git: skeleton of a new extension to _directly_ operate on git repos

This is based in part of work I did years ago in hgit, but it's mostly
new code since I'm using pygit2 instead of dulwich and the hg storage
interfaces have improved. Some cleanup of old hgit code by Pulkit,
which I greatly appreciate.

test-git-interop.t does not cover a whole lot of cases, but it
passes. It includes status, diff, making a new commit, and `hg annotate`
working on the git repository.

This is _not_ (yet) production quality code: this is an
experiment. Known technical debt lurking in this implementation:

 * Writing bookmarks just totally ignores transactions.
 * The way progress is threaded down into the gitstore is awful.
 * Ideally we'd find a way to incrementally reindex DAGs. I'm not sure
   how to do that efficiently, so we might need a "known only fast-forwards"
   mode on the DAG indexer for use on `hg commit` and friends.
 * We don't even _try_ to do anything reasonable for `hg pull` or `hg push`.
 * Mercurial need an interface for the changelog type.

Tests currently require git 2.24 as far as I'm aware: `git status` has
some changed output that I didn't try and handle in a compatible way.

This patch has produced some interesting cleanups, most recently on
the manifest type. I expect continuing down this road will produce
other meritorious cleanups throughout our code.

Differential Revision: https://phab.mercurial-scm.org/D6734

hgext/git/TODO.md

@@ -0,0 +1,39 b''
+Octopus Merge Support
+=====================
+
+This will be moderately complicated, as we'll need to synthesize phony
+changeset entries to explode the octopus into "revisions" that only
+have two parents each. For today, we can probably just do something like
+
+    aaaaaaaaaaaaaaaaaaXX{20 bytes of exploded node's hex sha}
+
+where XX is a counter (so we could have as many as 255 parents in a
+git commit - more than I think we'd ever see.) That means that we can
+install some check in this extension to disallow checking out or
+otherwise interacting with the `aaaaaaaaaaaaaaaaaa` revisions.
+
+
+Interface Creation
+====================
+
+We at least need an interface definition for `changelog` in core that
+this extension can satisfy, and again for `basicstore`.
+
+
+Reason About Locking
+====================
+
+We should spend some time thinking hard about locking, especially on
+.git/index etc. We're probably adequately locking the _git_
+repository, but may not have enough locking correctness in places
+where hg does locking that git isn't aware of (notably the working
+copy, which I believe Git does not lock.)
+
+Clean up requirements
+=====================
+
+Right now (for historical reasons, mainly) hgext.git uses a
+.hg/this-is-git file to detect repositories that should be treated as
+git. We should look in the .hg/requires for the "git" requirement
+instead (we already set this requirement, so it's mostly keying off
+that instead of using an empty file.)

hgext/git/__init__.py

@@ -0,0 +1,259 b''
+"""grant Mercurial the ability to operate on Git repositories. (EXPERIMENTAL)
+
+This is currently super experimental. It probably will consume your
+firstborn a la Rumpelstiltskin, etc.
+"""
+
+from __future__ import absolute_import
+
+import os
+
+import pygit2
+
+from mercurial.i18n import _
+
+from mercurial import (
+    commands,
+    error,
+    extensions,
+    localrepo,
+    pycompat,
+    store,
+    util,
+)
+
+from . import (
+    dirstate,
+    gitlog,
+    gitutil,
+    index,
+)
+
+
+# TODO: extract an interface for this in core
+class gitstore(object):  # store.basicstore):
+    def __init__(self, path, vfstype):
+        self.vfs = vfstype(path)
+        self.path = self.vfs.base
+        self.createmode = store._calcmode(self.vfs)
+        # above lines should go away in favor of:
+        # super(gitstore, self).__init__(path, vfstype)
+
+        self.git = pygit2.Repository(
+            os.path.normpath(os.path.join(path, b'..', b'.git'))
+        )
+        self._progress_factory = lambda *args, **kwargs: None
+
+    @util.propertycache
+    def _db(self):
+        # We lazy-create the database because we want to thread a
+        # progress callback down to the indexing process if it's
+        # required, and we don't have a ui handle in makestore().
+        return index.get_index(self.git, self._progress_factory)
+
+    def join(self, f):
+        """Fake store.join method for git repositories.
+
+        For the most part, store.join is used for @storecache
+        decorators to invalidate caches when various files
+        change. We'll map the ones we care about, and ignore the rest.
+        """
+        if f in (b'00changelog.i', b'00manifest.i'):
+            # This is close enough: in order for the changelog cache
+            # to be invalidated, HEAD will have to change.
+            return os.path.join(self.path, b'HEAD')
+        elif f == b'lock':
+            # TODO: we probably want to map this to a git lock, I
+            # suspect index.lock. We should figure out what the
+            # most-alike file is in git-land. For now we're risking
+            # bad concurrency errors if another git client is used.
+            return os.path.join(self.path, b'hgit-bogus-lock')
+        elif f in (b'obsstore', b'phaseroots', b'narrowspec', b'bookmarks'):
+            return os.path.join(self.path, b'..', b'.hg', f)
+        raise NotImplementedError(b'Need to pick file for %s.' % f)
+
+    def changelog(self, trypending):
+        # TODO we don't have a plan for trypending in hg's git support yet
+        return gitlog.changelog(self.git, self._db)
+
+    def manifestlog(self, repo, storenarrowmatch):
+        # TODO handle storenarrowmatch and figure out if we need the repo arg
+        return gitlog.manifestlog(self.git, self._db)
+
+    def invalidatecaches(self):
+        pass
+
+    def write(self, tr=None):
+        # normally this handles things like fncache writes, which we don't have
+        pass
+
+
+def _makestore(orig, requirements, storebasepath, vfstype):
+    if os.path.exists(
+        os.path.join(storebasepath, b'this-is-git')
+    ) and os.path.exists(os.path.join(storebasepath, b'..', b'.git')):
+        return gitstore(storebasepath, vfstype)
+    return orig(requirements, storebasepath, vfstype)
+
+
+class gitfilestorage(object):
+    def file(self, path):
+        if path[0:1] == b'/':
+            path = path[1:]
+        return gitlog.filelog(self.store.git, self.store._db, path)
+
+
+def _makefilestorage(orig, requirements, features, **kwargs):
+    store = kwargs['store']
+    if isinstance(store, gitstore):
+        return gitfilestorage
+    return orig(requirements, features, **kwargs)
+
+
+def _setupdothg(ui, path):
+    dothg = os.path.join(path, b'.hg')
+    if os.path.exists(dothg):
+        ui.warn(_(b'git repo already initialized for hg\n'))
+    else:
+        os.mkdir(os.path.join(path, b'.hg'))
+        # TODO is it ok to extend .git/info/exclude like this?
+        with open(
+            os.path.join(path, b'.git', b'info', b'exclude'), 'ab'
+        ) as exclude:
+            exclude.write(b'\n.hg\n')
+    with open(os.path.join(dothg, b'this-is-git'), 'wb') as f:
+        pass
+    with open(os.path.join(dothg, b'requirements'), 'wb') as f:
+        f.write(b'git\n')
+
+
+_BMS_PREFIX = 'refs/heads/'
+
+
+class gitbmstore(object):
+    def __init__(self, gitrepo):
+        self.gitrepo = gitrepo
+
+    def __contains__(self, name):
+        return (
+            _BMS_PREFIX + pycompat.fsdecode(name)
+        ) in self.gitrepo.references
+
+    def __iter__(self):
+        for r in self.gitrepo.listall_references():
+            if r.startswith(_BMS_PREFIX):
+                yield pycompat.fsencode(r[len(_BMS_PREFIX) :])
+
+    def __getitem__(self, k):
+        return (
+            self.gitrepo.references[_BMS_PREFIX + pycompat.fsdecode(k)]
+            .peel()
+            .id.raw
+        )
+
+    def get(self, k, default=None):
+        try:
+            if k in self:
+                return self[k]
+            return default
+        except pygit2.InvalidSpecError:
+            return default
+
+    @property
+    def active(self):
+        h = self.gitrepo.references['HEAD']
+        if not isinstance(h.target, str) or not h.target.startswith(
+            _BMS_PREFIX
+        ):
+            return None
+        return pycompat.fsencode(h.target[len(_BMS_PREFIX) :])
+
+    @active.setter
+    def active(self, mark):
+        raise NotImplementedError
+
+    def names(self, node):
+        r = []
+        for ref in self.gitrepo.listall_references():
+            if not ref.startswith(_BMS_PREFIX):
+                continue
+            if self.gitrepo.references[ref].peel().id.raw != node:
+                continue
+            r.append(pycompat.fsencode(ref[len(_BMS_PREFIX) :]))
+        return r
+
+    # Cleanup opportunity: this is *identical* to core's bookmarks store.
+    def expandname(self, bname):
+        if bname == b'.':
+            if self.active:
+                return self.active
+            raise error.RepoLookupError(_(b"no active bookmark"))
+        return bname
+
+    def applychanges(self, repo, tr, changes):
+        """Apply a list of changes to bookmarks
+        """
+        # TODO: this should respect transactions, but that's going to
+        # require enlarging the gitbmstore to know how to do in-memory
+        # temporary writes and read those back prior to transaction
+        # finalization.
+        for name, node in changes:
+            if node is None:
+                self.gitrepo.references.delete(
+                    _BMS_PREFIX + pycompat.fsdecode(name)
+                )
+            else:
+                self.gitrepo.references.create(
+                    _BMS_PREFIX + pycompat.fsdecode(name),
+                    gitutil.togitnode(node),
+                    force=True,
+                )
+
+
+def init(orig, ui, dest=b'.', **opts):
+    if opts.get('git', False):
+        path = os.path.abspath(dest)
+        # TODO: walk up looking for the git repo
+        _setupdothg(ui, path)
+        return 0
+    return orig(ui, dest=dest, **opts)
+
+
+def reposetup(ui, repo):
+    if isinstance(repo.store, gitstore):
+        orig = repo.__class__
+        repo.store._progress_factory = repo.ui.makeprogress
+
+        class gitlocalrepo(orig):
+            def _makedirstate(self):
+                # TODO narrow support here
+                return dirstate.gitdirstate(
+                    self.ui, self.vfs.base, self.store.git
+                )
+
+            def commit(self, *args, **kwargs):
+                ret = orig.commit(self, *args, **kwargs)
+                tid = self.store.git[gitutil.togitnode(ret)].tree.id
+                # DANGER! This will flush any writes staged to the
+                # index in Git, but we're sidestepping the index in a
+                # way that confuses git when we commit. Alas.
+                self.store.git.index.read_tree(tid)
+                self.store.git.index.write()
+                return ret
+
+            @property
+            def _bookmarks(self):
+                return gitbmstore(self.store.git)
+
+        repo.__class__ = gitlocalrepo
+    return repo
+
+
+def extsetup(ui):
+    extensions.wrapfunction(localrepo, b'makestore', _makestore)
+    extensions.wrapfunction(localrepo, b'makefilestorage', _makefilestorage)
+    # Inject --git flag for `hg init`
+    entry = extensions.wrapcommand(commands.table, b'init', init)
+    entry[1].extend(
+        [(b'', b'git', None, b'setup up a git repository instead of hg')]
+    )

