rust: move rustfmt.toml to repo root so it can be used by `hg fix`
`hg fix` runs the formatters from the repo root so it doesn't pick up
the `rustfmt.toml` configs we had in each the `hg-core`, `hg-cpython`,
and `rhg` packages, which resulted in warnings about `async fn` not
existing in Rust 2015. This patch moves the `rustfmt.toml` file to the
root so `hg fix` will use it.
By putting the `rustfmt.toml` file in a higher-level directory, it
also applies to the `chg` and `hgcli` packages. That makes
`test-check-rust-format.t` fail, so this patch also applies the new
formatting rules to those packages.
Differential Revision: https://phab.mercurial-scm.org/D9142
# 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