Re: [PATCH v3 5/6] meson: prefer 'sphinx-build' to 'sphinx-build-3'

[Paolo Bonzini <pbonzini@redhat.com>]

On 2/21/23 12:31, Paolo Bonzini wrote:
> On 2/21/23 02:24, John Snow wrote:
>> Once upon a time, "sphinx-build" on certain RPM platforms invoked
>> specifically a Python 2.x version, while "sphinx-build-3" was a distro
>> shim for the Python 3.x version.
>>
>> These days, none of our supported platforms utilize a 2.x version, so it
>> should be safe to search for 'sphinx-build' prior to 'sphinx-build-3',
>> which will prefer pip/venv installed versions of sphinx if they're
>> available.
>>
>> This adds an extremely convenient ability to test document building
>> ability in QEMU across multiple versions of Sphinx for the purposes of
>> compatibility testing.
> 
> Can we just use "$PYTHON -m sphinx.cmd.build" instead, to ensure that we 
> don't
> escape the virtual environment?  Or even better, we could have a simple 
> script
> like this:
> 
> #! /usr/bin/env python3
> 
> from pkg_resources import load_entry_point
> 
> if __name__ == '__main__':
>      if sys.argv[1] == '--check':
>          try:
>              load_entry_point(sys.argv[2], 'console_scripts', sys.argv[3])
>              sys.exit(0)
>          except ImportError:
>              sys.exit(1)
>      else:
>          entry_point = load_entry_point(sys.argv[1], 'console_scripts', 
> sys.argv[2])
>          # The second argument to python-run.py becomes sys.argv[0]
>          del sys.argv[0:1]
>          sys.exit(entry_point())
> 
> then docs/meson.build can do this:
> 
> python_run = find_program('scripts/python-run.py')
> build_docs = false
> if get_feature('docs') \
>    .require(run_command(python_run, '--check', 'sphinx', 'sphinx-build',
>                         check: false).returncode() == 0,
>             error: 'Could not find sphinx installation') \
>    .allowed()
>    # The sphinx module is installed
>    SPHINX_ARGS = ['env', 'CONFDIR=' + qemu_confdir,
>                   python_run, 'sphinx', 'sphinx-build', '-q']
>    ...
>    build_docs = (sphinx_build_test_out.returncode() == 0)
>    ...
> endif
> 
> This again ensures that sphinx-build will not escape the virtual 
> environment
> if there is one.  configure can also use the script to run meson, though 
> that
> can come later.

Ok, it's a bit harder but it works.  Patch coming later today.

Paolo