', [delta([deltafrag(0, 1, 'b')])]))
+        "one_delta_applies", str(corpus('a', [delta([deltafrag(0, 1, 'b')])]))
     )
     zf.writestr(
         "one_delta_starts_late",
-        str(corpus('a', [delta([deltafrag(3, 1, 'b')])]))
+        str(corpus('a', [delta([deltafrag(3, 1, 'b')])])),
     )
     zf.writestr(
         "one_delta_ends_late",
-        str(corpus('a', [delta([deltafrag(0, 20, 'b')])]))
+        str(corpus('a', [delta([deltafrag(0, 20, 'b')])])),
     )
 
     try:
@@ -70,9 +74,8 b' with zipfile.ZipFile(args.out[0], "w", z'
         fl = r.file('mercurial/manifest.py')
         rl = getattr(fl, '_revlog', fl)
         bins = rl._chunks(rl._deltachain(10)[0])
-        zf.writestr('manifest_py_rev_10',
-                    str(corpus(bins[0], bins[1:])))
-    except: # skip this, so no re-raises
+        zf.writestr('manifest_py_rev_10', str(corpus(bins[0], bins[1:])))
+    except:  # skip this, so no re-raises
         print('skipping seed file from repo data')
     # Automatically discovered by running the fuzzer
     zf.writestr(
@@ -81,7 +84,8 b' with zipfile.ZipFile(args.out[0], "w", z'
     # https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=8876
     zf.writestr(
         "mpatch_ossfuzz_getbe32_ubsan",
-        "\x02\x00\x00\x00\x0c    \xff\xff\xff\xff    ")
+        "\x02\x00\x00\x00\x0c    \xff\xff\xff\xff    ",
+    )
     zf.writestr(
         "mpatch_apply_over_memcpy",
         '\x13\x01\x00\x05\xd0\x00\x00\x00\x00\x00\x00\x00\x00\n \x00\x00\x00'
@@ -342,4 +346,5 b' with zipfile.ZipFile(args.out[0], "w", z'
         '\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
         '\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00se\x00\x00'
         '\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
-        '\x00\x00\x00\x00')
+        '\x00\x00\x00\x00',
+    )

contrib/fuzz/revlog.cc

@@ -20,10 +20,15 b' for inline in (True, False):'
     try:
         index, cache = parse_index2(data, inline)
         index.slicechunktodensity(list(range(len(index))), 0.5, 262144)
+        index.stats()
+        index.findsnapshots({}, 0)
+        10 in index
         for rev in range(len(index)):
+            index.reachableroots(0, [len(index)-1], [rev])
             node = index[rev][7]
             partial = index.shortest(node)
             index.partialmatch(node[:partial])
+            index.deltachain(rev, None, True)
     except Exception as e:
         pass
         # uncomment this print if you're editing this Python code

contrib/fuzz/revlog_corpus.py

@@ -8,13 +8,13 b' ap = argparse.ArgumentParser()'
 ap.add_argument("out", metavar="some.zip", type=str, nargs=1)
 args = ap.parse_args()
 
-reporoot = os.path.normpath(os.path.join(os.path.dirname(__file__),
-                                         '..', '..'))
+reporoot = os.path.normpath(os.path.join(os.path.dirname(__file__), '..', '..'))
 # typically a standalone index
 changelog = os.path.join(reporoot, '.hg', 'store', '00changelog.i')
 # an inline revlog with only a few revisions
 contributing = os.path.join(
-    reporoot, '.hg', 'store', 'data', 'contrib', 'fuzz', 'mpatch.cc.i')
+    reporoot, '.hg', 'store', 'data', 'contrib', 'fuzz', 'mpatch.cc.i'
+)
 
 print(changelog, os.path.exists(changelog))
 print(contributing, os.path.exists(contributing))

contrib/genosxversion.py

@@ -2,27 +2,30 b''
 from __future__ import absolute_import, print_function
 
 import argparse
-import json
 import os
 import subprocess
 import sys
 
 # Always load hg libraries from the hg we can find on $PATH.
-hglib = json.loads(subprocess.check_output(
-    ['hg', 'debuginstall', '-Tjson']))[0]['hgmodules']
+hglib = subprocess.check_output(['hg', 'debuginstall', '-T', '{hgmodules}'])
 sys.path.insert(0, os.path.dirname(hglib))
 
 from mercurial import util
 
 ap = argparse.ArgumentParser()
-ap.add_argument('--paranoid',
-                action='store_true',
-                help=("Be paranoid about how version numbers compare and "
-                      "produce something that's more likely to sort "
-                      "reasonably."))
+ap.add_argument(
+    '--paranoid',
+    action='store_true',
+    help=(
+        "Be paranoid about how version numbers compare and "
+        "produce something that's more likely to sort "
+        "reasonably."
+    ),
+)
 ap.add_argument('--selftest', action='store_true', help='Run self-tests.')
 ap.add_argument('versionfile', help='Path to a valid mercurial __version__.py')
 
+
 def paranoidver(ver):
     """Given an hg version produce something that distutils can sort.
 
@@ -109,22 +112,25 b' def paranoidver(ver):'
         extra = ''
     return '%d.%d.%d%s' % (major, minor, micro, extra)
 
+
 def main(argv):
     opts = ap.parse_args(argv[1:])
     if opts.selftest:
         import doctest
+
         doctest.testmod()
         return
     with open(opts.versionfile) as f:
         for l in f:
             if l.startswith('version = b'):
                 # version number is entire line minus the quotes
-                ver = l[len('version = b') + 1:-2]
+                ver = l[len('version = b') + 1 : -2]
                 break
     if opts.paranoid:
         print(paranoidver(ver))
     else:
         print(ver)
 
+
 if __name__ == '__main__':
     main(sys.argv)

contrib/hgclient.py

@@ -16,17 +16,22 b' if sys.version_info[0] >= 3:'
     stdout = sys.stdout.buffer
     stderr = sys.stderr.buffer
     stringio = io.BytesIO
+
     def bprint(*args):
         # remove b'' as well for ease of test migration
         pargs = [re.sub(br'''\bb(['"])''', br'\1', b'%s' % a) for a in args]
         stdout.write(b' '.join(pargs) + b'\n')
+
+
 else:
     import cStringIO
+
     stdout = sys.stdout
     stderr = sys.stderr
     stringio = cStringIO.StringIO
     bprint = print
 
+
 def connectpipe(path=None, extraargs=()):
     cmdline = [b'hg', b'serve', b'--cmdserver', b'pipe']
     if path:
@@ -38,11 +43,13 b' def connectpipe(path=None, extraargs=())'
             return cmdline
         return [arg.decode("utf-8") for arg in cmdline]
 
-    server = subprocess.Popen(tonative(cmdline), stdin=subprocess.PIPE,
-                              stdout=subprocess.PIPE)
+    server = subprocess.Popen(
+        tonative(cmdline), stdin=subprocess.PIPE, stdout=subprocess.PIPE
+    )
 
     return server
 
+
 class unixconnection(object):
     def __init__(self, sockpath):
         self.sock = sock = socket.socket(socket.AF_UNIX)
@@ -55,6 +62,7 b' class unixconnection(object):'
         self.stdout.close()
         self.sock.close()
 
+
 class unixserver(object):
     def __init__(self, sockpath, logpath=None, repopath=None):
         self.sockpath = sockpath
@@ -80,11 +88,13 b' class unixserver(object):'
         os.kill(self.server.pid, signal.SIGTERM)
         self.server.wait()
 
+
 def writeblock(server, data):
     server.stdin.write(struct.pack(b'>I', len(data)))
     server.stdin.write(data)
     server.stdin.flush()
 