hgext/git/dirstate.py

@@ -0,0 +1,295 b''
+from __future__ import absolute_import
+
+import contextlib
+import errno
+import os
+
+import pygit2
+
+from mercurial import (
+    error,
+    extensions,
+    match as matchmod,
+    node as nodemod,
+    pycompat,
+    scmutil,
+    util,
+)
+from mercurial.interfaces import (
+    dirstate as intdirstate,
+    util as interfaceutil,
+)
+
+from . import gitutil
+
+
+def readpatternfile(orig, filepath, warn, sourceinfo=False):
+    if not (b'info/exclude' in filepath or filepath.endswith(b'.gitignore')):
+        return orig(filepath, warn, sourceinfo=False)
+    result = []
+    warnings = []
+    with open(filepath, b'rb') as fp:
+        for l in fp:
+            l = l.strip()
+            if not l or l.startswith(b'#'):
+                continue
+            if l.startswith(b'!'):
+                warnings.append(b'unsupported ignore pattern %s' % l)
+                continue
+            if l.startswith(b'/'):
+                result.append(b'rootglob:' + l[1:])
+            else:
+                result.append(b'relglob:' + l)
+    return result, warnings
+
+
+extensions.wrapfunction(matchmod, b'readpatternfile', readpatternfile)
+
+
+_STATUS_MAP = {
+    pygit2.GIT_STATUS_CONFLICTED: b'm',
+    pygit2.GIT_STATUS_CURRENT: b'n',
+    pygit2.GIT_STATUS_IGNORED: b'?',
+    pygit2.GIT_STATUS_INDEX_DELETED: b'r',
+    pygit2.GIT_STATUS_INDEX_MODIFIED: b'n',
+    pygit2.GIT_STATUS_INDEX_NEW: b'a',
+    pygit2.GIT_STATUS_INDEX_RENAMED: b'a',
+    pygit2.GIT_STATUS_INDEX_TYPECHANGE: b'n',
+    pygit2.GIT_STATUS_WT_DELETED: b'r',
+    pygit2.GIT_STATUS_WT_MODIFIED: b'n',
+    pygit2.GIT_STATUS_WT_NEW: b'?',
+    pygit2.GIT_STATUS_WT_RENAMED: b'a',
+    pygit2.GIT_STATUS_WT_TYPECHANGE: b'n',
+    pygit2.GIT_STATUS_WT_UNREADABLE: b'?',
+    pygit2.GIT_STATUS_INDEX_MODIFIED | pygit2.GIT_STATUS_WT_MODIFIED: 'm',
+}
+
+
[e-mail](intdirstate.idirstate)
+class gitdirstate(object):
+    def __init__(self, ui, root, gitrepo):
+        self._ui = ui
+        self._root = os.path.dirname(root)
+        self.git = gitrepo
+        self._plchangecallbacks = {}
+
+    def p1(self):
+        return self.git.head.peel().id.raw
+
+    def p2(self):
+        # TODO: MERGE_HEAD? something like that, right?
+        return nodemod.nullid
+
+    def setparents(self, p1, p2=nodemod.nullid):
+        assert p2 == nodemod.nullid, b'TODO merging support'
+        self.git.head.set_target(gitutil.togitnode(p1))
+
+    @util.propertycache
+    def identity(self):
+        return util.filestat.frompath(
+            os.path.join(self._root, b'.git', b'index')
+        )
+
+    def branch(self):
+        return b'default'
+
+    def parents(self):
+        # TODO how on earth do we find p2 if a merge is in flight?
+        return self.p1(), nodemod.nullid
+
+    def __iter__(self):
+        return (pycompat.fsencode(f.path) for f in self.git.index)
+
+    def items(self):
+        for ie in self.git.index:
+            yield ie.path, None  # value should be a dirstatetuple
+
+    # py2,3 compat forward
+    iteritems = items
+
+    def __getitem__(self, filename):
+        try:
+            gs = self.git.status_file(filename)
+        except KeyError:
+            return b'?'
+        return _STATUS_MAP[gs]
+
+    def __contains__(self, filename):
+        try:
+            gs = self.git.status_file(filename)
+            return _STATUS_MAP[gs] != b'?'
+        except KeyError:
+            return False
+
+    def status(self, match, subrepos, ignored, clean, unknown):
+        # TODO handling of clean files - can we get that from git.status()?
+        modified, added, removed, deleted, unknown, ignored, clean = (
+            [],
+            [],
+            [],
+            [],
+            [],
+            [],
+            [],
+        )
+        gstatus = self.git.status()
+        for path, status in gstatus.items():
+            path = pycompat.fsencode(path)
+            if status == pygit2.GIT_STATUS_IGNORED:
+                if path.endswith(b'/'):
+                    continue
+                ignored.append(path)
+            elif status in (
+                pygit2.GIT_STATUS_WT_MODIFIED,
+                pygit2.GIT_STATUS_INDEX_MODIFIED,
+                pygit2.GIT_STATUS_WT_MODIFIED
+                | pygit2.GIT_STATUS_INDEX_MODIFIED,
+            ):
+                modified.append(path)
+            elif status == pygit2.GIT_STATUS_INDEX_NEW:
+                added.append(path)
+            elif status == pygit2.GIT_STATUS_WT_NEW:
+                unknown.append(path)
+            elif status == pygit2.GIT_STATUS_WT_DELETED:
+                deleted.append(path)
+            elif status == pygit2.GIT_STATUS_INDEX_DELETED:
+                removed.append(path)
+            else:
+                raise error.Abort(
+                    b'unhandled case: status for %r is %r' % (path, status)
+                )
+
+        # TODO are we really always sure of status here?
+        return (
+            False,
+            scmutil.status(
+                modified, added, removed, deleted, unknown, ignored, clean
+            ),
+        )
+
+    def flagfunc(self, buildfallback):
+        # TODO we can do better
+        return buildfallback()
+
+    def getcwd(self):
+        # TODO is this a good way to do this?
+        return os.path.dirname(
+            os.path.dirname(pycompat.fsencode(self.git.path))
+        )
+
+    def normalize(self, path):
+        normed = util.normcase(path)
+        assert normed == path, b"TODO handling of case folding: %s != %s" % (
+            normed,
+            path,
+        )
+        return path
+
+    @property
+    def _checklink(self):
+        return util.checklink(os.path.dirname(pycompat.fsencode(self.git.path)))
+
+    def copies(self):
+        # TODO support copies?
+        return {}
+
+    # # TODO what the heck is this
+    _filecache = set()
+
+    def pendingparentchange(self):
+        # TODO: we need to implement the context manager bits and
+        # correctly stage/revert index edits.
+        return False
+
+    def write(self, tr):
+        # TODO: call parent change callbacks
+
+        if tr:
+
+            def writeinner(category):
+                self.git.index.write()
+
+            tr.addpending(b'gitdirstate', writeinner)
+        else:
+            self.git.index.write()
+
+    def pathto(self, f, cwd=None):
+        if cwd is None:
+            cwd = self.getcwd()
+        # TODO core dirstate does something about slashes here
+        assert isinstance(f, bytes)
+        r = util.pathto(self._root, cwd, f)
+        return r
+
+    def matches(self, match):
+        for x in self.git.index:
+            p = pycompat.fsencode(x.path)
+            if match(p):
+                yield p
+
+    def normal(self, f, parentfiledata=None):
+        """Mark a file normal and clean."""
+        # TODO: for now we just let libgit2 re-stat the file. We can
+        # clearly do better.
+
+    def normallookup(self, f):
+        """Mark a file normal, but possibly dirty."""
+        # TODO: for now we just let libgit2 re-stat the file. We can
+        # clearly do better.
+
+    def walk(self, match, subrepos, unknown, ignored, full=True):
+        # TODO: we need to use .status() and not iterate the index,
+        # because the index doesn't force a re-walk and so `hg add` of
+        # a new file without an intervening call to status will
+        # silently do nothing.
+        r = {}
+        cwd = self.getcwd()
+        for path, status in self.git.status().items():
+            if path.startswith('.hg/'):
+                continue
+            path = pycompat.fsencode(path)
+            if not match(path):
+                continue
+            # TODO construct the stat info from the status object?
+            try:
+                s = os.stat(os.path.join(cwd, path))
+            except OSError as e:
+                if e.errno != errno.ENOENT:
+                    raise
+                continue
+            r[path] = s
+        return r
+
+    def savebackup(self, tr, backupname):
+        # TODO: figure out a strategy for saving index backups.
+        pass
+
+    def restorebackup(self, tr, backupname):
+        # TODO: figure out a strategy for saving index backups.
+        pass
+
+    def add(self, f):
+        self.git.index.add(pycompat.fsdecode(f))
+
+    def drop(self, f):
+        self.git.index.remove(pycompat.fsdecode(f))
+
+    def remove(self, f):
+        self.git.index.remove(pycompat.fsdecode(f))
+
+    def copied(self, path):
+        # TODO: track copies?
+        return None
+
+    @contextlib.contextmanager
+    def parentchange(self):
+        # TODO: track this maybe?
+        yield
+
+    def addparentchangecallback(self, category, callback):
+        # TODO: should this be added to the dirstate interface?
+        self._plchangecallbacks[category] = callback
+
+    def clearbackup(self, tr, backupname):
+        # TODO
+        pass

hgext/git/gitlog.py

@@ -0,0 +1,463 b''
+from __future__ import absolute_import
+
+import pygit2
+
+from mercurial.i18n import _
+
+from mercurial import (
+    ancestor,
+    changelog as hgchangelog,
+    dagop,
+    encoding,
+    error,
+    manifest,
+    node as nodemod,
+    pycompat,
+)
+from mercurial.interfaces import (
+    repository,
+    util as interfaceutil,
+)
+from mercurial.utils import stringutil
+from . import (
+    gitutil,
+    index,
+    manifest as gitmanifest,
+)
+
+
+class baselog(object):  # revlog.revlog):
+    """Common implementations between changelog and manifestlog."""
+
+    def __init__(self, gr, db):
+        self.gitrepo = gr
+        self._db = db
+
+    def __len__(self):
+        return int(
+            self._db.execute('SELECT COUNT(*) FROM changelog').fetchone()[0]
+        )
+
+    def rev(self, n):
+        if n == nodemod.nullid:
+            return -1
+        t = self._db.execute(
+            'SELECT rev FROM changelog WHERE node = ?', (gitutil.togitnode(n),)
+        ).fetchone()
+        if t is None:
+            raise error.LookupError(n, b'00changelog.i', _(b'no node %d'))
+        return t[0]
+
+    def node(self, r):
+        if r == nodemod.nullrev:
+            return nodemod.nullid
+        t = self._db.execute(
+            'SELECT node FROM changelog WHERE rev = ?', (r,)
+        ).fetchone()
+        if t is None:
+            raise error.LookupError(r, b'00changelog.i', _(b'no node'))
+        return nodemod.bin(t[0])
+
+    def hasnode(self, n):
+        t = self._db.execute(
+            'SELECT node FROM changelog WHERE node = ?', (n,)
+        ).fetchone()
+        return t is not None
+
+
+class baselogindex(object):
+    def __init__(self, log):
+        self._log = log
+
+    def has_node(self, n):
+        return self._log.rev(n) != -1
+
+    def __len__(self):
+        return len(self._log)
+
+    def __getitem__(self, idx):
+        p1rev, p2rev = self._log.parentrevs(idx)
+        # TODO: it's messy that the index leaks so far out of the
+        # storage layer that we have to implement things like reading
+        # this raw tuple, which exposes revlog internals.
+        return (
+            # Pretend offset is just the index, since we don't really care.
+            idx,
+            # Same with lengths
+            idx,  # length
+            idx,  # rawsize
+            -1,  # delta base
+            idx,  # linkrev TODO is this right?
+            p1rev,
+            p2rev,
+            self._log.node(idx),
+        )
+
+
+# TODO: an interface for the changelog type?
+class changelog(baselog):
+    def __contains__(self, rev):
+        try:
+            self.node(rev)
+            return True
+        except error.LookupError:
+            return False
+
+    @property
+    def filteredrevs(self):
+        # TODO: we should probably add a refs/hg/ namespace for hidden
+        # heads etc, but that's an idea for later.
+        return set()
+
+    @property
+    def index(self):
+        return baselogindex(self)
+
+    @property
+    def nodemap(self):
+        r = {
+            nodemod.bin(v[0]): v[1]
+            for v in self._db.execute('SELECT node, rev FROM changelog')
+        }
+        r[nodemod.nullid] = nodemod.nullrev
+        return r
+
+    def tip(self):
+        t = self._db.execute(
+            'SELECT node FROM changelog ORDER BY rev DESC LIMIT 1'
+        ).fetchone()
+        if t:
+            return nodemod.bin(t[0])
+        return nodemod.nullid
+
+    def revs(self, start=0, stop=None):
+        if stop is None:
+            stop = self.tip()
+        t = self._db.execute(
+            'SELECT rev FROM changelog '
+            'WHERE rev >= ? AND rev <= ? '
+            'ORDER BY REV ASC',
+            (start, stop),
+        )
+        return (int(r[0]) for r in t)
+
+    def _partialmatch(self, id):
+        if nodemod.wdirhex.startswith(id):
+            raise error.WdirUnsupported
+        candidates = [
+            nodemod.bin(x[0])
+            for x in self._db.execute(
+                'SELECT node FROM changelog WHERE node LIKE ?', (id + b'%',)
+            )
+        ]
+        if nodemod.nullhex.startswith(id):
+            candidates.append(nodemod.nullid)
+        if len(candidates) > 1:
+            raise error.AmbiguousPrefixLookupError(
+                id, b'00changelog.i', _(b'ambiguous identifier')
+            )
+        if candidates:
+            return candidates[0]
+        return None
+
+    def flags(self, rev):
+        return 0
+
+    def shortest(self, node, minlength=1):
+        nodehex = nodemod.hex(node)
+        for attempt in pycompat.xrange(minlength, len(nodehex) + 1):
+            candidate = nodehex[:attempt]
+            matches = int(
+                self._db.execute(
+                    'SELECT COUNT(*) FROM changelog WHERE node LIKE ?',
+                    (pycompat.sysstr(nodehex + b'%'),),
+                ).fetchone()[0]
+            )
+            if matches == 1:
+                return candidate
+        return nodehex
+
+    def headrevs(self, revs=None):
+        realheads = [
+            int(x[0])
+            for x in self._db.execute(
+                'SELECT rev FROM changelog '
+                'INNER JOIN heads ON changelog.node = heads.node'
+            )
+        ]
+        if revs:
+            return sorted([r for r in revs if r in realheads])
+        return sorted(realheads)
+
+    def changelogrevision(self, nodeorrev):
+        # Ensure we have a node id
+        if isinstance(nodeorrev, int):
+            n = self.node(nodeorrev)
+        else:
+            n = nodeorrev
+        # handle looking up nullid
+        if n == nodemod.nullid:
+            return hgchangelog._changelogrevision(extra={})
+        hn = gitutil.togitnode(n)
+        # We've got a real commit!
+        files = [
+            r[0]
+            for r in self._db.execute(
+                'SELECT filename FROM changedfiles '
+                'WHERE node = ? and filenode != ?',
+                (hn, gitutil.nullgit),
+            )
+        ]
+        filesremoved = [
+            r[0]
+            for r in self._db.execute(
+                'SELECT filename FROM changedfiles '
+                'WHERE node = ? and filenode = ?',
+                (hn, nodemod.nullhex),
+            )
+        ]
+        c = self.gitrepo[hn]
+        return hgchangelog._changelogrevision(
+            manifest=n,  # pretend manifest the same as the commit node
+            user=b'%s <%s>'
+            % (c.author.name.encode('utf8'), c.author.email.encode('utf8')),
+            date=(c.author.time, -c.author.offset * 60),
+            files=files,
+            # TODO filesadded in the index
+            filesremoved=filesremoved,
+            description=c.message.encode('utf8'),
+            # TODO do we want to handle extra? how?
+            extra={b'branch': b'default'},
+        )
+
+    def ancestors(self, revs, stoprev=0, inclusive=False):
+        revs = list(revs)
+        tip = self.rev(self.tip())
+        for r in revs:
+            if r > tip:
+                raise IndexError(b'Invalid rev %r' % r)
+        return ancestor.lazyancestors(
+            self.parentrevs, revs, stoprev=stoprev, inclusive=inclusive
+        )
+
+    # Cleanup opportunity: this is *identical* to the revlog.py version
+    def descendants(self, revs):
+        return dagop.descendantrevs(revs, self.revs, self.parentrevs)
+
+    def reachableroots(self, minroot, heads, roots, includepath=False):
+        return dagop._reachablerootspure(
+            self.parentrevs, minroot, roots, heads, includepath
+        )
+
+    # Cleanup opportunity: this is *identical* to the revlog.py version
+    def isancestor(self, a, b):
+        a, b = self.rev(a), self.rev(b)
+        return self.isancestorrev(a, b)
+
+    # Cleanup opportunity: this is *identical* to the revlog.py version
+    def isancestorrev(self, a, b):
+        if a == nodemod.nullrev:
+            return True
+        elif a == b:
+            return True
+        elif a > b:
+            return False
+        return bool(self.reachableroots(a, [b], [a], includepath=False))
+
+    def parentrevs(self, rev):
+        n = self.node(rev)
+        hn = gitutil.togitnode(n)
+        c = self.gitrepo[hn]
+        p1 = p2 = nodemod.nullrev
+        if c.parents:
+            p1 = self.rev(c.parents[0].id.raw)
+            if len(c.parents) > 2:
+                raise error.Abort(b'TODO octopus merge handling')
+            if len(c.parents) == 2:
+                p2 = self.rev(c.parents[0].id.raw)
+        return p1, p2
+
+    # Private method is used at least by the tags code.
+    _uncheckedparentrevs = parentrevs
+
+    def commonancestorsheads(self, a, b):
+        # TODO the revlog verson of this has a C path, so we probably
+        # need to optimize this...
+        a, b = self.rev(a), self.rev(b)
+        return [
+            self.node(n)
+            for n in ancestor.commonancestorsheads(self.parentrevs, a, b)
+        ]
+
+    def branchinfo(self, rev):
+        """Git doesn't do named branches, so just put everything on default."""
+        return b'default', False
+
+    def delayupdate(self, tr):
+        # TODO: I think we can elide this because we're just dropping
+        # an object in the git repo?
+        pass
+
+    def add(
+        self,
+        manifest,
+        files,
+        desc,
+        transaction,
+        p1,
+        p2,
+        user,
+        date=None,
+        extra=None,
+        p1copies=None,
+        p2copies=None,
+        filesadded=None,
+        filesremoved=None,
+    ):
+        parents = []
+        hp1, hp2 = gitutil.togitnode(p1), gitutil.togitnode(p2)
+        if p1 != nodemod.nullid:
+            parents.append(hp1)
+        if p2 and p2 != nodemod.nullid:
+            parents.append(hp2)
+        assert date is not None
+        timestamp, tz = date
+        sig = pygit2.Signature(
+            encoding.unifromlocal(stringutil.person(user)),
+            encoding.unifromlocal(stringutil.email(user)),
+            timestamp,
+            -(tz // 60),
+        )
+        oid = self.gitrepo.create_commit(
+            None, sig, sig, desc, gitutil.togitnode(manifest), parents
+        )
+        # Set up an internal reference to force the commit into the
+        # changelog. Hypothetically, we could even use this refs/hg/
+        # namespace to allow for anonymous heads on git repos, which
+        # would be neat.
+        self.gitrepo.references.create(
+            'refs/hg/internal/latest-commit', oid, force=True
+        )
+        # Reindex now to pick up changes. We omit the progress
+        # callback because this will be very quick.
+        index._index_repo(self.gitrepo, self._db)
+        return oid.raw
+
+
+class manifestlog(baselog):
+    def __getitem__(self, node):
+        return self.get(b'', node)
+
+    def get(self, relpath, node):
+        if node == nodemod.nullid:
+            # TODO: this should almost certainly be a memgittreemanifestctx
+            return manifest.memtreemanifestctx(self, relpath)
+        commit = self.gitrepo[gitutil.togitnode(node)]
+        t = commit.tree
+        if relpath:
+            parts = relpath.split(b'/')
+            for p in parts:
+                te = t[p]
+                t = self.gitrepo[te.id]
+        return gitmanifest.gittreemanifestctx(self.gitrepo, t)
+
+
[e-mail](repository.ifilestorage)
+class filelog(baselog):
+    def __init__(self, gr, db, path):
+        super(filelog, self).__init__(gr, db)
+        assert isinstance(path, bytes)
+        self.path = path
+
+    def read(self, node):
+        if node == nodemod.nullid:
+            return b''
+        return self.gitrepo[gitutil.togitnode(node)].data
+
+    def lookup(self, node):
+        if len(node) not in (20, 40):
+            node = int(node)
+        if isinstance(node, int):
+            assert False, b'todo revnums for nodes'
+        if len(node) == 40:
+            node = nodemod.bin(node)
+        hnode = gitutil.togitnode(node)
+        if hnode in self.gitrepo:
+            return node
+        raise error.LookupError(self.path, node, _(b'no match found'))
+
+    def cmp(self, node, text):
+        """Returns True if text is different than content at `node`."""
+        return self.read(node) != text
+
+    def add(self, text, meta, transaction, link, p1=None, p2=None):
+        assert not meta  # Should we even try to handle this?
+        return self.gitrepo.create_blob(text).raw
+
+    def __iter__(self):
+        for clrev in self._db.execute(
+            '''
+SELECT rev FROM changelog
+INNER JOIN changedfiles ON changelog.node = changedfiles.node
+WHERE changedfiles.filename = ? AND changedfiles.filenode != ?
+        ''',
+            (pycompat.fsdecode(self.path), gitutil.nullgit),
+        ):
+            yield clrev[0]
+
+    def linkrev(self, fr):
+        return fr
+
+    def rev(self, node):
+        row = self._db.execute(
+            '''
+SELECT rev FROM changelog
+INNER JOIN changedfiles ON changelog.node = changedfiles.node
+WHERE changedfiles.filename = ? AND changedfiles.filenode = ?''',
+            (pycompat.fsdecode(self.path), gitutil.togitnode(node)),
+        ).fetchone()
+        if row is None:
+            raise error.LookupError(self.path, node, _(b'no such node'))
+        return int(row[0])
+
+    def node(self, rev):
+        maybe = self._db.execute(
+            '''SELECT filenode FROM changedfiles
+INNER JOIN changelog ON changelog.node = changedfiles.node
+WHERE changelog.rev = ? AND filename = ?
+''',
+            (rev, pycompat.fsdecode(self.path)),
+        ).fetchone()
+        if maybe is None:
+            raise IndexError('gitlog %r out of range %d' % (self.path, rev))
+        return nodemod.bin(maybe[0])
+
+    def parents(self, node):
+        gn = gitutil.togitnode(node)
+        gp = pycompat.fsdecode(self.path)
+        ps = []
+        for p in self._db.execute(
+            '''SELECT p1filenode, p2filenode FROM changedfiles
+WHERE filenode = ? AND filename = ?
+''',
+            (gn, gp),
+        ).fetchone():
+            if p is None:
+                commit = self._db.execute(
+                    "SELECT node FROM changedfiles "
+                    "WHERE filenode = ? AND filename = ?",
+                    (gn, gp),
+                ).fetchone()[0]
+                # This filelog is missing some data. Build the
+                # filelog, then recurse (which will always find data).
+                if pycompat.ispy3:
+                    commit = commit.decode('ascii')
+                index.fill_in_filelog(self.gitrepo, self._db, commit, gp, gn)
+                return self.parents(node)
+            else:
+                ps.append(nodemod.bin(p))
+        return ps
+
+    def renamed(self, node):
+        # TODO: renames/copies
+        return False

