rust: update the minimum version of Rust

Debian Bullseye has just been released, and it carries `rustc 1.48.0`.

This actually implies a regression that we can't really do anything about in
`rhg`. See https://github.com/rust-lang/rust/issues/88825. In short, closed (or
bad) standard file descriptors are reopened silently with no way of telling by
the Rust runtime before `main` is executed. This means that closed fds are not
forwarded to the subprocess we run in case of fallback. This is a bit sad, but
probably not something worth worrying too much about.

Differential Revision: https://phab.mercurial-scm.org/D11341

rust/README.rst

@@ -1,121 +1,121 b''
 ===================
 Mercurial Rust Code
 ===================
 
 This directory contains various Rust code for the Mercurial project.
 Rust is not required to use (or build) Mercurial, but using it
 improves performance in some areas.
 
 There are currently three independent rust projects:
 - chg. An implementation of chg, in rust instead of C.
 - hgcli. A project that provide a (mostly) self-contained "hg" binary,
   for ease of deployment and a bit of speed, using PyOxidizer. See
   hgcli/README.md.
 - hg-core (and hg-cpython): implementation of some
   functionality of mercurial in rust, e.g. ancestry computations in
   revision graphs, status or pull discovery. The top-level ``Cargo.toml`` file
   defines a workspace containing these crates.
 
 Using Rust code
 ===============
 
 Local use (you need to clean previous build artifacts if you have
 built without rust previously)::
 
   $ make PURE=--rust local # to use ./hg
   $ ./tests/run-tests.py --rust # to run all tests
   $ ./hg debuginstall | grep -i rust # to validate rust is in use
   checking Rust extensions (installed)
   checking module policy (rust+c-allow)
 
 If the environment variable ``HGWITHRUSTEXT=cpython`` is set, the Rust
 extension will be used by default unless ``--no-rust``.
 
 One day we may use this environment variable to switch to new experimental
 binding crates like a hypothetical ``HGWITHRUSTEXT=hpy``.
 
 Special features
 ================
 
 You might want to check the `features` section in ``hg-cpython/Cargo.toml``.
 It may contain features that might be interesting to try out.
 
 To use features from the Makefile, use the `HG_RUST_FEATURES` environment
 variable: for instance `HG_RUST_FEATURES="some-feature other-feature"`
 
 Profiling
 =========
 
 Setting the environment variable ``RUST_LOG=trace`` will make hg print
 a few high level rust-related performance numbers. It can also
 indicate why the rust code cannot be used (say, using lookarounds in
 hgignore).
 
 Creating a ``.cargo/config`` file with the following content enables
 debug information in optimized builds. This make profiles more informative
 with source file name and line number for Rust stack frames and
 (in some cases) stack frames for Rust functions that have been inlined.
 
   [profile.release]
   debug = true
 
 ``py-spy`` (https://github.com/benfred/py-spy) can be used to
 construct a single profile with rust functions and python functions
 (as opposed to ``hg --profile``, which attributes time spent in rust
 to some unlucky python code running shortly after the rust code, and
 as opposed to tools for native code like ``perf``, which attribute
 time to the python interpreter instead of python functions).
 
 Example usage:
 
   $ make PURE=--rust local # Don't forget to recompile after a code change
   $ py-spy record --native --output /tmp/profile.svg -- ./hg ...
 
 Developing Rust
 ===============
 
-The current version of Rust in use is ``1.41.1``, because it's what Debian
-stable has. You can use ``rustup override set 1.41.1`` at the root of the repo
+The current version of Rust in use is ``1.48.0``, because it's what Debian
+stable has. You can use ``rustup override set 1.48.0`` at the root of the repo
 to make it easier on you.
 