+
 def readchannel(server):
     data = server.stdout.read(5)
     if not data:
@@ -95,11 +105,14 b' def readchannel(server):'
     else:
         return channel, server.stdout.read(length)
 
+
 def sep(text):
     return text.replace(b'\\', b'/')
 
-def runcommand(server, args, output=stdout, error=stderr, input=None,
-               outfilter=lambda x: x):
+
+def runcommand(
+    server, args, output=stdout, error=stderr, input=None, outfilter=lambda x: x
+):
     bprint(b'*** runcommand', b' '.join(args))
     stdout.flush()
     server.stdin.write(b'runcommand\n')
@@ -123,7 +136,7 b' def runcommand(server, args, output=stdo'
         elif ch == b'm':
             bprint(b"message: %r" % data)
         elif ch == b'r':
-            ret, = struct.unpack('>i', data)
+            (ret,) = struct.unpack('>i', data)
             if ret != 0:
                 bprint(b' [%d]' % ret)
             return ret
@@ -132,6 +145,7 b' def runcommand(server, args, output=stdo'
             if ch.isupper():
                 return
 
+
 def check(func, connect=connectpipe):
     stdout.flush()
     server = connect()
@@ -141,7 +155,9 b' def check(func, connect=connectpipe):'
         server.stdin.close()
         server.wait()
 
+
 def checkwith(connect=connectpipe, **kwargs):
     def wrap(func):
         return check(func, lambda: connect(**kwargs))
+
     return wrap

contrib/import-checker.py

@@ -10,7 +10,7 b' import sys'
 # Import a minimal set of stdlib modules needed for list_stdlib_modules()
 # to work when run from a virtualenv.  The modules were chosen empirically
 # so that the return value matches the return value without virtualenv.
-if True: # disable lexical sorting checks
+if True:  # disable lexical sorting checks
     try:
         import BaseHTTPServer as basehttpserver
     except ImportError:
@@ -28,9 +28,12 b' allowsymbolimports = ('
     'mercurial.hgweb.common',
     'mercurial.hgweb.request',
     'mercurial.i18n',
+    'mercurial.interfaces',
     'mercurial.node',
+    'mercurial.pycompat',
     # for revlog to re-export constant to extensions
     'mercurial.revlogutils.constants',
+    'mercurial.revlogutils.flagutil',
     # for cffi modules to re-export pure functions
     'mercurial.pure.base85',
     'mercurial.pure.bdiff',
@@ -45,9 +48,7 b' allowsymbolimports = ('
 )
 
 # Whitelist of symbols that can be directly imported.
-directsymbols = (
-    'demandimport',
-)
+directsymbols = ('demandimport',)
 
 # Modules that must be aliased because they are commonly confused with
 # common variables and can create aliasing and readability issues.
@@ -55,6 +56,7 b' requirealias = {'
     'ui': 'uimod',
 }
 
+
 def usingabsolute(root):
     """Whether absolute imports are being used."""
     if sys.version_info[0] >= 3:
@@ -69,6 +71,7 b' def usingabsolute(root):'
 
     return False
 
+
 def walklocal(root):
     """Recursively yield all descendant nodes but not in a different scope"""
     todo = collections.deque(ast.iter_child_nodes(root))
@@ -80,6 +83,7 b' def walklocal(root):'
             todo.extend(ast.iter_child_nodes(node))
         yield node, newscope
 
+
 def dotted_name_of_path(path):
     """Given a relative path to a source file, return its dotted module name.
 
@@ -89,11 +93,12 b' def dotted_name_of_path(path):'
     'zlib'
     """
     parts = path.replace(os.sep, '/').split('/')
-    parts[-1] = parts[-1].split('.', 1)[0] # remove .py and .so and .ARCH.so
+    parts[-1] = parts[-1].split('.', 1)[0]  # remove .py and .so and .ARCH.so
     if parts[-1].endswith('module'):
         parts[-1] = parts[-1][:-6]
     return '.'.join(parts)
 
+
 def fromlocalfunc(modulename, localmods):
     """Get a function to examine which locally defined module the
     target source imports via a specified name.
@@ -162,6 +167,7 b' def fromlocalfunc(modulename, localmods)'
     prefix = '.'.join(modulename.split('.')[:-1])
     if prefix:
         prefix += '.'
+
     def fromlocal(name, level=0):
         # name is false value when relative imports are used.
         if not name:
@@ -173,8 +179,9 b' def fromlocalfunc(modulename, localmods)'
                 # Check relative name first.
                 candidates = [prefix + name, name]
             else:
-                candidates = ['.'.join(modulename.split('.')[:-level]) +
-                              '.' + name]
+                candidates = [
+                    '.'.join(modulename.split('.')[:-level]) + '.' + name
+                ]
 
         for n in candidates:
             if n in localmods:
@@ -183,18 +190,21 b' def fromlocalfunc(modulename, localmods)'
             if dottedpath in localmods:
                 return (n, dottedpath, True)
         return False
+
     return fromlocal
 
+
 def populateextmods(localmods):
     """Populate C extension modules based on pure modules"""
     newlocalmods = set(localmods)
     for n in localmods:
         if n.startswith('mercurial.pure.'):
-            m = n[len('mercurial.pure.'):]
+            m = n[len('mercurial.pure.') :]
             newlocalmods.add('mercurial.cext.' + m)
             newlocalmods.add('mercurial.cffi._' + m)
     return newlocalmods
 
+
 def list_stdlib_modules():
     """List the modules present in the stdlib.
 
@@ -230,13 +240,13 b' def list_stdlib_modules():'
     for m in ['msvcrt', '_winreg']:
         yield m
     yield '__builtin__'
-    yield 'builtins' # python3 only
-    yield 'importlib.abc' # python3 only
-    yield 'importlib.machinery' # python3 only
-    yield 'importlib.util' # python3 only
+    yield 'builtins'  # python3 only
+    yield 'importlib.abc'  # python3 only
+    yield 'importlib.machinery'  # python3 only
+    yield 'importlib.util'  # python3 only
     for m in 'fcntl', 'grp', 'pwd', 'termios':  # Unix only
         yield m
-    for m in 'cPickle', 'datetime': # in Python (not C) on PyPy
+    for m in 'cPickle', 'datetime':  # in Python (not C) on PyPy
         yield m
     for m in ['cffi']:
         yield m
@@ -262,14 +272,17 b' def list_stdlib_modules():'
     for libpath in sys.path:
         # We want to walk everything in sys.path that starts with something in
         # stdlib_prefixes, but not directories from the hg sources.
-        if (os.path.abspath(libpath).startswith(sourceroot)
-            or not any(libpath.startswith(p) for p in stdlib_prefixes)):
+        if os.path.abspath(libpath).startswith(sourceroot) or not any(
+            libpath.startswith(p) for p in stdlib_prefixes
+        ):
             continue
         for top, dirs, files in os.walk(libpath):
             for i, d in reversed(list(enumerate(dirs))):
-                if (not os.path.exists(os.path.join(top, d, '__init__.py'))
-                    or top == libpath and d in ('hgdemandimport', 'hgext',
-                                                'mercurial')):
+                if (
+                    not os.path.exists(os.path.join(top, d, '__init__.py'))
+                    or top == libpath
+                    and d in ('hgdemandimport', 'hgext', 'mercurial')
+                ):
                     del dirs[i]
             for name in files:
                 if not name.endswith(('.py', '.so', '.pyc', '.pyo', '.pyd')):
@@ -278,12 +291,14 b' def list_stdlib_modules():'
                     full_path = top
                 else:
                     full_path = os.path.join(top, name)
-                rel_path = full_path[len(libpath) + 1:]
+                rel_path = full_path[len(libpath) + 1 :]
                 mod = dotted_name_of_path(rel_path)
                 yield mod
 
+
 stdlib_modules = set(list_stdlib_modules())
 
+
 def imported_modules(source, modulename, f, localmods, ignore_nested=False):
     """Given the source of a file as a string, yield the names
     imported by that file.
@@ -381,6 +396,7 b' def imported_modules(source, modulename,'
                 # lookup
                 yield dottedpath
 
+
 def verify_import_convention(module, source, localmods):
     """Verify imports match our established coding convention.
 
