packaging: avoid running bare "make install" in debian/rules
We change the "override_dh_install" target to "override_dh_auto_install"
in debian/rules (see dh_auto_install(1) for details). This is because we
do not want "make install" to be run automatically as we need the
--install-layout=deb of "setup.py install". Otherwise, files end up in
$DESTDIR/usr/local. At the moment, this is not a problem since files
installed in debian/tmp (the default location) are not packed into
binary packages (because there are debian/mercurial and
debian/mercurial-common directories). This is cleaner to avoid running
make more than needed.
===================
Mercurial Rust Code
===================
This directory contains various Rust code for the Mercurial project.
The top-level ``Cargo.toml`` file defines a workspace containing
all primary Mercurial crates.
Building
========
To build the Rust components::
$ cargo build
If you prefer a non-debug / release configuration::
$ cargo build --release
Features
--------
The following Cargo features are available:
localdev (default)
Produce files that work with an in-source-tree build.
In this mode, the build finds and uses a ``python2.7`` binary from
``PATH``. The ``hg`` binary assumes it runs from ``rust/target/<target>hg``
and it finds Mercurial files at ``dirname($0)/../../../``.
Build Mechanism
---------------
The produced ``hg`` binary is *bound* to a CPython installation. The
binary links against and loads a CPython library that is discovered
at build time (by a ``build.rs`` Cargo build script). The Python
standard library defined by this CPython installation is also used.
Finding the appropriate CPython installation to use is done by
the ``python27-sys`` crate's ``build.rs``. Its search order is::
1. ``PYTHON_SYS_EXECUTABLE`` environment variable.
2. ``python`` executable on ``PATH``
3. ``python2`` executable on ``PATH``
4. ``python2.7`` executable on ``PATH``
Additional verification of the found Python will be performed by our
``build.rs`` to ensure it meets Mercurial's requirements.
Details about the build-time configured Python are built into the
produced ``hg`` binary. This means that a built ``hg`` binary is only
suitable for a specific, well-defined role. These roles are controlled
by Cargo features (see above).
Running
=======
The ``hgcli`` crate produces an ``hg`` binary. You can run this binary
via ``cargo run``::
$ cargo run --manifest-path hgcli/Cargo.toml
Or directly::
$ target/debug/hg
$ target/release/hg
You can also run the test harness with this binary::
$ ./run-tests.py --with-hg ../rust/target/debug/hg
.. note::
Integration with the test harness is still preliminary. Remember to
``cargo build`` after changes because the test harness doesn't yet
automatically build Rust code.