 Go to the ``hg-cpython`` folder::
 
   $ cd rust/hg-cpython
 
 Or, only the ``hg-core`` folder. Be careful not to break compatibility::
 
   $ cd rust/hg-core
 
 Simply run::
 
    $ cargo build --release
 
 It is possible to build without ``--release``, but it is not
 recommended if performance is of any interest: there can be an order
 of magnitude of degradation when removing ``--release``.
 
 For faster builds, you may want to skip code generation::
 
   $ cargo check
 
 For even faster typing::
 
   $ cargo c
 
 You can run only the rust-specific tests (as opposed to tests of
 mercurial as a whole) with::
 
   $ cargo test --all
 
 Formatting the code
 -------------------
 
 We use ``rustfmt`` to keep the code formatted at all times. For now, we are
 using the nightly version because it has been stable enough and provides
 comment folding.
 
 To format the entire Rust workspace::
 
   $ cargo +nightly fmt
 
 This requires you to have the nightly toolchain installed.

tests/test-basic.t

@@ -1,257 +1,258 b''
 Create a repository:
 
 #if no-extraextensions
   $ hg config
   chgserver.idletimeout=60
   devel.all-warnings=true
   devel.default-date=0 0
   extensions.fsmonitor= (fsmonitor !)
   format.exp-rc-dirstate-v2=1 (dirstate-v2 !)
   largefiles.usercache=$TESTTMP/.cache/largefiles
   lfs.usercache=$TESTTMP/.cache/lfs
   ui.slash=True
   ui.interactive=False
   ui.detailed-exit-code=True
   ui.merge=internal:merge
   ui.mergemarkers=detailed
   ui.promptecho=True
   ui.ssh=* (glob)
   ui.timeout.warn=15
   web.address=localhost
   web\.ipv6=(?:True|False) (re)
   web.server-header=testing stub value
 #endif
 
   $ hg init t
   $ cd t
 
 Prepare a changeset:
 
   $ echo a > a
   $ hg add a
 
   $ hg status
   A a
 
 Writes to stdio succeed and fail appropriately
 
 #if devfull
   $ hg status 2>/dev/full
   A a
 
   $ hg status >/dev/full
   abort: No space left on device
   [255]
 #endif
 
 #if devfull
   $ hg status >/dev/full 2>&1
   [255]
 
   $ hg status ENOENT 2>/dev/full
   [255]
 #endif
 
 On Python 3, stdio may be None:
 
   $ hg debuguiprompt --config ui.interactive=true 0<&-
-   abort: Bad file descriptor
+   abort: Bad file descriptor (no-rhg !)
+   abort: response expected (rhg !)
   [255]
   $ hg version -q 0<&-
   Mercurial Distributed SCM * (glob)
 
-#if py3
+#if py3 no-rhg
   $ hg version -q 1>&-
   abort: Bad file descriptor
   [255]
 #else
   $ hg version -q 1>&-
 #endif
   $ hg unknown -q 1>&-
   hg: unknown command 'unknown'
   (did you mean debugknown?)
   [10]
 
   $ hg version -q 2>&-
   Mercurial Distributed SCM * (glob)
   $ hg unknown -q 2>&-
   [10]
 
   $ hg commit -m test
 
 This command is ancient:
 
   $ hg history
   changeset:   0:acb14030fe0a
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     test
   
 
 Verify that updating to revision 0 via commands.update() works properly
 
   $ cat <<EOF > update_to_rev0.py
   > from mercurial import commands, hg, ui as uimod
   > myui = uimod.ui.load()
   > repo = hg.repository(myui, path=b'.')
   > commands.update(myui, repo, rev=b"0")
   > EOF
   $ hg up null
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ "$PYTHON" ./update_to_rev0.py
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg identify -n
   0
 
 
 Poke around at hashes:
 
   $ hg manifest --debug
   b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 644   a
 
   $ hg cat a
   a
 
 Verify should succeed:
 
   $ hg verify
   checking changesets
   checking manifests
   crosschecking files in changesets and manifests
   checking files
   checked 1 changesets with 1 changes to 1 files
 
 Repository root:
 
   $ hg root
   $TESTTMP/t
   $ hg log -l1 -T '{reporoot}\n'
   $TESTTMP/t
   $ hg root -Tjson | sed 's|\\\\|\\|g'
   [
    {
     "hgpath": "$TESTTMP/t/.hg",
     "reporoot": "$TESTTMP/t",
     "storepath": "$TESTTMP/t/.hg/store"
    }
   ]
 
 At the end...
 