@@ -398,6 +414,7 b' def verify_import_convention(module, sou'
     else:
         return verify_stdlib_on_own_line(root)
 
+
 def verify_modern_convention(module, root, localmods, root_col_offset=0):
     """Verify a file conforms to the modern import convention rules.
 
@@ -441,19 +458,24 b' def verify_modern_convention(module, roo'
     seenlevels = set()
 
     for node, newscope in walklocal(root):
+
         def msg(fmt, *args):
             return (fmt % args, node.lineno)
+
         if newscope:
             # Check for local imports in function
-            for r in verify_modern_convention(module, node, localmods,
-                                              node.col_offset + 4):
+            for r in verify_modern_convention(
+                module, node, localmods, node.col_offset + 4
+            ):
                 yield r
         elif isinstance(node, ast.Import):
             # Disallow "import foo, bar" and require separate imports
             # for each module.
             if len(node.names) > 1:
-                yield msg('multiple imported names: %s',
-                          ', '.join(n.name for n in node.names))
+                yield msg(
+                    'multiple imported names: %s',
+                    ', '.join(n.name for n in node.names),
+                )
 
             name = node.names[0].name
             asname = node.names[0].asname
@@ -463,16 +485,20 b' def verify_modern_convention(module, roo'
             # Ignore sorting rules on imports inside blocks.
             if node.col_offset == root_col_offset:
                 if lastname and name < lastname and laststdlib == stdlib:
-                    yield msg('imports not lexically sorted: %s < %s',
-                              name, lastname)
+                    yield msg(
+                        'imports not lexically sorted: %s < %s', name, lastname
+                    )
 
             lastname = name
             laststdlib = stdlib
 
             # stdlib imports should be before local imports.
             if stdlib and seenlocal and node.col_offset == root_col_offset:
-                yield msg('stdlib import "%s" follows local import: %s',
-                          name, seenlocal)
+                yield msg(
+                    'stdlib import "%s" follows local import: %s',
+                    name,
+                    seenlocal,
+                )
 
             if not stdlib:
                 seenlocal = name
@@ -483,13 +509,16 b' def verify_modern_convention(module, roo'
                 yield msg('import should be relative: %s', name)
 
             if name in requirealias and asname != requirealias[name]:
-                yield msg('%s module must be "as" aliased to %s',
-                          name, requirealias[name])
+                yield msg(
+                    '%s module must be "as" aliased to %s',
+                    name,
+                    requirealias[name],
+                )
 
         elif isinstance(node, ast.ImportFrom):
             # Resolve the full imported module name.
             if node.level > 0:
-                fullname = '.'.join(module.split('.')[:-node.level])
+                fullname = '.'.join(module.split('.')[: -node.level])
                 if node.module:
                     fullname += '.%s' % node.module
             else:
@@ -506,7 +535,8 b' def verify_modern_convention(module, roo'
                 if not fullname or (
                     fullname in stdlib_modules
                     and fullname not in localmods
-                    and fullname + '.__init__' not in localmods):
+                    and fullname + '.__init__' not in localmods
+                ):
                     yield msg('relative import of stdlib module')
                 else:
                     seenlocal = fullname
@@ -516,19 +546,24 b' def verify_modern_convention(module, roo'
             found = fromlocal(node.module, node.level)
             if found and found[2]:  # node.module is a package
                 prefix = found[0] + '.'
-                symbols = (n.name for n in node.names
-                           if not fromlocal(prefix + n.name))
+                symbols = (
+                    n.name for n in node.names if not fromlocal(prefix + n.name)
+                )
             else:
                 symbols = (n.name for n in node.names)
             symbols = [sym for sym in symbols if sym not in directsymbols]
             if node.module and node.col_offset == root_col_offset:
                 if symbols and fullname not in allowsymbolimports:
-                    yield msg('direct symbol import %s from %s',
-                              ', '.join(symbols), fullname)
+                    yield msg(
+                        'direct symbol import %s from %s',
+                        ', '.join(symbols),
+                        fullname,
+                    )
 
                 if symbols and seennonsymbollocal:
-                    yield msg('symbol import follows non-symbol import: %s',
-                              fullname)
+                    yield msg(
+                        'symbol import follows non-symbol import: %s', fullname
+                    )
             if not symbols and fullname not in stdlib_modules:
                 seennonsymbollocal = True
 
@@ -536,15 +571,19 b' def verify_modern_convention(module, roo'
                 assert node.level
 
                 # Only allow 1 group per level.
-                if (node.level in seenlevels
-                    and node.col_offset == root_col_offset):
-                    yield msg('multiple "from %s import" statements',
-                              '.' * node.level)
+                if (
+                    node.level in seenlevels
+                    and node.col_offset == root_col_offset
+                ):
+                    yield msg(
+                        'multiple "from %s import" statements', '.' * node.level
+                    )
 
                 # Higher-level groups come before lower-level groups.
                 if any(node.level > l for l in seenlevels):
-                    yield msg('higher-level import should come first: %s',
-                              fullname)
+                    yield msg(
+                        'higher-level import should come first: %s', fullname
+                    )
 
                 seenlevels.add(node.level)
 
@@ -554,14 +593,23 b' def verify_modern_convention(module, roo'
 
             for n in node.names:
                 if lastentryname and n.name < lastentryname:
-                    yield msg('imports from %s not lexically sorted: %s < %s',
-                              fullname, n.name, lastentryname)
+                    yield msg(
+                        'imports from %s not lexically sorted: %s < %s',
+                        fullname,
+                        n.name,
+                        lastentryname,
+                    )
 
                 lastentryname = n.name
 
                 if n.name in requirealias and n.asname != requirealias[n.name]:
-                    yield msg('%s from %s must be "as" aliased to %s',
-                              n.name, fullname, requirealias[n.name])
+                    yield msg(
+                        '%s from %s must be "as" aliased to %s',
+                        n.name,
+                        fullname,
+                        requirealias[n.name],
+                    )
+
 
 def verify_stdlib_on_own_line(root):
     """Given some python source, verify that stdlib imports are done
@@ -580,13 +628,20 b' def verify_stdlib_on_own_line(root):'
             for n in node.names:
                 from_stdlib[n.name in stdlib_modules].append(n.name)
             if from_stdlib[True] and from_stdlib[False]:
-                yield ('mixed imports\n   stdlib:    %s\n   relative:  %s' %
-                       (', '.join(sorted(from_stdlib[True])),
-                        ', '.join(sorted(from_stdlib[False]))), node.lineno)
+                yield (
+                    'mixed imports\n   stdlib:    %s\n   relative:  %s'
+                    % (
+                        ', '.join(sorted(from_stdlib[True])),
+                        ', '.join(sorted(from_stdlib[False])),
+                    ),
+                    node.lineno,
+                )
+
 
 class CircularImport(Exception):
     pass
 
+
 def checkmod(mod, imports):
     shortest = {}
     visit = [[mod]]
@@ -601,6 +656,7 b' def checkmod(mod, imports):'
                     continue
                 visit.append(path + [i])
 
+
 def rotatecycle(cycle):
     """arrange a cycle so that the lexicographically first module listed first
 
@@ -611,6 +667,7 b' def rotatecycle(cycle):'
     idx = cycle.index(lowest)
     return cycle[idx:] + cycle[:idx] + [lowest]
 
+
 def find_cycles(imports):
     """Find cycles in an already-loaded import graph.
 