hgext/git/gitutil.py

@@ -0,0 +1,26 b''
+"""utilities to assist in working with pygit2"""
+from __future__ import absolute_import
+
+from mercurial.node import bin, hex, nullid
+
+from mercurial import pycompat
+
+
+def togitnode(n):
+    """Wrapper to convert a Mercurial binary node to a unicode hexlified node.
+
+    pygit2 and sqlite both need nodes as strings, not bytes.
+    """
+    assert len(n) == 20
+    return pycompat.sysstr(hex(n))
+
+
+def fromgitnode(n):
+    """Opposite of togitnode."""
+    assert len(n) == 40
+    if pycompat.ispy3:
+        return bin(n.encode('ascii'))
+    return bin(n)
+
+
+nullgit = togitnode(nullid)

hgext/git/index.py

@@ -0,0 +1,346 b''
+from __future__ import absolute_import
+
+import collections
+import os
+import sqlite3
+
+import pygit2
+
+from mercurial.i18n import _
+
+from mercurial import (
+    encoding,
+    error,
+    node as nodemod,
+    pycompat,
+)
+
+from . import gitutil
+
+
+_CURRENT_SCHEMA_VERSION = 1
+_SCHEMA = (
+    """
+CREATE TABLE refs (
+  -- node and name are unique together. There may be more than one name for
+  -- a given node, and there may be no name at all for a given node (in the
+  -- case of an anonymous hg head).
+  node TEXT NOT NULL,
+  name TEXT
+);
+
+-- The "possible heads" of the repository, which we use to figure out
+-- if we need to re-walk the changelog.
+CREATE TABLE possible_heads (
+  node TEXT NOT NULL
+);
+
+-- The topological heads of the changelog, which hg depends on.
+CREATE TABLE heads (
+  node TEXT NOT NULL
+);
+
+-- A total ordering of the changelog
+CREATE TABLE changelog (
+  rev INTEGER NOT NULL PRIMARY KEY,
+  node TEXT NOT NULL,
+  p1 TEXT,
+  p2 TEXT
+);
+
+CREATE UNIQUE INDEX changelog_node_idx ON changelog(node);
+CREATE UNIQUE INDEX changelog_node_rev_idx ON changelog(rev, node);
+
+-- Changed files for each commit, which lets us dynamically build
+-- filelogs.
+CREATE TABLE changedfiles (
+  node TEXT NOT NULL,
+  filename TEXT NOT NULL,
+  -- 40 zeroes for deletions
+  filenode TEXT NOT NULL,
+-- to handle filelog parentage:
+  p1node TEXT,
+  p1filenode TEXT,
+  p2node TEXT,
+  p2filenode TEXT
+);
+
+CREATE INDEX changedfiles_nodes_idx
+  ON changedfiles(node);
+
+PRAGMA user_version=%d
+"""
+    % _CURRENT_SCHEMA_VERSION
+)
+
+
+def _createdb(path):
+    # print('open db', path)
+    # import traceback
+    # traceback.print_stack()
+    db = sqlite3.connect(encoding.strfromlocal(path))
+    db.text_factory = bytes
+
+    res = db.execute('PRAGMA user_version').fetchone()[0]
+
+    # New database.
+    if res == 0:
+        for statement in _SCHEMA.split(';'):
+            db.execute(statement.strip())
+
+        db.commit()
+
+    elif res == _CURRENT_SCHEMA_VERSION:
+        pass
+
+    else:
+        raise error.Abort(_(b'sqlite database has unrecognized version'))
+
+    db.execute('PRAGMA journal_mode=WAL')
+
+    return db
+
+
+_OUR_ORDER = (
+    pygit2.GIT_SORT_TOPOLOGICAL | pygit2.GIT_SORT_TIME | pygit2.GIT_SORT_REVERSE
+)
+
+_DIFF_FLAGS = 1 << 21  # GIT_DIFF_FORCE_BINARY, which isn't exposed by pygit2
+
+
+def _find_nearest_ancestor_introducing_node(
+    db, gitrepo, file_path, walk_start, filenode
+):
+    """Find the nearest ancestor that introduces a file node.
+
+    Args:
+      db: a handle to our sqlite database.
+      gitrepo: A pygit2.Repository instance.
+      file_path: the path of a file in the repo
+      walk_start: a pygit2.Oid that is a commit where we should start walking
+                  for our nearest ancestor.
+
+    Returns:
+      A hexlified SHA that is the commit ID of the next-nearest parent.
+    """
+    assert isinstance(file_path, str), 'file_path must be str, got %r' % type(
+        file_path
+    )
+    assert isinstance(filenode, str), 'filenode must be str, got %r' % type(
+        filenode
+    )
+    parent_options = {
+        row[0].decode('ascii')
+        for row in db.execute(
+            'SELECT node FROM changedfiles '
+            'WHERE filename = ? AND filenode = ?',
+            (file_path, filenode),
+        )
+    }
+    inner_walker = gitrepo.walk(walk_start, _OUR_ORDER)
+    for w in inner_walker:
+        if w.id.hex in parent_options:
+            return w.id.hex
+    raise error.ProgrammingError(
+        'Unable to find introducing commit for %s node %s from %s',
+        (file_path, filenode, walk_start),
+    )
+
+
+def fill_in_filelog(gitrepo, db, startcommit, path, startfilenode):
+    """Given a starting commit and path, fill in a filelog's parent pointers.
+
+    Args:
+      gitrepo: a pygit2.Repository
+      db: a handle to our sqlite database
+      startcommit: a hexlified node id for the commit to start at
+      path: the path of the file whose parent pointers we should fill in.
+      filenode: the hexlified node id of the file at startcommit
+
+    TODO: make filenode optional
+    """
+    assert isinstance(
+        startcommit, str
+    ), 'startcommit must be str, got %r' % type(startcommit)
+    assert isinstance(
+        startfilenode, str
+    ), 'startfilenode must be str, got %r' % type(startfilenode)
+    visit = collections.deque([(startcommit, startfilenode)])
+    while visit:
+        cnode, filenode = visit.popleft()
+        commit = gitrepo[cnode]
+        parents = []
+        for parent in commit.parents:
+            t = parent.tree
+            for comp in path.split('/'):
+                try:
+                    t = gitrepo[t[comp].id]
+                except KeyError:
+                    break
+            else:
+                introducer = _find_nearest_ancestor_introducing_node(
+                    db, gitrepo, path, parent.id, t.id.hex
+                )
+                parents.append((introducer, t.id.hex))
+        p1node = p1fnode = p2node = p2fnode = gitutil.nullgit
+        for par, parfnode in parents:
+            found = int(
+                db.execute(
+                    'SELECT COUNT(*) FROM changedfiles WHERE '
+                    'node = ? AND filename = ? AND filenode = ? AND '
+                    'p1node NOT NULL',
+                    (par, path, parfnode),
+                ).fetchone()[0]
+            )
+            if found == 0:
+                assert par is not None
+                visit.append((par, parfnode))
+        if parents:
+            p1node, p1fnode = parents[0]
+        if len(parents) == 2:
+            p2node, p2fnode = parents[1]
+        if len(parents) > 2:
+            raise error.ProgrammingError(
+                b"git support can't handle octopus merges"
+            )
+        db.execute(
+            'UPDATE changedfiles SET '
+            'p1node = ?, p1filenode = ?, p2node = ?, p2filenode = ? '
+            'WHERE node = ? AND filename = ? AND filenode = ?',
+            (p1node, p1fnode, p2node, p2fnode, commit.id.hex, path, filenode),
+        )
+    db.commit()
+
+
+def _index_repo(gitrepo, db, progress_factory=lambda *args, **kwargs: None):
+    # Identify all references so we can tell the walker to visit all of them.
+    all_refs = gitrepo.listall_references()
+    possible_heads = set()
+    prog = progress_factory(b'refs')
+    for pos, ref in enumerate(all_refs):
+        if prog is not None:
+            prog.update(pos)
+        if not (
+            ref.startswith('refs/heads/')  # local branch
+            or ref.startswith('refs/tags/')  # tag
+            or ref.startswith('refs/remotes/')  # remote branch
+            or ref.startswith('refs/hg/')  # from this extension
+        ):
+            continue
+        try:
+            start = gitrepo.lookup_reference(ref).peel(pygit2.GIT_OBJ_COMMIT)
+        except ValueError:
+            # No commit to be found, so we don't care for hg's purposes.
+            continue
+        possible_heads.add(start.id)
+    # Optimization: if the list of heads hasn't changed, don't
+    # reindex, the changelog. This doesn't matter on small
+    # repositories, but on even moderately deep histories (eg cpython)
+    # this is a very important performance win.
+    #
+    # TODO: we should figure out how to incrementally index history
+    # (preferably by detecting rewinds!) so that we don't have to do a
+    # full changelog walk every time a new commit is created.
+    cache_heads = {x[0] for x in db.execute('SELECT node FROM possible_heads')}
+    walker = None
+    cur_cache_heads = {h.hex for h in possible_heads}
+    if cur_cache_heads == cache_heads:
+        return
+    for start in possible_heads:
+        if walker is None:
+            walker = gitrepo.walk(start, _OUR_ORDER)
+        else:
+            walker.push(start)
+
+    # Empty out the existing changelog. Even for large-ish histories
+    # we can do the top-level "walk all the commits" dance very
+    # quickly as long as we don't need to figure out the changed files
+    # list.
+    db.execute('DELETE FROM changelog')
+    if prog is not None:
+        prog.complete()
+    prog = progress_factory(b'commits')
+    # This walker is sure to visit all the revisions in history, but
+    # only once.
+    for pos, commit in enumerate(walker):
+        if prog is not None:
+            prog.update(pos)
+        p1 = p2 = nodemod.nullhex
+        if len(commit.parents) > 2:
+            raise error.ProgrammingError(
+                (
+                    b"git support can't handle octopus merges, "
+                    b"found a commit with %d parents :("
+                )
+                % len(commit.parents)
+            )
+        if commit.parents:
+            p1 = commit.parents[0].id.hex
+        if len(commit.parents) == 2:
+            p2 = commit.parents[1].id.hex
+        db.execute(
+            'INSERT INTO changelog (rev, node, p1, p2) VALUES(?, ?, ?, ?)',
+            (pos, commit.id.hex, p1, p2),
+        )
+
+        num_changedfiles = db.execute(
+            "SELECT COUNT(*) from changedfiles WHERE node = ?",
+            (commit.id.hex,),
+        ).fetchone()[0]
+        if not num_changedfiles:
+            files = {}
+            # I *think* we only need to check p1 for changed files
+            # (and therefore linkrevs), because any node that would
+            # actually have this commit as a linkrev would be
+            # completely new in this rev.
+            p1 = commit.parents[0].id.hex if commit.parents else None
+            if p1 is not None:
+                patchgen = gitrepo.diff(p1, commit.id.hex, flags=_DIFF_FLAGS)
+            else:
+                patchgen = commit.tree.diff_to_tree(
+                    swap=True, flags=_DIFF_FLAGS
+                )
+            new_files = (p.delta.new_file for p in patchgen)
+            files = {
+                nf.path: nf.id.hex
+                for nf in new_files
+                if nf.id.raw != nodemod.nullid
+            }
+            for p, n in files.items():
+                # We intentionally set NULLs for any file parentage
+                # information so it'll get demand-computed later. We
+                # used to do it right here, and it was _very_ slow.
+                db.execute(
+                    'INSERT INTO changedfiles ('
+                    'node, filename, filenode, p1node, p1filenode, p2node, '
+                    'p2filenode) VALUES(?, ?, ?, ?, ?, ?, ?)',
+                    (commit.id.hex, p, n, None, None, None, None),
+                )
+    db.execute('DELETE FROM heads')
+    db.execute('DELETE FROM possible_heads')
+    for hid in possible_heads:
+        h = hid.hex
+        db.execute('INSERT INTO possible_heads (node) VALUES(?)', (h,))
+        haschild = db.execute(
+            'SELECT COUNT(*) FROM changelog WHERE p1 = ? OR p2 = ?', (h, h)
+        ).fetchone()[0]
+        if not haschild:
+            db.execute('INSERT INTO heads (node) VALUES(?)', (h,))
+
+    db.commit()
+    if prog is not None:
+        prog.complete()
+
+
+def get_index(gitrepo, progress_factory=lambda *args, **kwargs: None):
+    cachepath = os.path.join(
+        pycompat.fsencode(gitrepo.path), b'..', b'.hg', b'cache'
+    )
+    if not os.path.exists(cachepath):
+        os.makedirs(cachepath)
+    dbpath = os.path.join(cachepath, b'git-commits.sqlite')
+    db = _createdb(dbpath)
+    # TODO check against gitrepo heads before doing a full index
+    # TODO thread a ui.progress call into this layer
+    _index_repo(gitrepo, db, progress_factory)
+    return db

