view rust/hgcli/README.md @ 45375:8c466bcb0879

revert: remove dangerous `parents` argument from `cmdutil.revert()`

As we found out the hard way (thanks to spectral@ for figuring it
out!), `cmdutil.revert()`'s `parents` argument must be
`repo.dirstate.parents()` or things may go wrong. We had an extension
that passed in the target commit as the first parent. The `hg split`
command from the evolve extension seems to have made the same mistake,
but I haven't looked carefully.

The problem is that `cmdutil._performrevert()` calls
`dirstate.normal()` on reverted files if the commit to revert to
equals the first parent. So if you pass in `ctx=foo` and
`parents=(foo.node(), nullid)`, then `dirstate.normal()` will be
called for the revert files, even though they might not be clean in
the working copy.

There doesn't seem to be any reason, other than a tiny performance
benefit, to passing the `parents` around instead of looking them up
again in `cmdutil._performrevert()`, so that's what this patch does.

Differential Revision: https://phab.mercurial-scm.org/D8925

# Oxidized Mercurial

This project provides a Rust implementation of the Mercurial (`hg`)
version control tool.

Under the hood, the project uses
[PyOxidizer](https://github.com/indygreg/PyOxidizer) to embed a Python
interpreter in a binary built with Rust. At run-time, the Rust `fn main()`
is called and Rust code handles initial process startup. An in-process
Python interpreter is started (if needed) to provide additional
functionality.

# Building

This project currently requires an unreleased version of PyOxidizer
(0.7.0-pre). For best results, build the exact PyOxidizer commit
as defined in the `pyoxidizer.bzl` file:

    $ git clone https://github.com/indygreg/PyOxidizer.git
    $ cd PyOxidizer
    $ git checkout <Git commit from pyoxidizer.bzl>
    $ cargo build --release

Then build this Rust project using the built `pyoxidizer` executable::

    $ /path/to/pyoxidizer/target/release/pyoxidizer build

If all goes according to plan, there should be an assembled application
under `build/<arch>/debug/app/` with an `hg` executable:

    $ build/x86_64-unknown-linux-gnu/debug/app/hg version
    Mercurial Distributed SCM (version 5.3.1+433-f99cd77d53dc+20200331)
    (see https://mercurial-scm.org for more information)

    Copyright (C) 2005-2020 Matt Mackall and others
    This is free software; see the source for copying conditions. There is NO
    warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

# Running Tests

To run tests with a built `hg` executable, you can use the `--with-hg`
argument to `run-tests.py`. But there's a wrinkle: many tests run custom
Python scripts that need to `import` modules provided by Mercurial. Since
these modules are embedded in the produced `hg` executable, a regular
Python interpreter can't access them! To work around this, set `PYTHONPATH`
to the Mercurial source directory. e.g.:

    $ cd /path/to/hg/src/tests
    $ PYTHONPATH=`pwd`/.. python3.7 run-tests.py \
        --with-hg `pwd`/../rust/hgcli/build/x86_64-unknown-linux-gnu/debug/app/hg