@@ -634,9 +691,11 b' def find_cycles(imports):'
             cycles.add(" -> ".join(rotatecycle(cycle)))
     return cycles
 
+
 def _cycle_sortkey(c):
     return len(c), c
 
+
 def embedded(f, modname, src):
     """Extract embedded python code
 
@@ -678,6 +737,7 b' def embedded(f, modname, src):'
             modname = modname.decode('utf8')
         yield code, "%s[%d]" % (modname, starts), name, starts - 1
 
+
 def sources(f, modname):
     """Yields possibly multiple sources from a filepath
 
@@ -698,6 +758,7 b' def sources(f, modname):'
             for script, modname, t, line in embedded(f, modname, src):
                 yield script, modname.encode('utf8'), t, line
 
+
 def main(argv):
     if len(argv) < 2 or (argv[1] == '-' and len(argv) > 2):
         print('Usage: %s {-|file [file] [file] ...}')
@@ -719,15 +780,19 b' def main(argv):'
         for src, modname, name, line in sources(source_path, localmodname):
             try:
                 used_imports[modname] = sorted(
-                    imported_modules(src, modname, name, localmods,
-                                     ignore_nested=True))
-                for error, lineno in verify_import_convention(modname, src,
-                                                              localmods):
+                    imported_modules(
+                        src, modname, name, localmods, ignore_nested=True
+                    )
+                )
+                for error, lineno in verify_import_convention(
+                    modname, src, localmods
+                ):
                     any_errors = True
                     print('%s:%d: %s' % (source_path, lineno + line, error))
             except SyntaxError as e:
-                print('%s:%d: SyntaxError: %s' %
-                      (source_path, e.lineno + line, e))
+                print(
+                    '%s:%d: SyntaxError: %s' % (source_path, e.lineno + line, e)
+                )
     cycles = find_cycles(used_imports)
     if cycles:
         firstmods = set()
@@ -743,5 +808,6 b' def main(argv):'
         any_errors = True
     return any_errors != 0
 
+
 if __name__ == '__main__':
     sys.exit(int(main(sys.argv)))

contrib/install-windows-dependencies.ps1

@@ -37,22 +37,22 b''
 $PYTHON36_x64_URL = "https://www.python.org/ftp/python/3.6.8/python-3.6.8-amd64.exe"
 $PYTHON36_x64_SHA256 = "96088A58B7C43BC83B84E6B67F15E8706C614023DD64F9A5A14E81FF824ADADC"
 
-$PYTHON37_x86_URL = "https://www.python.org/ftp/python/3.7.2/python-3.7.2.exe"
-$PYTHON37_x86_SHA256 = "8BACE330FB409E428B04EEEE083DD9CA7F6C754366D07E23B3853891D8F8C3D0"
-$PYTHON37_x64_URL = "https://www.python.org/ftp/python/3.7.2/python-3.7.2-amd64.exe"
-$PYTHON37_x64_SHA256 = "0FE2A696F5A3E481FED795EF6896ED99157BCEF273EF3C4A96F2905CBDB3AA13"
+$PYTHON37_x86_URL = "https://www.python.org/ftp/python/3.7.4/python-3.7.4.exe"
+$PYTHON37_x86_SHA256 = "9a30ab5568ba37bfbcae5cdee19e9dc30765c42cf066f605221563ff8b20ee34"
+$PYTHON37_X64_URL = "https://www.python.org/ftp/python/3.7.4/python-3.7.4-amd64.exe"
+$PYTHON37_x64_SHA256 = "bab92f987320975c7826171a072bfd64f8f0941aaf2cdeba6924b7025c9968a3"
 
-$PYTHON38_x86_URL = "https://www.python.org/ftp/python/3.8.0/python-3.8.0b2.exe"
-$PYTHON38_x86_SHA256 = "efa37ff7a239332bd5cf8b6e6ff15e3f183da942fd8c8d3e4b6bd11fa5e07e23"
-$PYTHON38_x64_URL = "https://www.python.org/ftp/python/3.8.0/python-3.8.0b2-amd64.exe"
-$PYTHON38_x64_SHA256 = "4e151f7dfa3605e6f400a3b01acfc2517468d71afb1e20f9299149356b79d8e9"
+$PYTHON38_x86_URL = "https://www.python.org/ftp/python/3.8.0/python-3.8.0.exe"
+$PYTHON38_x86_SHA256 = "b471908de5e10d8fb5c3351a5affb1172da7790c533e0c9ffbaeec9c11611b15"
+$PYTHON38_x64_URL = "https://www.python.org/ftp/python/3.8.0/python-3.8.0-amd64.exe"
+$PYTHON38_x64_SHA256 = "a9bbc6088a3e4c7112826e21bfee6277f7b6d93259f7c57176139231bb7071e4"
 
-# PIP 19.0.3.
-$PIP_URL = "https://github.com/pypa/get-pip/raw/fee32c376da1ff6496a798986d7939cd51e1644f/get-pip.py"
-$PIP_SHA256 = "efe99298f3fbb1f56201ce6b81d2658067d2f7d7dfc2d412e0d3cacc9a397c61"
+# PIP 19.2.3.
+$PIP_URL = "https://github.com/pypa/get-pip/raw/309a56c5fd94bd1134053a541cb4657a4e47e09d/get-pip.py"
+$PIP_SHA256 = "57e3643ff19f018f8a00dfaa6b7e4620e3c1a7a2171fd218425366ec006b3bfe"
 
-$VIRTUALENV_URL = "https://files.pythonhosted.org/packages/37/db/89d6b043b22052109da35416abc3c397655e4bd3cff031446ba02b9654fa/virtualenv-16.4.3.tar.gz"
-$VIRTUALENV_SHA256 = "984d7e607b0a5d1329425dd8845bd971b957424b5ba664729fab51ab8c11bc39"
+$VIRTUALENV_URL = "https://files.pythonhosted.org/packages/66/f0/6867af06d2e2f511e4e1d7094ff663acdebc4f15d4a0cb0fed1007395124/virtualenv-16.7.5.tar.gz"
+$VIRTUALENV_SHA256 = "f78d81b62d3147396ac33fc9d77579ddc42cc2a98dd9ea38886f616b33bc7fb2"
 
 $INNO_SETUP_URL = "http://files.jrsoftware.org/is/5/innosetup-5.6.1-unicode.exe"
 $INNO_SETUP_SHA256 = "27D49E9BC769E9D1B214C153011978DB90DC01C2ACD1DDCD9ED7B3FE3B96B538"
@@ -60,9 +60,9 b''
 $MINGW_BIN_URL = "https://osdn.net/frs/redir.php?m=constant&f=mingw%2F68260%2Fmingw-get-0.6.3-mingw32-pre-20170905-1-bin.zip"
 $MINGW_BIN_SHA256 = "2AB8EFD7C7D1FC8EAF8B2FA4DA4EEF8F3E47768284C021599BC7435839A046DF"
 
