.. Copyright 2013-2022 Lawrence Livermore National Security, LLC and other
Spack Project Developers. See the top-level COPYRIGHT file for details.
SPDX-License-Identifier: (Apache-2.0 OR MIT)
.. _mesonpackage:
------------
MesonPackage
------------
Much like Autotools and CMake, Meson is a build system. But it is
meant to be both fast and as user friendly as possible. GNOME's goal
is to port modules to use the Meson build system.
^^^^^^
Phases
^^^^^^
The ``MesonPackage`` base class comes with the following phases:
#. ``meson`` - generate ninja files
#. ``build`` - build the project
#. ``install`` - install the project
By default, these phases run:
.. code-block:: console
$ mkdir spack-build
$ cd spack-build
$ meson .. --prefix=/path/to/installation/prefix
$ ninja
$ ninja test # optional
$ ninja install
Any of these phases can be overridden in your package as necessary.
There is also a ``check`` method that looks for a ``test`` target
in the build file. If a ``test`` target exists and the user runs:
.. code-block:: console
$ spack install --test=root <meson-package>
Spack will run ``ninja test`` after the build phase.
^^^^^^^^^^^^^^^
Important files
^^^^^^^^^^^^^^^
Packages that use the Meson build system can be identified by the
presence of a ``meson.build`` file. This file declares things
like build instructions and dependencies.
One thing to look for is the ``meson_version`` key that gets passed
to the ``project`` function:
.. code-block:: none
:emphasize-lines: 10
project('gtk+', 'c',
version: '3.94.0',
default_options: [
'buildtype=debugoptimized',
'warning_level=1',
# We only need c99, but glib needs GNU-specific features
# https://github.com/mesonbuild/meson/issues/2289
'c_std=gnu99',
],
meson_version: '>= 0.43.0',
license: 'LGPLv2.1+')
This means that Meson 0.43.0 is the earliest release that will work.
You should specify this in a ``depends_on`` statement.
^^^^^^^^^^^^^^^^^^^^^^^^^
Build system dependencies
^^^^^^^^^^^^^^^^^^^^^^^^^
At the bare minimum, packages that use the Meson build system need
``meson`` and ```ninja``` dependencies. Since this is always the case,
the ``MesonPackage`` base class already contains:
.. code-block:: python
depends_on('meson', type='build')
depends_on('ninja', type='build')
If you need to specify a particular version requirement, you can
override this in your package:
.. code-block:: python
depends_on('meson@0.43.0:', type='build')
depends_on('ninja', type='build')
^^^^^^^^^^^^^^^^^^^
Finding meson flags
^^^^^^^^^^^^^^^^^^^
To get a list of valid flags that can be passed to ``meson``, run the
following command in the directory that contains ``meson.build``:
.. code-block:: console
$ meson setup --help
^^^^^^^^^^^^^^^^^^^^^^^^^^
Passing arguments to meson
^^^^^^^^^^^^^^^^^^^^^^^^^^
If you need to pass any arguments to the ``meson`` call, you can
override the ``meson_args`` method like so:
.. code-block:: python
def meson_args(self):
return ['--warnlevel=3']
This method can be used to pass flags as well as variables.
Note that the ``MesonPackage`` base class already defines variants for
``buildtype``, ``default_library`` and ``strip``, which are mapped to default
Meson arguments, meaning that you don't have to specify these.
^^^^^^^^^^^^^^^^^^^^^^
External documentation
^^^^^^^^^^^^^^^^^^^^^^
For more information on the Meson build system, see:
https://mesonbuild.com/index.html