hgext/git/manifest.py

@@ -0,0 +1,293 b''
+from __future__ import absolute_import
+
+import pygit2
+
+from mercurial import (
+    match as matchmod,
+    pathutil,
+    pycompat,
+    util,
+)
+from mercurial.interfaces import (
+    repository,
+    util as interfaceutil,
+)
+from . import gitutil
+
+
[e-mail](repository.imanifestdict)
+class gittreemanifest(object):
+    """Expose git trees (and optionally a builder's overlay) as a manifestdict.
+
+    Very similar to mercurial.manifest.treemanifest.
+    """
+
+    def __init__(self, git_repo, root_tree, pending_changes):
+        """Initializer.
+
+        Args:
+          git_repo: The git_repo we're walking (required to look up child
+              trees).
+          root_tree: The root Git tree object for this manifest.
+          pending_changes: A dict in which pending changes will be
+              tracked. The enclosing memgittreemanifestctx will use this to
+              construct any required Tree objects in Git during it's
+              `write()` method.
+        """
+        self._git_repo = git_repo
+        self._tree = root_tree
+        if pending_changes is None:
+            pending_changes = {}
+        # dict of path: Optional[Tuple(node, flags)]
+        self._pending_changes = pending_changes
+
+    def _resolve_entry(self, path):
+        """Given a path, load its node and flags, or raise KeyError if missing.
+
+        This takes into account any pending writes in the builder.
+        """
+        upath = pycompat.fsdecode(path)
+        ent = None
+        if path in self._pending_changes:
+            val = self._pending_changes[path]
+            if val is None:
+                raise KeyError
+            return val
+        t = self._tree
+        comps = upath.split('/')
+        for comp in comps[:-1]:
+            te = self._tree[comp]
+            t = self._git_repo[te.id]
+        ent = t[comps[-1]]
+        if ent.filemode == pygit2.GIT_FILEMODE_BLOB:
+            flags = b''
+        elif ent.filemode == pygit2.GIT_FILEMODE_BLOB_EXECUTABLE:
+            flags = b'x'
+        elif ent.filemode == pygit2.GIT_FILEMODE_LINK:
+            flags = b'l'
+        else:
+            raise ValueError('unsupported mode %s' % oct(ent.filemode))
+        return ent.id.raw, flags
+
+    def __getitem__(self, path):
+        return self._resolve_entry(path)[0]
+
+    def find(self, path):
+        return self._resolve_entry(path)
+
+    def __len__(self):
+        return len(list(self.walk(matchmod.always())))
+
+    def __nonzero__(self):
+        try:
+            next(iter(self))
+            return True
+        except StopIteration:
+            return False
+
+    __bool__ = __nonzero__
+
+    def __contains__(self, path):
+        try:
+            self._resolve_entry(path)
+            return True
+        except KeyError:
+            return False
+
+    def iterkeys(self):
+        return self.walk(matchmod.always())
+
+    def keys(self):
+        return list(self.iterkeys())
+
+    def __iter__(self):
+        return self.iterkeys()
+
+    def __setitem__(self, path, node):
+        self._pending_changes[path] = node, self.flags(path)
+
+    def __delitem__(self, path):
+        # TODO: should probably KeyError for already-deleted  files?
+        self._pending_changes[path] = None
+
+    def filesnotin(self, other, match=None):
+        if match is not None:
+            match = matchmod.badmatch(match, lambda path, msg: None)
+            sm2 = set(other.walk(match))
+            return {f for f in self.walk(match) if f not in sm2}
+        return {f for f in self if f not in other}
+
+    @util.propertycache
+    def _dirs(self):
+        return pathutil.dirs(self)
+
+    def hasdir(self, dir):
+        return dir in self._dirs
+
+    def diff(self, other, match=None, clean=False):
+        # TODO
+        assert False
+
+    def setflag(self, path, flag):
+        node, unused_flag = self._resolve_entry(path)
+        self._pending_changes[path] = node, flag
+
+    def get(self, path, default=None):
+        try:
+            return self._resolve_entry(path)[0]
+        except KeyError:
+            return default
+
+    def flags(self, path):
+        try:
+            return self._resolve_entry(path)[1]
+        except KeyError:
+            return b''
+
+    def copy(self):
+        pass
+
+    def items(self):
+        for f in self:
+            # TODO: build a proper iterator version of this
+            yield self[f]
+
+    def iteritems(self):
+        return self.items()
+
+    def iterentries(self):
+        for f in self:
+            # TODO: build a proper iterator version of this
+            yield self._resolve_entry(f)
+
+    def text(self):
+        assert False  # TODO can this method move out of the manifest iface?
+
+    def _walkonetree(self, tree, match, subdir):
+        for te in tree:
+            # TODO: can we prune dir walks with the matcher?
+            realname = subdir + pycompat.fsencode(te.name)
+            if te.type == r'tree':
+                for inner in self._walkonetree(
+                    self._git_repo[te.id], match, realname + b'/'
+                ):
+                    yield inner
+            if not match(realname):
+                continue
+            yield pycompat.fsencode(realname)
+
+    def walk(self, match):
+        # TODO: this is a very lazy way to merge in the pending
+        # changes. There is absolutely room for optimization here by
+        # being clever about walking over the sets...
+        baseline = set(self._walkonetree(self._tree, match, b''))
+        deleted = {p for p, v in self._pending_changes.items() if v is None}
+        pend = {p for p in self._pending_changes if match(p)}
+        return iter(sorted((baseline | pend) - deleted))
+
+
[e-mail](repository.imanifestrevisionstored)
+class gittreemanifestctx(object):
+    def __init__(self, repo, gittree):
+        self._repo = repo
+        self._tree = gittree
+
+    def read(self):
+        return gittreemanifest(self._repo, self._tree, None)
+
+    def copy(self):
+        # NB: it's important that we return a memgittreemanifestctx
+        # because the caller expects a mutable manifest.
+        return memgittreemanifestctx(self._repo, self._tree)
+
+    def find(self, path):
+        self.read()[path]
+
+
[e-mail](repository.imanifestrevisionwritable)
+class memgittreemanifestctx(object):
+    def __init__(self, repo, tree):
+        self._repo = repo
+        self._tree = tree
+        # dict of path: Optional[Tuple(node, flags)]
+        self._pending_changes = {}
+
+    def read(self):
+        return gittreemanifest(self._repo, self._tree, self._pending_changes)
+
+    def copy(self):
+        # TODO: if we have a builder in play, what should happen here?
+        # Maybe we can shuffle copy() into the immutable interface.
+        return memgittreemanifestctx(self._repo, self._tree)
+
+    def write(self, transaction, link, p1, p2, added, removed, match=None):
+        # We're not (for now, anyway) going to audit filenames, so we
+        # can ignore added and removed.
+
+        # TODO what does this match argument get used for? hopefully
+        # just narrow?
+        assert not match or isinstance(match, matchmod.alwaysmatcher)
+
+        touched_dirs = pathutil.dirs(self._pending_changes)
+        trees = {
+            b'': self._tree,
+        }
+        # path: treebuilder
+        builders = {
+            b'': self._repo.TreeBuilder(self._tree),
+        }
+        # get a TreeBuilder for every tree in the touched_dirs set
+        for d in sorted(touched_dirs, key=lambda x: (len(x), x)):
+            if d == b'':
+                # loaded root tree above
+                continue
+            comps = d.split(b'/')
+            full = b''
+            for part in comps:
+                parent = trees[full]
+                try:
+                    new = self._repo[parent[pycompat.fsdecode(part)]]
+                except KeyError:
+                    # new directory
+                    new = None
+                full += b'/' + part
+                if new is not None:
+                    # existing directory
+                    trees[full] = new
+                    builders[full] = self._repo.TreeBuilder(new)
+                else:
+                    # new directory, use an empty dict to easily
+                    # generate KeyError as any nested new dirs get
+                    # created.
+                    trees[full] = {}
+                    builders[full] = self._repo.TreeBuilder()
+        for f, info in self._pending_changes.items():
+            if b'/' not in f:
+                dirname = b''
+                basename = f
+            else:
+                dirname, basename = f.rsplit(b'/', 1)
+                dirname = b'/' + dirname
+            if info is None:
+                builders[dirname].remove(pycompat.fsdecode(basename))
+            else:
+                n, fl = info
+                mode = {
+                    b'': pygit2.GIT_FILEMODE_BLOB,
+                    b'x': pygit2.GIT_FILEMODE_BLOB_EXECUTABLE,
+                    b'l': pygit2.GIT_FILEMODE_LINK,
+                }[fl]
+                builders[dirname].insert(
+                    pycompat.fsdecode(basename), gitutil.togitnode(n), mode
+                )
+        # This visits the buffered TreeBuilders in deepest-first
+        # order, bubbling up the edits.
+        for b in sorted(builders, key=len, reverse=True):
+            if b == b'':
+                break
+            cb = builders[b]
+            dn, bn = b.rsplit(b'/', 1)
+            builders[dn].insert(
+                pycompat.fsdecode(bn), cb.write(), pygit2.GIT_FILEMODE_TREE
+            )
+        return builders[b''].write().raw