-$MERCURIAL_WHEEL_FILENAME = "mercurial-4.9-cp27-cp27m-win_amd64.whl"
-$MERCURIAL_WHEEL_URL = "https://files.pythonhosted.org/packages/fe/e8/b872d53dfbbf986bdc46af0b30f580b227fb59bddd2587152a55e205b0cc/$MERCURIAL_WHEEL_FILENAME"
-$MERCURIAL_WHEEL_SHA256 = "218cc2e7c3f1d535007febbb03351663897edf27df0e57d6842e3b686492b429"
+$MERCURIAL_WHEEL_FILENAME = "mercurial-5.1.2-cp27-cp27m-win_amd64.whl"
+$MERCURIAL_WHEEL_URL = "https://files.pythonhosted.org/packages/6d/47/e031e47f7fe9b16e4e3383da47e2b0a7eae6e603996bc67a03ec4fa1b3f4/$MERCURIAL_WHEEL_FILENAME"
+$MERCURIAL_WHEEL_SHA256 = "1d18c7f6ca1456f0f62ee65c9a50c14cbba48ce6e924930cdb10537f5c9eaf5f"
 
 # Writing progress slows down downloads substantially. So disable it.
 $progressPreference = 'silentlyContinue'

contrib/memory.py

@@ -13,6 +13,7 b' prints it to ``stderr`` on exit.'
 
 from __future__ import absolute_import
 
+
 def memusage(ui):
     """Report memory usage of the current process."""
     result = {'peak': 0, 'rss': 0}
@@ -24,8 +25,13 b' def memusage(ui):'
             key = parts[0][2:-1].lower()
             if key in result:
                 result[key] = int(parts[1])
-    ui.write_err(", ".join(["%s: %.1f MiB" % (k, v / 1024.0)
-                            for k, v in result.iteritems()]) + "\n")
+    ui.write_err(
+        ", ".join(
+            ["%s: %.1f MiB" % (k, v / 1024.0) for k, v in result.iteritems()]
+        )
+        + "\n"
+    )
+
 
 def extsetup(ui):
     ui.atexit(memusage, ui)

contrib/packaging/hgpackaging/downloads.py

@@ -98,7 +98,10 b' def secure_download_stream(url, size, sh'
     length = 0
 
     with urllib.request.urlopen(url) as fh:
-        if not url.endswith('.gz') and fh.info().get('Content-Encoding') == 'gzip':
+        if (
+            not url.endswith('.gz')
+            and fh.info().get('Content-Encoding') == 'gzip'
+        ):
             fh = gzip.GzipFile(fileobj=fh)
 
         while True:
@@ -114,12 +117,14 b' def secure_download_stream(url, size, sh'
     digest = h.hexdigest()
 
     if length != size:
-        raise IntegrityError('size mismatch on %s: wanted %d; got %d' % (
-            url, size, length))
+        raise IntegrityError(
+            'size mismatch on %s: wanted %d; got %d' % (url, size, length)
+        )
 
     if digest != sha256:
-        raise IntegrityError('sha256 mismatch on %s: wanted %s; got %s' % (
-            url, sha256, digest))
+        raise IntegrityError(
+            'sha256 mismatch on %s: wanted %s; got %s' % (url, sha256, digest)
+        )
 
 
 def download_to_path(url: str, path: pathlib.Path, size: int, sha256: str):
@@ -162,12 +167,14 b' def download_to_path(url: str, path: pat'
     print('successfully downloaded %s' % url)
 
 
-def download_entry(name: dict, dest_path: pathlib.Path, local_name=None) -> pathlib.Path:
+def download_entry(
+    name: dict, dest_path: pathlib.Path, local_name=None
+) -> pathlib.Path:
     entry = DOWNLOADS[name]
 
     url = entry['url']
 
-    local_name = local_name or url[url.rindex('/') + 1:]
+    local_name = local_name or url[url.rindex('/') + 1 :]
 
     local_path = dest_path / local_name
     download_to_path(url, local_path, entry['size'], entry['sha256'])

contrib/packaging/hgpackaging/inno.py

@@ -12,12 +12,8 b' import pathlib'
 import shutil
 import subprocess
 
-from .py2exe import (
-    build_py2exe,
-)
-from .util import (
-    find_vc_runtime_files,
-)
+from .py2exe import build_py2exe
+from .util import find_vc_runtime_files
 
 
 EXTRA_PACKAGES = {
@@ -28,9 +24,13 b' EXTRA_PACKAGES = {'
 }
 
 
-def build(source_dir: pathlib.Path, build_dir: pathlib.Path,
-          python_exe: pathlib.Path, iscc_exe: pathlib.Path,
-          version=None):
+def build(
+    source_dir: pathlib.Path,
+    build_dir: pathlib.Path,
+    python_exe: pathlib.Path,
+    iscc_exe: pathlib.Path,
+    version=None,
+):
     """Build the Inno installer.
 
     Build files will be placed in ``build_dir``.
@@ -44,11 +44,18 b' def build(source_dir: pathlib.Path, buil'
 
     vc_x64 = r'\x64' in os.environ.get('LIB', '')
 
-    requirements_txt = (source_dir / 'contrib' / 'packaging' /
-                        'inno' / 'requirements.txt')
+    requirements_txt = (
+        source_dir / 'contrib' / 'packaging' / 'inno' / 'requirements.txt'
+    )
 
-    build_py2exe(source_dir, build_dir, python_exe, 'inno',
-                 requirements_txt, extra_packages=EXTRA_PACKAGES)
+    build_py2exe(
+        source_dir,
+        build_dir,
+        python_exe,
+        'inno',
+        requirements_txt,
+        extra_packages=EXTRA_PACKAGES,
+    )
 
     # hg.exe depends on VC9 runtime DLLs. Copy those into place.
     for f in find_vc_runtime_files(vc_x64):

contrib/packaging/hgpackaging/py2exe.py

@@ -11,9 +11,7 b' import os'
 import pathlib
 import subprocess
 
-from .downloads import (
-    download_entry,
-)
+from .downloads import download_entry
 from .util import (
     extract_tar_to_directory,
     extract_zip_to_directory,
@@ -21,12 +19,17 b' from .util import ('
 )
 
 
-def build_py2exe(source_dir: pathlib.Path, build_dir: pathlib.Path,
-                 python_exe: pathlib.Path, build_name: str,
-                 venv_requirements_txt: pathlib.Path,
-                 extra_packages=None, extra_excludes=None,
-                 extra_dll_excludes=None,
-                 extra_packages_script=None):
+def build_py2exe(
+    source_dir: pathlib.Path,
+    build_dir: pathlib.Path,
+    python_exe: pathlib.Path,
+    build_name: str,
+    venv_requirements_txt: pathlib.Path,
+    extra_packages=None,
+    extra_excludes=None,
+    extra_dll_excludes=None,
+    extra_packages_script=None,
+):
     """Build Mercurial with py2exe.
 
