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

[Markus Armbruster <armbru@redhat.com>]

John Snow <jsnow@redhat.com> writes:

> On Wed, Feb 22, 2023 at 2:15 AM Markus Armbruster <armbru@redhat.com> wrote:
>>
>> John Snow <jsnow@redhat.com> writes:
>>
>> > On Tue, Feb 21, 2023, 1:50 AM Markus Armbruster <armbru@redhat.com> wrote:
>> >
>> >> John Snow <jsnow@redhat.com> writes:
>> >>
>> >> > 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.
>> >> >
>> >> > Signed-off-by: John Snow <jsnow@redhat.com>
>> >> > ---
>> >> >  docs/meson.build | 2 +-
>> >> >  1 file changed, 1 insertion(+), 1 deletion(-)
>> >> >
>> >> > diff --git a/docs/meson.build b/docs/meson.build
>> >> > index 9136fed3b73..906034f9a87 100644
>> >> > --- a/docs/meson.build
>> >> > +++ b/docs/meson.build
>> >> > @@ -1,5 +1,5 @@
>> >> >  if get_option('sphinx_build') == ''
>> >> > -  sphinx_build = find_program(['sphinx-build-3', 'sphinx-build'],
>> >> > +  sphinx_build = find_program(['sphinx-build', 'sphinx-build-3'],
>> >> >                                required: get_option('docs'))
>> >> >  else
>> >> >    sphinx_build = find_program(get_option('sphinx_build'),
>> >>
>> >> Do we still need to check for sphinx-build-3?  Or asked differently, is
>> >> there any supported build host that provides only sphinx-build-3?
>> >>
>> >
>> > Yes, modern Fedora still uses "sphinx-build-3" as the name in /usr/bin for
>> > the rpm-packaged version of sphinx.
>>
>> For what it's worth, python3-sphinx-5.0.2-2.fc37.noarch provides
>>
>>     /usr/bin/sphinx-build
>>     /usr/bin/sphinx-build-3
>>     /usr/bin/sphinx-build-3.11
>>
>> where the latter two are symbolic links to the first.  No need to check
>> for sphinx-build-3 here.
>
> Oh, I see. I guess it should be fine, but only if we explicitly drop
> support for the 3.6 version that comes with CentOS. I'm not entirely
> sure if "sphinx-build-3" is used anywhere else, I *think* it's just an
> rpm-ism.

I can see just two reasons for trying sphinx-build-3:

1. sphinx-build does not exist.

2. sphinx-build exists, but uses Python 2, which doesn't work with our
   Sphinx extension.

The commit message seems to claim it's not 2.

So, what is it?