tests/test-git-interop.t

@@ -0,0 +1,223 b''
+This test requires pygit2:
+  > $PYTHON -c 'import pygit2' || exit 80
+
+Setup:
+  > GIT_AUTHOR_NAME='test'; export GIT_AUTHOR_NAME
+  > GIT_AUTHOR_EMAIL='[e-mail]'; export GIT_AUTHOR_EMAIL
+  > GIT_AUTHOR_DATE="2007-01-01 00:00:00 +0000"; export GIT_AUTHOR_DATE
+  > GIT_COMMITTER_NAME="$GIT_AUTHOR_NAME"; export GIT_COMMITTER_NAME
+  > GIT_COMMITTER_EMAIL="$GIT_AUTHOR_EMAIL"; export GIT_COMMITTER_EMAIL
+  > GIT_COMMITTER_DATE="$GIT_AUTHOR_DATE"; export GIT_COMMITTER_DATE
+
+  > count=10
+  > gitcommit() {
+  >    GIT_AUTHOR_DATE="2007-01-01 00:00:$count +0000";
+  >    GIT_COMMITTER_DATE="$GIT_AUTHOR_DATE"
+  >    git commit "$@" >/dev/null 2>/dev/null || echo "git commit error"
+  >    count=`expr $count + 1`
+  >  }
+
+  > echo "[extensions]" >> $HGRCPATH
+  > echo "git=" >> $HGRCPATH
+
+Make a new repo with git:
+  $ mkdir foo
+  $ cd foo
+  $ git init
+  Initialized empty Git repository in $TESTTMP/foo/.git/
+Ignore the .hg directory within git:
+  $ echo .hg >> .git/info/exclude
+  $ echo alpha > alpha
+  $ git add alpha
+  $ gitcommit -am 'Add alpha'
+  $ echo beta > beta
+  $ git add beta
+  $ gitcommit -am 'Add beta'
+  $ echo gamma > gamma
+  $ git status
+  On branch master
+  Untracked files:
+    (use "git add <file>..." to include in what will be committed)
+  	gamma
+  
+  nothing added to commit but untracked files present (use "git add" to track)
+
+Without creating the .hg, hg status fails:
+  $ hg status
+  abort: no repository found in '$TESTTMP/foo' (.hg not found)!
+  [255]
+But if you run hg init --git, it works:
+  $ hg init --git
+  $ hg id --traceback
+  3d9be8deba43 tip master
+  $ hg status
+  ? gamma
+Log works too:
+  $ hg log
+  changeset:   1:3d9be8deba43
+  bookmark:    master
+  tag:         tip
+  user:        test <[e-mail]>
+  date:        Mon Jan 01 00:00:11 2007 +0000
+  summary:     Add beta
+  
+  changeset:   0:c5864c9d16fb
+  user:        test <[e-mail]>
+  date:        Mon Jan 01 00:00:10 2007 +0000
+  summary:     Add alpha
+  
+
+
+and bookmarks:
+  $ hg bookmarks
+   * master                    1:3d9be8deba43
+
+diff even works transparently in both systems:
+  $ echo blah >> alpha
+  $ git diff
+  diff --git a/alpha b/alpha
+  index 4a58007..faed1b7 100644
+  --- a/alpha
+  +++ b/alpha
+  @@ -1* +1,2 @@ (glob)
+   alpha
+  +blah
+  $ hg diff --git
+  diff --git a/alpha b/alpha
+  --- a/alpha
+  +++ b/alpha
+  @@ -1,1 +1,2 @@
+   alpha
+  +blah
+
+Remove a file, it shows as such:
+  $ rm alpha
+  $ hg status
+  ! alpha
+  ? gamma
+
+Revert works:
+  $ hg revert alpha --traceback
+  $ hg status
+  ? gamma
+  $ git status
+  On branch master
+  Untracked files:
+    (use "git add <file>..." to include in what will be committed)
+  	gamma
+  
+  nothing added to commit but untracked files present (use "git add" to track)
+
+Add shows sanely in both:
+  $ hg add gamma
+  $ hg status
+  A gamma
+  $ hg files
+  alpha
+  beta
+  gamma
+  $ git ls-files
+  alpha
+  beta
+  gamma
+  $ git status
+  On branch master
+  Changes to be committed:
+    (use "git restore --staged <file>..." to unstage)
+  	new file:   gamma
+  
+
+forget does what it should as well:
+  $ hg forget gamma
+  $ hg status
+  ? gamma
+  $ git status
+  On branch master
+  Untracked files:
+    (use "git add <file>..." to include in what will be committed)
+  	gamma
+  
+  nothing added to commit but untracked files present (use "git add" to track)
+
+clean up untracked file
+  $ rm gamma
+
+hg log FILE
+
+  $ echo a >> alpha
+  $ hg ci -m 'more alpha' --traceback --date '1583522787 18000'
+  $ echo b >> beta
+  $ hg ci -m 'more beta'
+  $ echo a >> alpha
+  $ hg ci -m 'even more alpha'
+  $ hg log -G alpha
+  @  changeset:   4:6626247b7dc8
+  :  bookmark:    master
+  :  tag:         tip
+  :  user:        test <test>
+  :  date:        Thu Jan 01 00:00:00 1970 +0000
+  :  summary:     even more alpha
+  :
+  o  changeset:   2:a1983dd7fb19
+  :  user:        test <test>
+  :  date:        Fri Mar 06 14:26:27 2020 -0500
+  :  summary:     more alpha
+  :
+  o  changeset:   0:c5864c9d16fb
+     user:        test <[e-mail]>
+     date:        Mon Jan 01 00:00:10 2007 +0000
+     summary:     Add alpha
+  
+  $ hg log -G beta
+  o  changeset:   3:d8ee22687733
+  :  user:        test <test>
+  :  date:        Thu Jan 01 00:00:00 1970 +0000
+  :  summary:     more beta
+  :
+  o  changeset:   1:3d9be8deba43
+  |  user:        test <[e-mail]>
+  ~  date:        Mon Jan 01 00:00:11 2007 +0000
+     summary:     Add beta
+  
+
+node|shortest works correctly
+  $ hg log -r tip --template "{node|shortest}\n"
+  6626
+
+hg annotate
+
+  $ hg annotate alpha
+  0: alpha
+  2: a
+  4: a
+  $ hg annotate beta
+  1: beta
+  3: b
+
+
+Files in subdirectories. TODO: case-folding support, make this `A`
+instead of `a`.
+
+  $ mkdir a
+  $ echo "This is file mu." > a/mu
+  $ hg ci -A -m 'Introduce file a/mu'
+  adding a/mu
+
+Both hg and git agree a/mu is part of the repo
+
+  $ git ls-files
+  a/mu
+  alpha
+  beta
+  $ hg files
+  a/mu
+  alpha
+  beta
+
+hg and git status both clean
+
+  $ git status
+  On branch master
+  nothing to commit, working tree clean
+  $ hg status
+

setup.py

@@ -1,1739 +1,1740 b''
 #
 # This is the mercurial setup script.
 #
 # 'python setup.py install', or
 # 'python setup.py --help' for more options
 
 import os
 
 # Mercurial will never work on Python 3 before 3.5 due to a lack
 # of % formatting on bytestrings, and can't work on 3.6.0 or 3.6.1
 # due to a bug in % formatting in bytestrings.
 # We cannot support Python 3.5.0, 3.5.1, 3.5.2 because of bug in
 # codecs.escape_encode() where it raises SystemError on empty bytestring
 # bug link: https://bugs.python.org/issue25270
 supportedpy = ','.join(
     [
         '>=2.7',
         '!=3.0.*',
         '!=3.1.*',
         '!=3.2.*',
         '!=3.3.*',
         '!=3.4.*',
         '!=3.5.0',
         '!=3.5.1',
         '!=3.5.2',
         '!=3.6.0',
         '!=3.6.1',
     ]
 )
 
 import sys, platform
 import sysconfig
 
 if sys.version_info[0] >= 3:
     printf = eval('print')
     libdir_escape = 'unicode_escape'
 
     def sysstr(s):
         return s.decode('latin-1')
 
 
 else:
     libdir_escape = 'string_escape'
 
     def printf(*args, **kwargs):
         f = kwargs.get('file', sys.stdout)
         end = kwargs.get('end', '\n')
         f.write(b' '.join(args) + end)
 
     def sysstr(s):
         return s
 
 
 # Attempt to guide users to a modern pip - this means that 2.6 users
 # should have a chance of getting a 4.2 release, and when we ratchet
 # the version requirement forward again hopefully everyone will get
 # something that works for them.
 if sys.version_info < (2, 7, 0, 'final'):
     pip_message = (
         'This may be due to an out of date pip. '
         'Make sure you have pip >= 9.0.1.'
     )
     try:
         import pip
 
         pip_version = tuple([int(x) for x in pip.__version__.split('.')[:3]])
         if pip_version < (9, 0, 1):
             pip_message = (
                 'Your pip version is out of date, please install '
                 'pip >= 9.0.1. pip {} detected.'.format(pip.__version__)
             )
         else:
             # pip is new enough - it must be something else
             pip_message = ''
     except Exception:
         pass
     error = """
 Mercurial does not support Python older than 2.7.
 Python {py} detected.
 {pip}
 """.format(
         py=sys.version_info, pip=pip_message
     )
     printf(error, file=sys.stderr)
     sys.exit(1)
 
 if sys.version_info[0] >= 3:
     DYLIB_SUFFIX = sysconfig.get_config_vars()['EXT_SUFFIX']
 else:
     # deprecated in Python 3
     DYLIB_SUFFIX = sysconfig.get_config_vars()['SO']
 
 # Solaris Python packaging brain damage
 try:
     import hashlib
 
     sha = hashlib.sha1()
 except ImportError:
     try:
         import sha
 
         sha.sha  # silence unused import warning
     except ImportError:
         raise SystemExit(
             "Couldn't import standard hashlib (incomplete Python install)."
         )
 
 try:
     import zlib
 
     zlib.compressobj  # silence unused import warning
 except ImportError:
     raise SystemExit(
         "Couldn't import standard zlib (incomplete Python install)."
     )
 
 # The base IronPython distribution (as of 2.7.1) doesn't support bz2
 isironpython = False
 try:
     isironpython = (
         platform.python_implementation().lower().find("ironpython") != -1
     )
 except AttributeError:
     pass
 
 if isironpython:
     sys.stderr.write("warning: IronPython detected (no bz2 support)\n")
 else:
     try:
         import bz2
 
         bz2.BZ2Compressor  # silence unused import warning
     except ImportError:
         raise SystemExit(
             "Couldn't import standard bz2 (incomplete Python install)."
         )
 
 ispypy = "PyPy" in sys.version
 
 hgrustext = os.environ.get('HGWITHRUSTEXT')
 # TODO record it for proper rebuild upon changes
 # (see mercurial/__modulepolicy__.py)
 if hgrustext != 'cpython' and hgrustext is not None:
     hgrustext = 'direct-ffi'
 
 import ctypes
 import errno
 import stat, subprocess, time
 import re
 import shutil
 import tempfile
 from distutils import log
 
 # We have issues with setuptools on some platforms and builders. Until
 # those are resolved, setuptools is opt-in except for platforms where
 # we don't have issues.
 issetuptools = os.name == 'nt' or 'FORCE_SETUPTOOLS' in os.environ
 if issetuptools:
     from setuptools import setup
 else:
     from distutils.core import setup
 from distutils.ccompiler import new_compiler
 from distutils.core import Command, Extension
 from distutils.dist import Distribution
 from distutils.command.build import build
 from distutils.command.build_ext import build_ext
 from distutils.command.build_py import build_py
 from distutils.command.build_scripts import build_scripts
 from distutils.command.install import install
 from distutils.command.install_lib import install_lib
 from distutils.command.install_scripts import install_scripts
 from distutils.spawn import spawn, find_executable
 from distutils import file_util
 from distutils.errors import (
     CCompilerError,
     DistutilsError,
     DistutilsExecError,
 )
 from distutils.sysconfig import get_python_inc, get_config_var
 from distutils.version import StrictVersion
 
 # Explain to distutils.StrictVersion how our release candidates are versionned
 StrictVersion.version_re = re.compile(r'^(\d+)\.(\d+)(\.(\d+))?-?(rc(\d+))?$')
 
 
 def write_if_changed(path, content):
     """Write content to a file iff the content hasn't changed."""
     if os.path.exists(path):
         with open(path, 'rb') as fh:
             current = fh.read()
     else:
         current = b''
 
     if current != content:
         with open(path, 'wb') as fh:
             fh.write(content)
 
 
 scripts = ['hg']
 if os.name == 'nt':
     # We remove hg.bat if we are able to build hg.exe.
     scripts.append('contrib/win32/hg.bat')
 
 
 def cancompile(cc, code):
     tmpdir = tempfile.mkdtemp(prefix='hg-install-')
     devnull = oldstderr = None
     try:
         fname = os.path.join(tmpdir, 'testcomp.c')
         f = open(fname, 'w')
         f.write(code)
         f.close()
         # Redirect stderr to /dev/null to hide any error messages
         # from the compiler.
         # This will have to be changed if we ever have to check
         # for a function on Windows.
         devnull = open('/dev/null', 'w')
         oldstderr = os.dup(sys.stderr.fileno())
         os.dup2(devnull.fileno(), sys.stderr.fileno())
         objects = cc.compile([fname], output_dir=tmpdir)
         cc.link_executable(objects, os.path.join(tmpdir, "a.out"))
         return True
     except Exception:
         return False
     finally:
         if oldstderr is not None:
             os.dup2(oldstderr, sys.stderr.fileno())
         if devnull is not None:
             devnull.close()
         shutil.rmtree(tmpdir)
 
 
 # simplified version of distutils.ccompiler.CCompiler.has_function
 # that actually removes its temporary files.
 def hasfunction(cc, funcname):
     code = 'int main(void) { %s(); }\n' % funcname
     return cancompile(cc, code)
 
 
 def hasheader(cc, headername):
     code = '#include <%s>\nint main(void) { return 0; }\n' % headername
     return cancompile(cc, code)
 
 
 # py2exe needs to be installed to work
 try:
     import py2exe
 
     py2exe.Distribution  # silence unused import warning
     py2exeloaded = True
     # import py2exe's patched Distribution class
     from distutils.core import Distribution
 except ImportError:
     py2exeloaded = False
 
 
 def runcmd(cmd, env, cwd=None):
     p = subprocess.Popen(
         cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, env=env, cwd=cwd
     )
     out, err = p.communicate()
     return p.returncode, out, err
 
 
 class hgcommand(object):
     def __init__(self, cmd, env):
         self.cmd = cmd
         self.env = env
 
     def run(self, args):
         cmd = self.cmd + args
         returncode, out, err = runcmd(cmd, self.env)
         err = filterhgerr(err)
         if err or returncode != 0:
             printf("stderr from '%s':" % (' '.join(cmd)), file=sys.stderr)
             printf(err, file=sys.stderr)
             return ''
         return out
 
 
 def filterhgerr(err):
     # If root is executing setup.py, but the repository is owned by
     # another user (as in "sudo python setup.py install") we will get
     # trust warnings since the .hg/hgrc file is untrusted. That is
     # fine, we don't want to load it anyway.  Python may warn about
     # a missing __init__.py in mercurial/locale, we also ignore that.
     err = [
         e
         for e in err.splitlines()
         if (
             not e.startswith(b'not trusting file')
             and not e.startswith(b'warning: Not importing')
             and not e.startswith(b'obsolete feature not enabled')
             and not e.startswith(b'*** failed to import extension')
             and not e.startswith(b'devel-warn:')
             and not (
                 e.startswith(b'(third party extension')
                 and e.endswith(b'or newer of Mercurial; disabling)')
             )
         )
     ]
     return b'\n'.join(b'  ' + e for e in err)
 
 
 def findhg():
     """Try to figure out how we should invoke hg for examining the local
     repository contents.
 