     Build files will be placed in ``build_dir``.
@@ -36,9 +39,11 b' def build_py2exe(source_dir: pathlib.Pat'
     to already be configured with an active toolchain.
     """
     if 'VCINSTALLDIR' not in os.environ:
-        raise Exception('not running from a Visual C++ build environment; '
-                        'execute the "Visual C++ <version> Command Prompt" '
-                        'application shortcut or a vcsvarsall.bat file')
+        raise Exception(
+            'not running from a Visual C++ build environment; '
+            'execute the "Visual C++ <version> Command Prompt" '
+            'application shortcut or a vcsvarsall.bat file'
+        )
 
     # Identity x86/x64 and validate the environment matches the Python
     # architecture.
@@ -48,12 +53,16 b' def build_py2exe(source_dir: pathlib.Pat'
 
     if vc_x64:
         if py_info['arch'] != '64bit':
-            raise Exception('architecture mismatch: Visual C++ environment '
-                            'is configured for 64-bit but Python is 32-bit')
+            raise Exception(
+                'architecture mismatch: Visual C++ environment '
+                'is configured for 64-bit but Python is 32-bit'
+            )
     else:
         if py_info['arch'] != '32bit':
-            raise Exception('architecture mismatch: Visual C++ environment '
-                            'is configured for 32-bit but Python is 64-bit')
+            raise Exception(
+                'architecture mismatch: Visual C++ environment '
+                'is configured for 32-bit but Python is 64-bit'
+            )
 
     if py_info['py3']:
         raise Exception('Only Python 2 is currently supported')
@@ -65,11 +74,11 b' def build_py2exe(source_dir: pathlib.Pat'
     virtualenv_pkg, virtualenv_entry = download_entry('virtualenv', build_dir)
     py2exe_pkg, py2exe_entry = download_entry('py2exe', build_dir)
 
-    venv_path = build_dir / ('venv-%s-%s' % (build_name,
-                                             'x64' if vc_x64 else 'x86'))
+    venv_path = build_dir / (
+        'venv-%s-%s' % (build_name, 'x64' if vc_x64 else 'x86')
+    )
 
-    gettext_root = build_dir / (
-        'gettext-win-%s' % gettext_entry['version'])
+    gettext_root = build_dir / ('gettext-win-%s' % gettext_entry['version'])
 
     if not gettext_root.exists():
         extract_zip_to_directory(gettext_pkg, gettext_root)
@@ -77,7 +86,8 b' def build_py2exe(source_dir: pathlib.Pat'
 
     # This assumes Python 2. We don't need virtualenv on Python 3.
     virtualenv_src_path = build_dir / (
-        'virtualenv-%s' % virtualenv_entry['version'])
+        'virtualenv-%s' % virtualenv_entry['version']
+    )
     virtualenv_py = virtualenv_src_path / 'virtualenv.py'
 
     if not virtualenv_src_path.exists():
@@ -91,14 +101,15 b' def build_py2exe(source_dir: pathlib.Pat'
     if not venv_path.exists():
         print('creating virtualenv with dependencies')
         subprocess.run(
-            [str(python_exe), str(virtualenv_py), str(venv_path)],
-            check=True)
+            [str(python_exe), str(virtualenv_py), str(venv_path)], check=True
+        )
 
     venv_python = venv_path / 'Scripts' / 'python.exe'
     venv_pip = venv_path / 'Scripts' / 'pip.exe'
 
-    subprocess.run([str(venv_pip), 'install', '-r', str(venv_requirements_txt)],
-                   check=True)
+    subprocess.run(
+        [str(venv_pip), 'install', '-r', str(venv_requirements_txt)], check=True
+    )
 
     # Force distutils to use VC++ settings from environment, which was
     # validated above.
@@ -107,9 +118,13 b' def build_py2exe(source_dir: pathlib.Pat'
     env['MSSdk'] = '1'
 
     if extra_packages_script:
-        more_packages = set(subprocess.check_output(
-            extra_packages_script,
-            cwd=build_dir).split(b'\0')[-1].strip().decode('utf-8').splitlines())
+        more_packages = set(
+            subprocess.check_output(extra_packages_script, cwd=build_dir)
+            .split(b'\0')[-1]
+            .strip()
+            .decode('utf-8')
+            .splitlines()
+        )
         if more_packages:
             if not extra_packages:
                 extra_packages = more_packages
@@ -119,32 +134,38 b' def build_py2exe(source_dir: pathlib.Pat'
     if extra_packages:
         env['HG_PY2EXE_EXTRA_PACKAGES'] = ' '.join(sorted(extra_packages))
         hgext3rd_extras = sorted(
-            e for e in extra_packages if e.startswith('hgext3rd.'))
+            e for e in extra_packages if e.startswith('hgext3rd.')
+        )
         if hgext3rd_extras:
             env['HG_PY2EXE_EXTRA_INSTALL_PACKAGES'] = ' '.join(hgext3rd_extras)
     if extra_excludes:
         env['HG_PY2EXE_EXTRA_EXCLUDES'] = ' '.join(sorted(extra_excludes))
     if extra_dll_excludes:
         env['HG_PY2EXE_EXTRA_DLL_EXCLUDES'] = ' '.join(
-            sorted(extra_dll_excludes))
+            sorted(extra_dll_excludes)
+        )
 
     py2exe_py_path = venv_path / 'Lib' / 'site-packages' / 'py2exe'
     if not py2exe_py_path.exists():
         print('building py2exe')
-        subprocess.run([str(venv_python), 'setup.py', 'install'],
-                       cwd=py2exe_source_path,
-                       env=env,
-                       check=True)
+        subprocess.run(
+            [str(venv_python), 'setup.py', 'install'],
+            cwd=py2exe_source_path,
+            env=env,
+            check=True,
+        )
 
     # Register location of msgfmt and other binaries.
     env['PATH'] = '%s%s%s' % (
-        env['PATH'], os.pathsep, str(gettext_root / 'bin'))
+        env['PATH'],
+        os.pathsep,
+        str(gettext_root / 'bin'),
+    )
 
     print('building Mercurial')
     subprocess.run(
-        [str(venv_python), 'setup.py',
-         'py2exe',
-         'build_doc', '--html'],
+        [str(venv_python), 'setup.py', 'py2exe', 'build_doc', '--html'],
         cwd=str(source_dir),
         env=env,
-        check=True)
+        check=True,
+    )

contrib/packaging/hgpackaging/util.py

@@ -32,8 +32,11 b' def find_vc_runtime_files(x64=False):'
 
     prefix = 'amd64' if x64 else 'x86'
 
-    candidates = sorted(p for p in os.listdir(winsxs)
-                  if p.lower().startswith('%s_microsoft.vc90.crt_' % prefix))
+    candidates = sorted(
+        p
+        for p in os.listdir(winsxs)
+        if p.lower().startswith('%s_microsoft.vc90.crt_' % prefix)
+    )
 
     for p in candidates:
         print('found candidate VC runtime: %s' % p)
@@ -72,7 +75,7 b' def windows_10_sdk_info():'
         'version': version,
         'bin_root': bin_version,
         'bin_x86': bin_version / 'x86',
-        'bin_x64': bin_version / 'x64'
+        'bin_x64': bin_version / 'x64',
     }
 
 
@@ -89,9 +92,14 b' def find_signtool():'
     raise Exception('could not find signtool.exe in Windows 10 SDK')
 
 
-def sign_with_signtool(file_path, description, subject_name=None,
-                       cert_path=None, cert_password=None,
-                       timestamp_url=None):
+def sign_with_signtool(
+    file_path,
+    description,
+    subject_name=None,
+    cert_path=None,
+    cert_password=None,
+    timestamp_url=None,
+):
     """Digitally sign a file with signtool.exe.
 
