view rust/hgcli/README.md @ 44764:92627c42e7c2 stable

packaging: isolate invocation of WiX to own function

Like we did for Inno, we want to split out the building
of Mercurial from invoking the packaging tool so that we
can introduce an alternate build mechanism.

As part of this refactor, there are inconsequential changes
to file layouts. Before, some shared files such as the
WiX binaries and merge modules would be installed under
build/. Now, they are installed under build/wix-*. This
is to keep implementation simpler. But it also helps keep
build state more isolated.

Differential Revision: https://phab.mercurial-scm.org/D8474

# 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