     Returns an hgcommand object."""
     # By default, prefer the "hg" command in the user's path.  This was
     # presumably the hg command that the user used to create this repository.
     #
     # This repository may require extensions or other settings that would not
     # be enabled by running the hg script directly from this local repository.
     hgenv = os.environ.copy()
     # Use HGPLAIN to disable hgrc settings that would change output formatting,
     # and disable localization for the same reasons.
     hgenv['HGPLAIN'] = '1'
     hgenv['LANGUAGE'] = 'C'
     hgcmd = ['hg']
     # Run a simple "hg log" command just to see if using hg from the user's
     # path works and can successfully interact with this repository.  Windows
     # gives precedence to hg.exe in the current directory, so fall back to the
     # python invocation of local hg, where pythonXY.dll can always be found.
     check_cmd = ['log', '-r.', '-Ttest']
     if os.name != 'nt' or not os.path.exists("hg.exe"):
         try:
             retcode, out, err = runcmd(hgcmd + check_cmd, hgenv)
         except EnvironmentError:
             retcode = -1
         if retcode == 0 and not filterhgerr(err):
             return hgcommand(hgcmd, hgenv)
 
     # Fall back to trying the local hg installation.
     hgenv = localhgenv()
     hgcmd = [sys.executable, 'hg']
     try:
         retcode, out, err = runcmd(hgcmd + check_cmd, hgenv)
     except EnvironmentError:
         retcode = -1
     if retcode == 0 and not filterhgerr(err):
         return hgcommand(hgcmd, hgenv)
 
     raise SystemExit(
         'Unable to find a working hg binary to extract the '
         'version from the repository tags'
     )
 
 
 def localhgenv():
     """Get an environment dictionary to use for invoking or importing
     mercurial from the local repository."""
     # Execute hg out of this directory with a custom environment which takes
     # care to not use any hgrc files and do no localization.
     env = {
         'HGMODULEPOLICY': 'py',
         'HGRCPATH': '',
         'LANGUAGE': 'C',
         'PATH': '',
     }  # make pypi modules that use os.environ['PATH'] happy
     if 'LD_LIBRARY_PATH' in os.environ:
         env['LD_LIBRARY_PATH'] = os.environ['LD_LIBRARY_PATH']
     if 'SystemRoot' in os.environ:
         # SystemRoot is required by Windows to load various DLLs.  See:
         # https://bugs.python.org/issue13524#msg148850
         env['SystemRoot'] = os.environ['SystemRoot']
     return env
 
 
 version = ''
 
 if os.path.isdir('.hg'):
     hg = findhg()
     cmd = ['log', '-r', '.', '--template', '{tags}\n']
     numerictags = [t for t in sysstr(hg.run(cmd)).split() if t[0:1].isdigit()]
     hgid = sysstr(hg.run(['id', '-i'])).strip()
     if not hgid:
         # Bail out if hg is having problems interacting with this repository,
         # rather than falling through and producing a bogus version number.
         # Continuing with an invalid version number will break extensions
         # that define minimumhgversion.
         raise SystemExit('Unable to determine hg version from local repository')
     if numerictags:  # tag(s) found
         version = numerictags[-1]
         if hgid.endswith('+'):  # propagate the dirty status to the tag
             version += '+'
     else:  # no tag found
         ltagcmd = ['parents', '--template', '{latesttag}']
         ltag = sysstr(hg.run(ltagcmd))
         changessincecmd = ['log', '-T', 'x\n', '-r', "only(.,'%s')" % ltag]
         changessince = len(hg.run(changessincecmd).splitlines())
         version = '%s+%s-%s' % (ltag, changessince, hgid)
     if version.endswith('+'):
         version += time.strftime('%Y%m%d')
 elif os.path.exists('.hg_archival.txt'):
     kw = dict(
         [[t.strip() for t in l.split(':', 1)] for l in open('.hg_archival.txt')]
     )
     if 'tag' in kw:
         version = kw['tag']
     elif 'latesttag' in kw:
         if 'changessincelatesttag' in kw:
             version = '%(latesttag)s+%(changessincelatesttag)s-%(node).12s' % kw
         else:
             version = '%(latesttag)s+%(latesttagdistance)s-%(node).12s' % kw
     else:
         version = kw.get('node', '')[:12]
 
 if version:
     versionb = version
     if not isinstance(versionb, bytes):
         versionb = versionb.encode('ascii')
 
     write_if_changed(
         'mercurial/__version__.py',
         b''.join(
             [
                 b'# this file is autogenerated by setup.py\n'
                 b'version = b"%s"\n' % versionb,
             ]
         ),
     )
 
 try:
     oldpolicy = os.environ.get('HGMODULEPOLICY', None)
     os.environ['HGMODULEPOLICY'] = 'py'
     from mercurial import __version__
 
     version = __version__.version
 except ImportError:
     version = b'unknown'
 finally:
     if oldpolicy is None:
         del os.environ['HGMODULEPOLICY']
     else:
         os.environ['HGMODULEPOLICY'] = oldpolicy
 
 
 class hgbuild(build):
     # Insert hgbuildmo first so that files in mercurial/locale/ are found
     # when build_py is run next.
     sub_commands = [('build_mo', None)] + build.sub_commands
 
 
 class hgbuildmo(build):
 
     description = "build translations (.mo files)"
 
     def run(self):
         if not find_executable('msgfmt'):
             self.warn(
                 "could not find msgfmt executable, no translations "
                 "will be built"
             )
             return
 
         podir = 'i18n'
         if not os.path.isdir(podir):
             self.warn("could not find %s/ directory" % podir)
             return
 
         join = os.path.join
         for po in os.listdir(podir):
             if not po.endswith('.po'):
                 continue
             pofile = join(podir, po)
             modir = join('locale', po[:-3], 'LC_MESSAGES')
             mofile = join(modir, 'hg.mo')
             mobuildfile = join('mercurial', mofile)
             cmd = ['msgfmt', '-v', '-o', mobuildfile, pofile]
             if sys.platform != 'sunos5':
                 # msgfmt on Solaris does not know about -c
                 cmd.append('-c')
             self.mkpath(join('mercurial', modir))
             self.make_file([pofile], mobuildfile, spawn, (cmd,))
 
 
 class hgdist(Distribution):
     pure = False
     rust = hgrustext is not None
     cffi = ispypy
 
     global_options = Distribution.global_options + [
         ('pure', None, "use pure (slow) Python code instead of C extensions"),
         ('rust', None, "use Rust extensions additionally to C extensions"),
     ]
 
     def has_ext_modules(self):
         # self.ext_modules is emptied in hgbuildpy.finalize_options which is
         # too late for some cases
         return not self.pure and Distribution.has_ext_modules(self)
 
 
 # This is ugly as a one-liner. So use a variable.
 buildextnegops = dict(getattr(build_ext, 'negative_options', {}))
 buildextnegops['no-zstd'] = 'zstd'
 buildextnegops['no-rust'] = 'rust'
 
 
 class hgbuildext(build_ext):
     user_options = build_ext.user_options + [
         ('zstd', None, 'compile zstd bindings [default]'),
         ('no-zstd', None, 'do not compile zstd bindings'),
         (
             'rust',
             None,
             'compile Rust extensions if they are in use '
             '(requires Cargo) [default]',
         ),
         ('no-rust', None, 'do not compile Rust extensions'),
     ]
 
     boolean_options = build_ext.boolean_options + ['zstd', 'rust']
     negative_opt = buildextnegops
 
     def initialize_options(self):
         self.zstd = True
         self.rust = True
 
         return build_ext.initialize_options(self)
 
     def finalize_options(self):
         # Unless overridden by the end user, build extensions in parallel.
         # Only influences behavior on Python 3.5+.
         if getattr(self, 'parallel', None) is None:
             self.parallel = True
 
         return build_ext.finalize_options(self)
 
     def build_extensions(self):
         ruststandalones = [
             e for e in self.extensions if isinstance(e, RustStandaloneExtension)
         ]
         self.extensions = [
             e for e in self.extensions if e not in ruststandalones
         ]
         # Filter out zstd if disabled via argument.
         if not self.zstd:
             self.extensions = [
                 e for e in self.extensions if e.name != 'mercurial.zstd'
             ]
 
         # Build Rust standalon extensions if it'll be used
         # and its build is not explictely disabled (for external build
         # as Linux distributions would do)
         if self.distribution.rust and self.rust and hgrustext != 'direct-ffi':
             for rustext in ruststandalones:
                 rustext.build('' if self.inplace else self.build_lib)
 
         return build_ext.build_extensions(self)
 
     def build_extension(self, ext):
         if (
             self.distribution.rust
             and self.rust
             and isinstance(ext, RustExtension)
         ):
             ext.rustbuild()
         try:
             build_ext.build_extension(self, ext)
         except CCompilerError:
             if not getattr(ext, 'optional', False):
                 raise
             log.warn(
                 "Failed to build optional extension '%s' (skipping)", ext.name
             )
 
 
 class hgbuildscripts(build_scripts):
     def run(self):
         if os.name != 'nt' or self.distribution.pure:
             return build_scripts.run(self)
 
         exebuilt = False
         try:
             self.run_command('build_hgexe')
             exebuilt = True
         except (DistutilsError, CCompilerError):
             log.warn('failed to build optional hg.exe')
 
         if exebuilt:
             # Copying hg.exe to the scripts build directory ensures it is
             # installed by the install_scripts command.
             hgexecommand = self.get_finalized_command('build_hgexe')
             dest = os.path.join(self.build_dir, 'hg.exe')
             self.mkpath(self.build_dir)
             self.copy_file(hgexecommand.hgexepath, dest)
 
             # Remove hg.bat because it is redundant with hg.exe.
             self.scripts.remove('contrib/win32/hg.bat')
 
         return build_scripts.run(self)
 
 
 class hgbuildpy(build_py):
     def finalize_options(self):
         build_py.finalize_options(self)
 
         if self.distribution.pure:
             self.distribution.ext_modules = []
         elif self.distribution.cffi:
             from mercurial.cffi import (
                 bdiffbuild,
                 mpatchbuild,
             )
 
             exts = [
                 mpatchbuild.ffi.distutils_extension(),
                 bdiffbuild.ffi.distutils_extension(),
             ]
             # cffi modules go here
             if sys.platform == 'darwin':
                 from mercurial.cffi import osutilbuild
 
                 exts.append(osutilbuild.ffi.distutils_extension())
             self.distribution.ext_modules = exts
         else:
             h = os.path.join(get_python_inc(), 'Python.h')
             if not os.path.exists(h):
                 raise SystemExit(
                     'Python headers are required to build '
                     'Mercurial but weren\'t found in %s' % h
                 )
 
     def run(self):
         basepath = os.path.join(self.build_lib, 'mercurial')
         self.mkpath(basepath)
 
         rust = self.distribution.rust
         if self.distribution.pure:
             modulepolicy = 'py'
         elif self.build_lib == '.':
             # in-place build should run without rebuilding and Rust extensions
             modulepolicy = 'rust+c-allow' if rust else 'allow'
         else:
             modulepolicy = 'rust+c' if rust else 'c'
 
         content = b''.join(
             [
                 b'# this file is autogenerated by setup.py\n',
                 b'modulepolicy = b"%s"\n' % modulepolicy.encode('ascii'),
             ]
         )
         write_if_changed(os.path.join(basepath, '__modulepolicy__.py'), content)
 
         build_py.run(self)
 
 
 class buildhgextindex(Command):
     description = 'generate prebuilt index of hgext (for frozen package)'
     user_options = []
     _indexfilename = 'hgext/__index__.py'
 
     def initialize_options(self):
         pass
 
     def finalize_options(self):
         pass
 
     def run(self):
         if os.path.exists(self._indexfilename):
             with open(self._indexfilename, 'w') as f:
                 f.write('# empty\n')
 
         # here no extension enabled, disabled() lists up everything
         code = (
             'import pprint; from mercurial import extensions; '
             'ext = extensions.disabled();'
             'ext.pop("__index__", None);'
             'pprint.pprint(ext)'
         )
         returncode, out, err = runcmd(
             [sys.executable, '-c', code], localhgenv()
         )
         if err or returncode != 0:
             raise DistutilsExecError(err)
 
         with open(self._indexfilename, 'wb') as f:
             f.write(b'# this file is autogenerated by setup.py\n')
             f.write(b'docs = ')
             f.write(out)
 
 
 class buildhgexe(build_ext):
     description = 'compile hg.exe from mercurial/exewrapper.c'
     user_options = build_ext.user_options + [
         (
             'long-paths-support',
             None,
             'enable support for long paths on '
             'Windows (off by default and '
             'experimental)',
         ),
     ]
 
     LONG_PATHS_MANIFEST = """
     <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
     <assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0">
         <application>
             <windowsSettings
             xmlns:ws2="http://schemas.microsoft.com/SMI/2016/WindowsSettings">
                 <ws2:longPathAware>true</ws2:longPathAware>
             </windowsSettings>
         </application>
     </assembly>"""
 
     def initialize_options(self):
         build_ext.initialize_options(self)
         self.long_paths_support = False
 
     def build_extensions(self):
         if os.name != 'nt':
             return
         if isinstance(self.compiler, HackedMingw32CCompiler):
             self.compiler.compiler_so = self.compiler.compiler  # no -mdll
             self.compiler.dll_libraries = []  # no -lmsrvc90
 
         pythonlib = None
 
         if getattr(sys, 'dllhandle', None):
             # Different Python installs can have different Python library
             # names. e.g. the official CPython distribution uses pythonXY.dll
             # and MinGW uses libpythonX.Y.dll.
             _kernel32 = ctypes.windll.kernel32
             _kernel32.GetModuleFileNameA.argtypes = [
                 ctypes.c_void_p,
                 ctypes.c_void_p,
                 ctypes.c_ulong,
             ]
             _kernel32.GetModuleFileNameA.restype = ctypes.c_ulong
             size = 1000
             buf = ctypes.create_string_buffer(size + 1)
             filelen = _kernel32.GetModuleFileNameA(
                 sys.dllhandle, ctypes.byref(buf), size
             )
 
             if filelen > 0 and filelen != size:
                 dllbasename = os.path.basename(buf.value)
                 if not dllbasename.lower().endswith(b'.dll'):
                     raise SystemExit(
                         'Python DLL does not end with .dll: %s' % dllbasename
                     )
                 pythonlib = dllbasename[:-4]
 
         if not pythonlib:
             log.warn(
                 'could not determine Python DLL filename; assuming pythonXY'
             )
 
             hv = sys.hexversion
             pythonlib = b'python%d%d' % (hv >> 24, (hv >> 16) & 0xFF)
 
         log.info('using %s as Python library name' % pythonlib)
         with open('mercurial/hgpythonlib.h', 'wb') as f:
             f.write(b'/* this file is autogenerated by setup.py */\n')
             f.write(b'#define HGPYTHONLIB "%s"\n' % pythonlib)
 
         macros = None
         if sys.version_info[0] >= 3:
             macros = [('_UNICODE', None), ('UNICODE', None)]
 
         objects = self.compiler.compile(
             ['mercurial/exewrapper.c'],
             output_dir=self.build_temp,
             macros=macros,
         )
         dir = os.path.dirname(self.get_ext_fullpath('dummy'))
         self.hgtarget = os.path.join(dir, 'hg')
         self.compiler.link_executable(
             objects, self.hgtarget, libraries=[], output_dir=self.build_temp
         )
         if self.long_paths_support:
             self.addlongpathsmanifest()
 
     def addlongpathsmanifest(self):
         r"""Add manifest pieces so that hg.exe understands long paths
 
         This is an EXPERIMENTAL feature, use with care.
         To enable long paths support, one needs to do two things:
         - build Mercurial with --long-paths-support option
         - change HKLM\SYSTEM\CurrentControlSet\Control\FileSystem\
                  LongPathsEnabled to have value 1.
 
         Please ignore 'warning 81010002: Unrecognized Element "longPathAware"';
         it happens because Mercurial uses mt.exe circa 2008, which is not
         yet aware of long paths support in the manifest (I think so at least).
         This does not stop mt.exe from embedding/merging the XML properly.
 