     ``file_path`` is file to sign.
@@ -114,10 +122,13 b' def sign_with_signtool(file_path, descri'
         cert_password = getpass.getpass('password for %s: ' % cert_path)
 
     args = [
-        str(find_signtool()), 'sign',
+        str(find_signtool()),
+        'sign',
         '/v',
-        '/fd', 'sha256',
-        '/d', description,
+        '/fd',
+        'sha256',
+        '/d',
+        description,
     ]
 
     if cert_path:

contrib/packaging/hgpackaging/wix.py

@@ -15,12 +15,8 b' import tempfile'
 import typing
 import xml.dom.minidom
 
-from .downloads import (
-    download_entry,
-)
-from .py2exe import (
-    build_py2exe,
-)
+from .downloads import download_entry
+from .py2exe import build_py2exe
 from .util import (
     extract_zip_to_directory,
     sign_with_signtool,
@@ -84,17 +80,29 b' def normalize_version(version):'
 
 def ensure_vc90_merge_modules(build_dir):
     x86 = (
-        download_entry('vc9-crt-x86-msm', build_dir,
-                       local_name='microsoft.vcxx.crt.x86_msm.msm')[0],
-        download_entry('vc9-crt-x86-msm-policy', build_dir,
-                       local_name='policy.x.xx.microsoft.vcxx.crt.x86_msm.msm')[0]
+        download_entry(
+            'vc9-crt-x86-msm',
+            build_dir,
+            local_name='microsoft.vcxx.crt.x86_msm.msm',
+        )[0],
+        download_entry(
+            'vc9-crt-x86-msm-policy',
+            build_dir,
+            local_name='policy.x.xx.microsoft.vcxx.crt.x86_msm.msm',
+        )[0],
     )
 
     x64 = (
-        download_entry('vc9-crt-x64-msm', build_dir,
-                       local_name='microsoft.vcxx.crt.x64_msm.msm')[0],
-        download_entry('vc9-crt-x64-msm-policy', build_dir,
-                       local_name='policy.x.xx.microsoft.vcxx.crt.x64_msm.msm')[0]
+        download_entry(
+            'vc9-crt-x64-msm',
+            build_dir,
+            local_name='microsoft.vcxx.crt.x64_msm.msm',
+        )[0],
+        download_entry(
+            'vc9-crt-x64-msm-policy',
+            build_dir,
+            local_name='policy.x.xx.microsoft.vcxx.crt.x64_msm.msm',
+        )[0],
     )
     return {
         'x86': x86,
@@ -116,17 +124,26 b' def run_candle(wix, cwd, wxs, source_dir'
     subprocess.run(args, cwd=str(cwd), check=True)
 
 
-def make_post_build_signing_fn(name, subject_name=None, cert_path=None,
-                               cert_password=None, timestamp_url=None):
+def make_post_build_signing_fn(
+    name,
+    subject_name=None,
+    cert_path=None,
+    cert_password=None,
+    timestamp_url=None,
+):
     """Create a callable that will use signtool to sign hg.exe."""
 
     def post_build_sign(source_dir, build_dir, dist_dir, version):
         description = '%s %s' % (name, version)
 
-        sign_with_signtool(dist_dir / 'hg.exe', description,
-                           subject_name=subject_name, cert_path=cert_path,
-                           cert_password=cert_password,
-                           timestamp_url=timestamp_url)
+        sign_with_signtool(
+            dist_dir / 'hg.exe',
+            description,
+            subject_name=subject_name,
+            cert_path=cert_path,
+            cert_password=cert_password,
+            timestamp_url=timestamp_url,
+        )
 
     return post_build_sign
 
@@ -155,7 +172,8 b' def make_libraries_xml(wix_dir: pathlib.'
     # We can't use ElementTree because it doesn't handle the
     # <?include ?> directives.
     doc = xml.dom.minidom.parseString(
-        LIBRARIES_XML.format(wix_dir=str(wix_dir)))
+        LIBRARIES_XML.format(wix_dir=str(wix_dir))
+    )
 
     component = doc.getElementsByTagName('Component')[0]
 
@@ -177,11 +195,16 b' def make_libraries_xml(wix_dir: pathlib.'
     return doc.toprettyxml()
 
 
-def build_installer(source_dir: pathlib.Path, python_exe: pathlib.Path,
-                    msi_name='mercurial', version=None, post_build_fn=None,
-                    extra_packages_script=None,
-                    extra_wxs:typing.Optional[typing.Dict[str,str]]=None,
-                    extra_features:typing.Optional[typing.List[str]]=None):
+def build_installer(
+    source_dir: pathlib.Path,
+    python_exe: pathlib.Path,
+    msi_name='mercurial',
+    version=None,
+    post_build_fn=None,
+    extra_packages_script=None,
+    extra_wxs: typing.Optional[typing.Dict[str, str]] = None,
+    extra_features: typing.Optional[typing.List[str]] = None,
+):
     """Build a WiX MSI installer.
 
     ``source_dir`` is the path to the Mercurial source tree to use.
@@ -209,10 +232,15 b' def build_installer(source_dir: pathlib.'
 
     requirements_txt = wix_dir / 'requirements.txt'
 
-    build_py2exe(source_dir, hg_build_dir,
-                 python_exe, 'wix', requirements_txt,
-                 extra_packages=EXTRA_PACKAGES,
-                 extra_packages_script=extra_packages_script)
+    build_py2exe(
+        source_dir,
+        hg_build_dir,
+        python_exe,
+        'wix',
+        requirements_txt,
+        extra_packages=EXTRA_PACKAGES,
+        extra_packages_script=extra_packages_script,
+    )
 
     version = version or normalize_version(find_version(source_dir))
     print('using version string: %s' % version)
@@ -265,16 +293,19 b' def build_installer(source_dir: pathlib.'
 
     run_candle(wix_path, build_dir, source, source_build_rel, defines=defines)
 
-    msi_path = source_dir / 'dist' / (
-        '%s-%s-%s.msi' % (msi_name, version, arch))
+    msi_path = (
+        source_dir / 'dist' / ('%s-%s-%s.msi' % (msi_name, version, arch))
+    )
 
     args = [
         str(wix_path / 'light.exe'),
         '-nologo',
-        '-ext', 'WixUIExtension',
+        '-ext',
+        'WixUIExtension',
         '-sw1076',
         '-spdb',
-        '-o', str(msi_path),
+        '-o',
+        str(msi_path),
     ]
 
     for source, rel_path in SUPPORT_WXS:
@@ -286,10 +317,12 b' def build_installer(source_dir: pathlib.'
         source = os.path.basename(source)
         args.append(str(build_dir / ('%s.wixobj' % source[:-4])))
 
-    args.extend([
-        str(build_dir / 'library.wixobj'),
-        str(build_dir / 'mercurial.wixobj'),
-    ])
+    args.extend(
+        [
+            str(build_dir / 'library.wixobj'),
+            str(build_dir / 'mercurial.wixobj'),
+        ]
+    )
 
     subprocess.run(args, cwd=str(source_dir), check=True)
 
@@ -300,11 +333,19 b' def build_installer(source_dir: pathlib.'
     }
 
 
-def build_signed_installer(source_dir: pathlib.Path, python_exe: pathlib.Path,
-                           name: str, version=None, subject_name=None,
-                           cert_path=None, cert_password=None,
-                           timestamp_url=None, extra_packages_script=None,
-                           extra_wxs=None, extra_features=None):
+def build_signed_installer(
+    source_dir: pathlib.Path,
+    python_exe: pathlib.Path,
+    name: str,
+    version=None,
+    subject_name=None,
+    cert_path=None,
+    cert_password=None,
+    timestamp_url=None,
+    extra_packages_script=None,
+    extra_wxs=None,
+    extra_features=None,
+):
     """Build an installer with signed executables."""
 
     post_build_fn = make_post_build_signing_fn(
@@ -312,16 +353,27 b' def build_signed_installer(source_dir: p'
         subject_name=subject_name,
         cert_path=cert_path,
         cert_password=cert_password,
-        timestamp_url=timestamp_url)
+        timestamp_url=timestamp_url,
+    )
 
-    info = build_installer(source_dir, python_exe=python_exe,
-                           msi_name=name.lower(), version=version,
-                           post_build_fn=post_build_fn,
-                           extra_packages_script=extra_packages_script,
-                           extra_wxs=extra_wxs, extra_features=extra_features)
+    info = build_installer(
+        source_dir,
+        python_exe=python_exe,
+        msi_name=name.lower(),
+        version=version,
+        post_build_fn=post_build_fn,
+        extra_packages_script=extra_packages_script,
+        extra_wxs=extra_wxs,
+        extra_features=extra_features,
+    )
 
     description = '%s %s' % (name, version)
 