   $ cd ..
 
 Status message redirection:
 
   $ hg init empty
 
  status messages are sent to stdout by default:
 
   $ hg outgoing -R t empty -Tjson 2>/dev/null
   comparing with empty
   searching for changes
   [
    {
     "bookmarks": [],
     "branch": "default",
     "date": [0, 0],
     "desc": "test",
     "node": "acb14030fe0a21b60322c440ad2d20cf7685a376",
     "parents": ["0000000000000000000000000000000000000000"],
     "phase": "draft",
     "rev": 0,
     "tags": ["tip"],
     "user": "test"
    }
   ]
 
  which can be configured to send to stderr, so the output wouldn't be
  interleaved:
 
   $ cat <<'EOF' >> "$HGRCPATH"
   > [ui]
   > message-output = stderr
   > EOF
   $ hg outgoing -R t empty -Tjson 2>/dev/null
   [
    {
     "bookmarks": [],
     "branch": "default",
     "date": [0, 0],
     "desc": "test",
     "node": "acb14030fe0a21b60322c440ad2d20cf7685a376",
     "parents": ["0000000000000000000000000000000000000000"],
     "phase": "draft",
     "rev": 0,
     "tags": ["tip"],
     "user": "test"
    }
   ]
   $ hg outgoing -R t empty -Tjson >/dev/null
   comparing with empty
   searching for changes
 
  this option should be turned off by HGPLAIN= since it may break scripting use:
 
   $ HGPLAIN= hg outgoing -R t empty -Tjson 2>/dev/null
   comparing with empty
   searching for changes
   [
    {
     "bookmarks": [],
     "branch": "default",
     "date": [0, 0],
     "desc": "test",
     "node": "acb14030fe0a21b60322c440ad2d20cf7685a376",
     "parents": ["0000000000000000000000000000000000000000"],
     "phase": "draft",
     "rev": 0,
     "tags": ["tip"],
     "user": "test"
    }
   ]
 
  but still overridden by --config:
 
   $ HGPLAIN= hg outgoing -R t empty -Tjson --config ui.message-output=stderr \
   > 2>/dev/null
   [
    {
     "bookmarks": [],
     "branch": "default",
     "date": [0, 0],
     "desc": "test",
     "node": "acb14030fe0a21b60322c440ad2d20cf7685a376",
     "parents": ["0000000000000000000000000000000000000000"],
     "phase": "draft",
     "rev": 0,
     "tags": ["tip"],
     "user": "test"
    }
   ]
 
 Invalid ui.message-output option:
 
   $ hg log -R t --config ui.message-output=bad
   abort: invalid ui.message-output destination: bad
   [255]
 
 Underlying message streams should be updated when ui.fout/ferr are set:
 
   $ cat <<'EOF' > capui.py
   > from mercurial import pycompat, registrar
   > cmdtable = {}
   > command = registrar.command(cmdtable)
   > @command(b'capui', norepo=True)
   > def capui(ui):
   >     out = ui.fout
   >     ui.fout = pycompat.bytesio()
   >     ui.status(b'status\n')
   >     ui.ferr = pycompat.bytesio()
   >     ui.warn(b'warn\n')
   >     out.write(b'stdout: %s' % ui.fout.getvalue())
   >     out.write(b'stderr: %s' % ui.ferr.getvalue())
   > EOF
   $ hg --config extensions.capui=capui.py --config ui.message-output=stdio capui
   stdout: status
   stderr: warn