         Why resource #1 should be used for .exe manifests? I don't know and
         wasn't able to find an explanation for mortals. But it seems to work.
         """
         exefname = self.compiler.executable_filename(self.hgtarget)
         fdauto, manfname = tempfile.mkstemp(suffix='.hg.exe.manifest')
         os.close(fdauto)
         with open(manfname, 'w') as f:
             f.write(self.LONG_PATHS_MANIFEST)
         log.info("long paths manifest is written to '%s'" % manfname)
         inputresource = '-inputresource:%s;#1' % exefname
         outputresource = '-outputresource:%s;#1' % exefname
         log.info("running mt.exe to update hg.exe's manifest in-place")
         # supplying both -manifest and -inputresource to mt.exe makes
         # it merge the embedded and supplied manifests in the -outputresource
         self.spawn(
             [
                 'mt.exe',
                 '-nologo',
                 '-manifest',
                 manfname,
                 inputresource,
                 outputresource,
             ]
         )
         log.info("done updating hg.exe's manifest")
         os.remove(manfname)
 
     @property
     def hgexepath(self):
         dir = os.path.dirname(self.get_ext_fullpath('dummy'))
         return os.path.join(self.build_temp, dir, 'hg.exe')
 
 
 class hgbuilddoc(Command):
     description = 'build documentation'
     user_options = [
         ('man', None, 'generate man pages'),
         ('html', None, 'generate html pages'),
     ]
 
     def initialize_options(self):
         self.man = None
         self.html = None
 
     def finalize_options(self):
         # If --man or --html are set, only generate what we're told to.
         # Otherwise generate everything.
         have_subset = self.man is not None or self.html is not None
 
         if have_subset:
             self.man = True if self.man else False
             self.html = True if self.html else False
         else:
             self.man = True
             self.html = True
 
     def run(self):
         def normalizecrlf(p):
             with open(p, 'rb') as fh:
                 orig = fh.read()
 
             if b'\r\n' not in orig:
                 return
 
             log.info('normalizing %s to LF line endings' % p)
             with open(p, 'wb') as fh:
                 fh.write(orig.replace(b'\r\n', b'\n'))
 
         def gentxt(root):
             txt = 'doc/%s.txt' % root
             log.info('generating %s' % txt)
             res, out, err = runcmd(
                 [sys.executable, 'gendoc.py', root], os.environ, cwd='doc'
             )
             if res:
                 raise SystemExit(
                     'error running gendoc.py: %s' % '\n'.join([out, err])
                 )
 
             with open(txt, 'wb') as fh:
                 fh.write(out)
 
         def gengendoc(root):
             gendoc = 'doc/%s.gendoc.txt' % root
 
             log.info('generating %s' % gendoc)
             res, out, err = runcmd(
                 [sys.executable, 'gendoc.py', '%s.gendoc' % root],
                 os.environ,
                 cwd='doc',
             )
             if res:
                 raise SystemExit(
                     'error running gendoc: %s' % '\n'.join([out, err])
                 )
 
             with open(gendoc, 'wb') as fh:
                 fh.write(out)
 
         def genman(root):
             log.info('generating doc/%s' % root)
             res, out, err = runcmd(
                 [
                     sys.executable,
                     'runrst',
                     'hgmanpage',
                     '--halt',
                     'warning',
                     '--strip-elements-with-class',
                     'htmlonly',
                     '%s.txt' % root,
                     root,
                 ],
                 os.environ,
                 cwd='doc',
             )
             if res:
                 raise SystemExit(
                     'error running runrst: %s' % '\n'.join([out, err])
                 )
 
             normalizecrlf('doc/%s' % root)
 
         def genhtml(root):
             log.info('generating doc/%s.html' % root)
             res, out, err = runcmd(
                 [
                     sys.executable,
                     'runrst',
                     'html',
                     '--halt',
                     'warning',
                     '--link-stylesheet',
                     '--stylesheet-path',
                     'style.css',
                     '%s.txt' % root,
                     '%s.html' % root,
                 ],
                 os.environ,
                 cwd='doc',
             )
             if res:
                 raise SystemExit(
                     'error running runrst: %s' % '\n'.join([out, err])
                 )
 
             normalizecrlf('doc/%s.html' % root)
 
         # This logic is duplicated in doc/Makefile.
         sources = {
             f
             for f in os.listdir('mercurial/helptext')
             if re.search(r'[0-9]\.txt$', f)
         }
 
         # common.txt is a one-off.
         gentxt('common')
 
         for source in sorted(sources):
             assert source[-4:] == '.txt'
             root = source[:-4]
 
             gentxt(root)
             gengendoc(root)
 
             if self.man:
                 genman(root)
             if self.html:
                 genhtml(root)
 
 
 class hginstall(install):
 
     user_options = install.user_options + [
         (
             'old-and-unmanageable',
             None,
             'noop, present for eggless setuptools compat',
         ),
         (
             'single-version-externally-managed',
             None,
             'noop, present for eggless setuptools compat',
         ),
     ]
 
     # Also helps setuptools not be sad while we refuse to create eggs.
     single_version_externally_managed = True
 
     def get_sub_commands(self):
         # Screen out egg related commands to prevent egg generation.  But allow
         # mercurial.egg-info generation, since that is part of modern
         # packaging.
         excl = {'bdist_egg'}
         return filter(lambda x: x not in excl, install.get_sub_commands(self))
 
 
 class hginstalllib(install_lib):
     '''
     This is a specialization of install_lib that replaces the copy_file used
     there so that it supports setting the mode of files after copying them,
     instead of just preserving the mode that the files originally had.  If your
     system has a umask of something like 027, preserving the permissions when
     copying will lead to a broken install.
 
     Note that just passing keep_permissions=False to copy_file would be
     insufficient, as it might still be applying a umask.
     '''
 
     def run(self):
         realcopyfile = file_util.copy_file
 
         def copyfileandsetmode(*args, **kwargs):
             src, dst = args[0], args[1]
             dst, copied = realcopyfile(*args, **kwargs)
             if copied:
                 st = os.stat(src)
                 # Persist executable bit (apply it to group and other if user
                 # has it)
                 if st[stat.ST_MODE] & stat.S_IXUSR:
                     setmode = int('0755', 8)
                 else:
                     setmode = int('0644', 8)
                 m = stat.S_IMODE(st[stat.ST_MODE])
                 m = (m & ~int('0777', 8)) | setmode
                 os.chmod(dst, m)
 
         file_util.copy_file = copyfileandsetmode
         try:
             install_lib.run(self)
         finally:
             file_util.copy_file = realcopyfile
 
 
 class hginstallscripts(install_scripts):
     '''
     This is a specialization of install_scripts that replaces the @LIBDIR@ with
     the configured directory for modules. If possible, the path is made relative
     to the directory for scripts.
     '''
 
     def initialize_options(self):
         install_scripts.initialize_options(self)
 
         self.install_lib = None
 
     def finalize_options(self):
         install_scripts.finalize_options(self)
         self.set_undefined_options('install', ('install_lib', 'install_lib'))
 
     def run(self):
         install_scripts.run(self)
 
         # It only makes sense to replace @LIBDIR@ with the install path if
         # the install path is known. For wheels, the logic below calculates
         # the libdir to be "../..". This is because the internal layout of a
         # wheel archive looks like:
         #
         #   mercurial-3.6.1.data/scripts/hg
         #   mercurial/__init__.py
         #
         # When installing wheels, the subdirectories of the "<pkg>.data"
         # directory are translated to system local paths and files therein
         # are copied in place. The mercurial/* files are installed into the
         # site-packages directory. However, the site-packages directory
         # isn't known until wheel install time. This means we have no clue
         # at wheel generation time what the installed site-packages directory
         # will be. And, wheels don't appear to provide the ability to register
         # custom code to run during wheel installation. This all means that
         # we can't reliably set the libdir in wheels: the default behavior
         # of looking in sys.path must do.
 
         if (
             os.path.splitdrive(self.install_dir)[0]
             != os.path.splitdrive(self.install_lib)[0]
         ):
             # can't make relative paths from one drive to another, so use an
             # absolute path instead
             libdir = self.install_lib
         else:
             libdir = os.path.relpath(self.install_lib, self.install_dir)
 
         for outfile in self.outfiles:
             with open(outfile, 'rb') as fp:
                 data = fp.read()
 
             # skip binary files
             if b'\0' in data:
                 continue
 
             # During local installs, the shebang will be rewritten to the final
             # install path. During wheel packaging, the shebang has a special
             # value.
             if data.startswith(b'#!python'):
                 log.info(
                     'not rewriting @LIBDIR@ in %s because install path '
                     'not known' % outfile
                 )
                 continue
 
             data = data.replace(b'@LIBDIR@', libdir.encode(libdir_escape))
             with open(outfile, 'wb') as fp:
                 fp.write(data)
 
 
 # virtualenv installs custom distutils/__init__.py and
 # distutils/distutils.cfg files which essentially proxy back to the
 # "real" distutils in the main Python install. The presence of this
 # directory causes py2exe to pick up the "hacked" distutils package
 # from the virtualenv and "import distutils" will fail from the py2exe
 # build because the "real" distutils files can't be located.
 #
 # We work around this by monkeypatching the py2exe code finding Python
 # modules to replace the found virtualenv distutils modules with the
 # original versions via filesystem scanning. This is a bit hacky. But
 # it allows us to use virtualenvs for py2exe packaging, which is more
 # deterministic and reproducible.
 #
 # It's worth noting that the common StackOverflow suggestions for this
 # problem involve copying the original distutils files into the
 # virtualenv or into the staging directory after setup() is invoked.
 # The former is very brittle and can easily break setup(). Our hacking
 # of the found modules routine has a similar result as copying the files
 # manually. But it makes fewer assumptions about how py2exe works and
 # is less brittle.
 
 # This only catches virtualenvs made with virtualenv (as opposed to
 # venv, which is likely what Python 3 uses).
 py2exehacked = py2exeloaded and getattr(sys, 'real_prefix', None) is not None
 
 if py2exehacked:
     from distutils.command.py2exe import py2exe as buildpy2exe
     from py2exe.mf import Module as py2exemodule
 
     class hgbuildpy2exe(buildpy2exe):
         def find_needed_modules(self, mf, files, modules):
             res = buildpy2exe.find_needed_modules(self, mf, files, modules)
 
             # Replace virtualenv's distutils modules with the real ones.
             modules = {}
             for k, v in res.modules.items():
                 if k != 'distutils' and not k.startswith('distutils.'):
                     modules[k] = v
 
             res.modules = modules
 
             import opcode
 
             distutilsreal = os.path.join(
                 os.path.dirname(opcode.__file__), 'distutils'
             )
 
             for root, dirs, files in os.walk(distutilsreal):
                 for f in sorted(files):
                     if not f.endswith('.py'):
                         continue
 
                     full = os.path.join(root, f)
 
                     parents = ['distutils']
 
                     if root != distutilsreal:
                         rel = os.path.relpath(root, distutilsreal)
                         parents.extend(p for p in rel.split(os.sep))
 
                     modname = '%s.%s' % ('.'.join(parents), f[:-3])
 
                     if modname.startswith('distutils.tests.'):
                         continue
 
                     if modname.endswith('.__init__'):
                         modname = modname[: -len('.__init__')]
                         path = os.path.dirname(full)
                     else:
                         path = None
 
                     res.modules[modname] = py2exemodule(
                         modname, full, path=path
                     )
 
             if 'distutils' not in res.modules:
                 raise SystemExit('could not find distutils modules')
 
             return res
 
 
 cmdclass = {
     'build': hgbuild,
     'build_doc': hgbuilddoc,
     'build_mo': hgbuildmo,
     'build_ext': hgbuildext,
     'build_py': hgbuildpy,
     'build_scripts': hgbuildscripts,
     'build_hgextindex': buildhgextindex,
     'install': hginstall,
     'install_lib': hginstalllib,
     'install_scripts': hginstallscripts,
     'build_hgexe': buildhgexe,
 }
 
 if py2exehacked:
     cmdclass['py2exe'] = hgbuildpy2exe
 
 packages = [
     'mercurial',
     'mercurial.cext',
     'mercurial.cffi',
     'mercurial.defaultrc',
     'mercurial.helptext',
     'mercurial.helptext.internals',
     'mercurial.hgweb',
     'mercurial.interfaces',
     'mercurial.pure',
     'mercurial.thirdparty',
     'mercurial.thirdparty.attr',
     'mercurial.thirdparty.zope',
     'mercurial.thirdparty.zope.interface',
     'mercurial.utils',
     'mercurial.revlogutils',
     'mercurial.testing',
     'hgext',
     'hgext.convert',
     'hgext.fsmonitor',
     'hgext.fastannotate',
     'hgext.fsmonitor.pywatchman',
+    'hgext.git',
     'hgext.highlight',
     'hgext.hooklib',
     'hgext.infinitepush',
     'hgext.largefiles',
     'hgext.lfs',
     'hgext.narrow',
     'hgext.remotefilelog',
     'hgext.zeroconf',
     'hgext3rd',
     'hgdemandimport',
 ]
 if sys.version_info[0] == 2:
     packages.extend(
         [
             'mercurial.thirdparty.concurrent',
             'mercurial.thirdparty.concurrent.futures',
         ]
     )
 
 if 'HG_PY2EXE_EXTRA_INSTALL_PACKAGES' in os.environ:
     # py2exe can't cope with namespace packages very well, so we have to
     # install any hgext3rd.* extensions that we want in the final py2exe
     # image here. This is gross, but you gotta do what you gotta do.
     packages.extend(os.environ['HG_PY2EXE_EXTRA_INSTALL_PACKAGES'].split(' '))
 
 common_depends = [
     'mercurial/bitmanipulation.h',
     'mercurial/compat.h',
     'mercurial/cext/util.h',
 ]
 common_include_dirs = ['mercurial']
 
 osutil_cflags = []
 osutil_ldflags = []
 
 # platform specific macros
 for plat, func in [('bsd', 'setproctitle')]:
     if re.search(plat, sys.platform) and hasfunction(new_compiler(), func):
         osutil_cflags.append('-DHAVE_%s' % func.upper())
 
 for plat, macro, code in [
     (
         'bsd|darwin',
         'BSD_STATFS',
         '''
      #include <sys/param.h>
      #include <sys/mount.h>
      int main() { struct statfs s; return sizeof(s.f_fstypename); }
      ''',
     ),
     (
         'linux',
         'LINUX_STATFS',
         '''
      #include <linux/magic.h>
      #include <sys/vfs.h>
      int main() { struct statfs s; return sizeof(s.f_type); }
      ''',
     ),
 ]:
     if re.search(plat, sys.platform) and cancompile(new_compiler(), code):
         osutil_cflags.append('-DHAVE_%s' % macro)
 
 if sys.platform == 'darwin':
     osutil_ldflags += ['-framework', 'ApplicationServices']
 
 xdiff_srcs = [
     'mercurial/thirdparty/xdiff/xdiffi.c',
     'mercurial/thirdparty/xdiff/xprepare.c',
     'mercurial/thirdparty/xdiff/xutils.c',
 ]
 
 xdiff_headers = [
     'mercurial/thirdparty/xdiff/xdiff.h',
     'mercurial/thirdparty/xdiff/xdiffi.h',
     'mercurial/thirdparty/xdiff/xinclude.h',
     'mercurial/thirdparty/xdiff/xmacros.h',
     'mercurial/thirdparty/xdiff/xprepare.h',
     'mercurial/thirdparty/xdiff/xtypes.h',
     'mercurial/thirdparty/xdiff/xutils.h',
 ]
 
 
 class RustCompilationError(CCompilerError):
     """Exception class for Rust compilation errors."""
 
 
 class RustExtension(Extension):
     """Base classes for concrete Rust Extension classes.
     """
 
     rusttargetdir = os.path.join('rust', 'target', 'release')
 
     def __init__(
         self, mpath, sources, rustlibname, subcrate, py3_features=None, **kw
     ):
         Extension.__init__(self, mpath, sources, **kw)
         srcdir = self.rustsrcdir = os.path.join('rust', subcrate)
         self.py3_features = py3_features
 
         # adding Rust source and control files to depends so that the extension
         # gets rebuilt if they've changed
         self.depends.append(os.path.join(srcdir, 'Cargo.toml'))
         cargo_lock = os.path.join(srcdir, 'Cargo.lock')
         if os.path.exists(cargo_lock):
             self.depends.append(cargo_lock)
         for dirpath, subdir, fnames in os.walk(os.path.join(srcdir, 'src')):
             self.depends.extend(
                 os.path.join(dirpath, fname)
                 for fname in fnames
                 if os.path.splitext(fname)[1] == '.rs'
             )
 
     @staticmethod
     def rustdylibsuffix():
         """Return the suffix for shared libraries produced by rustc.
 