-    sign_with_signtool(info['msi_path'], description,
-                       subject_name=subject_name, cert_path=cert_path,
-                       cert_password=cert_password, timestamp_url=timestamp_url)
+    sign_with_signtool(
+        info['msi_path'],
+        description,
+        subject_name=subject_name,
+        cert_path=cert_path,
+        cert_password=cert_password,
+        timestamp_url=timestamp_url,
+    )

contrib/packaging/inno/build.py

@@ -19,14 +19,15 b' import sys'
 if __name__ == '__main__':
     parser = argparse.ArgumentParser()
 
-    parser.add_argument('--python',
-                        required=True,
-                        help='path to python.exe to use')
-    parser.add_argument('--iscc',
-                        help='path to iscc.exe to use')
-    parser.add_argument('--version',
-                        help='Mercurial version string to use '
-                             '(detected from __version__.py if not defined')
+    parser.add_argument(
+        '--python', required=True, help='path to python.exe to use'
+    )
+    parser.add_argument('--iscc', help='path to iscc.exe to use')
+    parser.add_argument(
+        '--version',
+        help='Mercurial version string to use '
+        '(detected from __version__.py if not defined',
+    )
 
     args = parser.parse_args()
 
@@ -36,8 +37,11 b" if __name__ == '__main__':"
     if args.iscc:
         iscc = pathlib.Path(args.iscc)
     else:
-        iscc = (pathlib.Path(os.environ['ProgramFiles(x86)']) / 'Inno Setup 5' /
-            'ISCC.exe')
+        iscc = (
+            pathlib.Path(os.environ['ProgramFiles(x86)'])
+            / 'Inno Setup 5'
+            / 'ISCC.exe'
+        )
 
     here = pathlib.Path(os.path.abspath(os.path.dirname(__file__)))
     source_dir = here.parent.parent.parent
@@ -47,5 +51,10 b" if __name__ == '__main__':"
 
     from hgpackaging.inno import build
 
-    build(source_dir, build_dir, pathlib.Path(args.python), iscc,
-          version=args.version)
+    build(
+        source_dir,
+        build_dir,
+        pathlib.Path(args.python),
+        iscc,
+        version=args.version,
+    )

contrib/packaging/wix/build.py

@@ -17,31 +17,42 b' import sys'
 if __name__ == '__main__':
     parser = argparse.ArgumentParser()
 
-    parser.add_argument('--name',
-                        help='Application name',
-                        default='Mercurial')
-    parser.add_argument('--python',
-                        help='Path to Python executable to use',
-                        required=True)
-    parser.add_argument('--sign-sn',
-                        help='Subject name (or fragment thereof) of certificate '
-                             'to use for signing')
-    parser.add_argument('--sign-cert',
-                        help='Path to certificate to use for signing')
-    parser.add_argument('--sign-password',
-                        help='Password for signing certificate')
-    parser.add_argument('--sign-timestamp-url',
-                        help='URL of timestamp server to use for signing')
-    parser.add_argument('--version',
-                        help='Version string to use')
-    parser.add_argument('--extra-packages-script',
-                        help=('Script to execute to include extra packages in '
-                              'py2exe binary.'))
-    parser.add_argument('--extra-wxs',
-                        help='CSV of path_to_wxs_file=working_dir_for_wxs_file')
-    parser.add_argument('--extra-features',
-                        help=('CSV of extra feature names to include '
-                              'in the installer from the extra wxs files'))
+    parser.add_argument('--name', help='Application name', default='Mercurial')
+    parser.add_argument(
+        '--python', help='Path to Python executable to use', required=True
+    )
+    parser.add_argument(
+        '--sign-sn',
+        help='Subject name (or fragment thereof) of certificate '
+        'to use for signing',
+    )
+    parser.add_argument(
+        '--sign-cert', help='Path to certificate to use for signing'
+    )
+    parser.add_argument(
+        '--sign-password', help='Password for signing certificate'
+    )
+    parser.add_argument(
+        '--sign-timestamp-url',
+        help='URL of timestamp server to use for signing',
+    )
+    parser.add_argument('--version', help='Version string to use')
+    parser.add_argument(
+        '--extra-packages-script',
+        help=(
+            'Script to execute to include extra packages in ' 'py2exe binary.'
+        ),
+    )
+    parser.add_argument(
+        '--extra-wxs', help='CSV of path_to_wxs_file=working_dir_for_wxs_file'
+    )
+    parser.add_argument(
+        '--extra-features',
+        help=(
+            'CSV of extra feature names to include '
+            'in the installer from the extra wxs files'
+        ),
+    )
 
     args = parser.parse_args()
 
@@ -69,7 +80,8 b" if __name__ == '__main__':"
         kwargs['extra_packages_script'] = args.extra_packages_script
     if args.extra_wxs:
         kwargs['extra_wxs'] = dict(
-            thing.split("=") for thing in args.extra_wxs.split(','))
+            thing.split("=") for thing in args.extra_wxs.split(',')
+        )
     if args.extra_features:
         kwargs['extra_features'] = args.extra_features.split(',')
 

contrib/perf-utils/perf-revlog-write-plot.py

@@ -44,18 +44,12 b' def plot(data, title=None):'
     comb_plt = fig.add_subplot(211)
     other_plt = fig.add_subplot(212)
 
-    comb_plt.plot(ary[0],
-                  np.cumsum(ary[1]),
-                  color='red',
-                  linewidth=1,
-                  label='comb')
+    comb_plt.plot(
+        ary[0], np.cumsum(ary[1]), color='red', linewidth=1, label='comb'
+    )
 
     plots = []
-    p = other_plt.plot(ary[0],
-                       ary[1],
-                       color='red',
-                       linewidth=1,
-                       label='wall')
+    p = other_plt.plot(ary[0], ary[1], color='red', linewidth=1, label='wall')
     plots.append(p)
 
     colors = {
@@ -64,20 +58,24 b' def plot(data, title=None):'
         1000: ('purple', 'xkcd:dark pink'),
     }
     for n, color in colors.items():
-        avg_n = np.convolve(ary[1], np.full(n, 1. / n), 'valid')
-        p = other_plt.plot(ary[0][n - 1:],
-                           avg_n,
-                           color=color[0],
-                           linewidth=1,
-                           label='avg time last %d' % n)
+        avg_n = np.convolve(ary[1], np.full(n, 1.0 / n), 'valid')
+        p = other_plt.plot(
+            ary[0][n - 1 :],
+            avg_n,
+            color=color[0],
+            linewidth=1,
+            label='avg time last %d' % n,
+        )
         plots.append(p)
 
         med_n = scipy.signal.medfilt(ary[1], n + 1)
-        p = other_plt.plot(ary[0],
-                           med_n,
-                           color=color[1],
-                           linewidth=1,
-                           label='median time last %d' % n)
+        p = other_plt.plot(
+            ary[0],
+            med_n,
+            color=color[1],
+            linewidth=1,
+            label='median time last %d' % n,
+        )
         plots.append(p)
 
     formatter = mticker.ScalarFormatter()
@@ -108,6 +106,7 b' def plot(data, title=None):'
         else:
             legline.set_alpha(0.2)
         fig.canvas.draw()
+
     if title is not None:
         fig.canvas.set_window_title(title)
     fig.canvas.mpl_connect('pick_event', onpick)