         See also: https://doc.rust-lang.org/reference/linkage.html
         """
         if sys.platform == 'darwin':
             return '.dylib'
         elif os.name == 'nt':
             return '.dll'
         else:
             return '.so'
 
     def rustbuild(self):
         env = os.environ.copy()
         if 'HGTEST_RESTOREENV' in env:
             # Mercurial tests change HOME to a temporary directory,
             # but, if installed with rustup, the Rust toolchain needs
             # HOME to be correct (otherwise the 'no default toolchain'
             # error message is issued and the build fails).
             # This happens currently with test-hghave.t, which does
             # invoke this build.
 
             # Unix only fix (os.path.expanduser not really reliable if
             # HOME is shadowed like this)
             import pwd
 
             env['HOME'] = pwd.getpwuid(os.getuid()).pw_dir
 
         cargocmd = ['cargo', 'rustc', '-vv', '--release']
 
         feature_flags = []
 
         if sys.version_info[0] == 3 and self.py3_features is not None:
             feature_flags.append(self.py3_features)
             cargocmd.append('--no-default-features')
 
         rust_features = env.get("HG_RUST_FEATURES")
         if rust_features:
             feature_flags.append(rust_features)
 
         cargocmd.extend(('--features', " ".join(feature_flags)))
 
         cargocmd.append('--')
         if sys.platform == 'darwin':
             cargocmd.extend(
                 ("-C", "link-arg=-undefined", "-C", "link-arg=dynamic_lookup")
             )
         try:
             subprocess.check_call(cargocmd, env=env, cwd=self.rustsrcdir)
         except OSError as exc:
             if exc.errno == errno.ENOENT:
                 raise RustCompilationError("Cargo not found")
             elif exc.errno == errno.EACCES:
                 raise RustCompilationError(
                     "Cargo found, but permisssion to execute it is denied"
                 )
             else:
                 raise
         except subprocess.CalledProcessError:
             raise RustCompilationError(
                 "Cargo failed. Working directory: %r, "
                 "command: %r, environment: %r"
                 % (self.rustsrcdir, cargocmd, env)
             )
 
 
 class RustEnhancedExtension(RustExtension):
     """A C Extension, conditionally enhanced with Rust code.
 
     If the HGWITHRUSTEXT environment variable is set to something else
     than 'cpython', the Rust sources get compiled and linked within
     the C target shared library object.
     """
 
     def __init__(self, mpath, sources, rustlibname, subcrate, **kw):
         RustExtension.__init__(
             self, mpath, sources, rustlibname, subcrate, **kw
         )
         if hgrustext != 'direct-ffi':
             return
         self.extra_compile_args.append('-DWITH_RUST')
         self.libraries.append(rustlibname)
         self.library_dirs.append(self.rusttargetdir)
 
     def rustbuild(self):
         if hgrustext == 'direct-ffi':
             RustExtension.rustbuild(self)
 
 
 class RustStandaloneExtension(RustExtension):
     def __init__(self, pydottedname, rustcrate, dylibname, **kw):
         RustExtension.__init__(
             self, pydottedname, [], dylibname, rustcrate, **kw
         )
         self.dylibname = dylibname
 
     def build(self, target_dir):
         self.rustbuild()
         target = [target_dir]
         target.extend(self.name.split('.'))
         target[-1] += DYLIB_SUFFIX
         shutil.copy2(
             os.path.join(
                 self.rusttargetdir, self.dylibname + self.rustdylibsuffix()
             ),
             os.path.join(*target),
         )
 
 
 extmodules = [
     Extension(
         'mercurial.cext.base85',
         ['mercurial/cext/base85.c'],
         include_dirs=common_include_dirs,
         depends=common_depends,
     ),
     Extension(
         'mercurial.cext.bdiff',
         ['mercurial/bdiff.c', 'mercurial/cext/bdiff.c'] + xdiff_srcs,
         include_dirs=common_include_dirs,
         depends=common_depends + ['mercurial/bdiff.h'] + xdiff_headers,
     ),
     Extension(
         'mercurial.cext.mpatch',
         ['mercurial/mpatch.c', 'mercurial/cext/mpatch.c'],
         include_dirs=common_include_dirs,
         depends=common_depends,
     ),
     RustEnhancedExtension(
         'mercurial.cext.parsers',
         [
             'mercurial/cext/charencode.c',
             'mercurial/cext/dirs.c',
             'mercurial/cext/manifest.c',
             'mercurial/cext/parsers.c',
             'mercurial/cext/pathencode.c',
             'mercurial/cext/revlog.c',
         ],
         'hgdirectffi',
         'hg-direct-ffi',
         include_dirs=common_include_dirs,
         depends=common_depends
         + [
             'mercurial/cext/charencode.h',
             'mercurial/cext/revlog.h',
             'rust/hg-core/src/ancestors.rs',
             'rust/hg-core/src/lib.rs',
         ],
     ),
     Extension(
         'mercurial.cext.osutil',
         ['mercurial/cext/osutil.c'],
         include_dirs=common_include_dirs,
         extra_compile_args=osutil_cflags,
         extra_link_args=osutil_ldflags,
         depends=common_depends,
     ),
     Extension(
         'mercurial.thirdparty.zope.interface._zope_interface_coptimizations',
         [
             'mercurial/thirdparty/zope/interface/_zope_interface_coptimizations.c',
         ],
     ),
     Extension(
         'mercurial.thirdparty.sha1dc',
         [
             'mercurial/thirdparty/sha1dc/cext.c',
             'mercurial/thirdparty/sha1dc/lib/sha1.c',
             'mercurial/thirdparty/sha1dc/lib/ubc_check.c',
         ],
     ),
     Extension(
         'hgext.fsmonitor.pywatchman.bser', ['hgext/fsmonitor/pywatchman/bser.c']
     ),
     RustStandaloneExtension(
         'mercurial.rustext', 'hg-cpython', 'librusthg', py3_features='python3'
     ),
 ]
 
 
 sys.path.insert(0, 'contrib/python-zstandard')
 import setup_zstd
 
 extmodules.append(
     setup_zstd.get_c_extension(
         name='mercurial.zstd', root=os.path.abspath(os.path.dirname(__file__))
     )
 )
 
 try:
     from distutils import cygwinccompiler
 
     # the -mno-cygwin option has been deprecated for years
     mingw32compilerclass = cygwinccompiler.Mingw32CCompiler
 
     class HackedMingw32CCompiler(cygwinccompiler.Mingw32CCompiler):
         def __init__(self, *args, **kwargs):
             mingw32compilerclass.__init__(self, *args, **kwargs)
             for i in 'compiler compiler_so linker_exe linker_so'.split():
                 try:
                     getattr(self, i).remove('-mno-cygwin')
                 except ValueError:
                     pass
 
     cygwinccompiler.Mingw32CCompiler = HackedMingw32CCompiler
 except ImportError:
     # the cygwinccompiler package is not available on some Python
     # distributions like the ones from the optware project for Synology
     # DiskStation boxes
     class HackedMingw32CCompiler(object):
         pass
 
 
 if os.name == 'nt':
     # Allow compiler/linker flags to be added to Visual Studio builds.  Passing
     # extra_link_args to distutils.extensions.Extension() doesn't have any
     # effect.
     from distutils import msvccompiler
 
     msvccompilerclass = msvccompiler.MSVCCompiler
 
     class HackedMSVCCompiler(msvccompiler.MSVCCompiler):
         def initialize(self):
             msvccompilerclass.initialize(self)
             # "warning LNK4197: export 'func' specified multiple times"
             self.ldflags_shared.append('/ignore:4197')
             self.ldflags_shared_debug.append('/ignore:4197')
 
     msvccompiler.MSVCCompiler = HackedMSVCCompiler
 
 packagedata = {
     'mercurial': [
         'locale/*/LC_MESSAGES/hg.mo',
         'defaultrc/*.rc',
         'dummycert.pem',
     ],
     'mercurial.helptext': ['*.txt',],
     'mercurial.helptext.internals': ['*.txt',],
 }
 
 
 def ordinarypath(p):
     return p and p[0] != '.' and p[-1] != '~'
 
 
 for root in ('templates',):
     for curdir, dirs, files in os.walk(os.path.join('mercurial', root)):
         curdir = curdir.split(os.sep, 1)[1]
         dirs[:] = filter(ordinarypath, dirs)
         for f in filter(ordinarypath, files):
             f = os.path.join(curdir, f)
             packagedata['mercurial'].append(f)
 
 datafiles = []
 
 # distutils expects version to be str/unicode. Converting it to
 # unicode on Python 2 still works because it won't contain any
 # non-ascii bytes and will be implicitly converted back to bytes
 # when operated on.
 assert isinstance(version, bytes)
 setupversion = version.decode('ascii')
 
 extra = {}
 
 py2exepackages = [
     'hgdemandimport',
     'hgext3rd',
     'hgext',
     'email',
     # implicitly imported per module policy
     # (cffi wouldn't be used as a frozen exe)
     'mercurial.cext',
     #'mercurial.cffi',
     'mercurial.pure',
 ]
 
 py2exeexcludes = []
 py2exedllexcludes = ['crypt32.dll']
 
 if issetuptools:
     extra['python_requires'] = supportedpy
 
 if py2exeloaded:
     extra['console'] = [
         {
             'script': 'hg',
             'copyright': 'Copyright (C) 2005-2020 Matt Mackall and others',
             'product_version': version,
         }
     ]
     # Sub command of 'build' because 'py2exe' does not handle sub_commands.
     # Need to override hgbuild because it has a private copy of
     # build.sub_commands.
     hgbuild.sub_commands.insert(0, ('build_hgextindex', None))
     # put dlls in sub directory so that they won't pollute PATH
     extra['zipfile'] = 'lib/library.zip'
 
     # We allow some configuration to be supplemented via environment
     # variables. This is better than setup.cfg files because it allows
     # supplementing configs instead of replacing them.
     extrapackages = os.environ.get('HG_PY2EXE_EXTRA_PACKAGES')
     if extrapackages:
         py2exepackages.extend(extrapackages.split(' '))
 
     excludes = os.environ.get('HG_PY2EXE_EXTRA_EXCLUDES')
     if excludes:
         py2exeexcludes.extend(excludes.split(' '))
 
     dllexcludes = os.environ.get('HG_PY2EXE_EXTRA_DLL_EXCLUDES')
     if dllexcludes:
         py2exedllexcludes.extend(dllexcludes.split(' '))
 
 if os.name == 'nt':
     # Windows binary file versions for exe/dll files must have the
     # form W.X.Y.Z, where W,X,Y,Z are numbers in the range 0..65535
     setupversion = setupversion.split(r'+', 1)[0]
 
 if sys.platform == 'darwin' and os.path.exists('/usr/bin/xcodebuild'):
     version = runcmd(['/usr/bin/xcodebuild', '-version'], {})[1].splitlines()
     if version:
         version = version[0]
         if sys.version_info[0] == 3:
             version = version.decode('utf-8')
         xcode4 = version.startswith('Xcode') and StrictVersion(
             version.split()[1]
         ) >= StrictVersion('4.0')
         xcode51 = re.match(r'^Xcode\s+5\.1', version) is not None
     else:
         # xcodebuild returns empty on OS X Lion with XCode 4.3 not
         # installed, but instead with only command-line tools. Assume
         # that only happens on >= Lion, thus no PPC support.
         xcode4 = True
         xcode51 = False
 
     # XCode 4.0 dropped support for ppc architecture, which is hardcoded in
     # distutils.sysconfig
     if xcode4:
         os.environ['ARCHFLAGS'] = ''
 
     # XCode 5.1 changes clang such that it now fails to compile if the
     # -mno-fused-madd flag is passed, but the version of Python shipped with
     # OS X 10.9 Mavericks includes this flag. This causes problems in all
     # C extension modules, and a bug has been filed upstream at
     # http://bugs.python.org/issue21244. We also need to patch this here
     # so Mercurial can continue to compile in the meantime.
     if xcode51:
         cflags = get_config_var('CFLAGS')
         if cflags and re.search(r'-mno-fused-madd\b', cflags) is not None:
             os.environ['CFLAGS'] = (
                 os.environ.get('CFLAGS', '') + ' -Qunused-arguments'
             )
 
 setup(
     name='mercurial',
     version=setupversion,
     author='Matt Mackall and many others',
     author_email='[e-mail]',
     url='https://mercurial-scm.org/',
     download_url='https://mercurial-scm.org/release/',
     description=(
         'Fast scalable distributed SCM (revision control, version '
         'control) system'
     ),
     long_description=(
         'Mercurial is a distributed SCM tool written in Python.'
         ' It is used by a number of large projects that require'
         ' fast, reliable distributed revision control, such as '
         'Mozilla.'
     ),
     license='GNU GPLv2 or any later version',
     classifiers=[
         'Development Status :: 6 - Mature',
         'Environment :: Console',
         'Intended Audience :: Developers',
         'Intended Audience :: System Administrators',
         'License :: OSI Approved :: GNU General Public License (GPL)',
         'Natural Language :: Danish',
         'Natural Language :: English',
         'Natural Language :: German',
         'Natural Language :: Italian',
         'Natural Language :: Japanese',
         'Natural Language :: Portuguese (Brazilian)',
         'Operating System :: Microsoft :: Windows',
         'Operating System :: OS Independent',
         'Operating System :: POSIX',
         'Programming Language :: C',
         'Programming Language :: Python',
         'Topic :: Software Development :: Version Control',
     ],
     scripts=scripts,
     packages=packages,
     ext_modules=extmodules,
     data_files=datafiles,
     package_data=packagedata,
     cmdclass=cmdclass,
     distclass=hgdist,
     options={
         'py2exe': {
             'bundle_files': 3,
             'dll_excludes': py2exedllexcludes,
             'excludes': py2exeexcludes,
             'packages': py2exepackages,
         },
         'bdist_mpkg': {
             'zipdist': False,
             'license': 'COPYING',
             'readme': 'contrib/packaging/macosx/Readme.html',
             'welcome': 'contrib/packaging/macosx/Welcome.html',
         },
     },
     **extra
 )