Re: [PATCH] Use meson's detected python installation

[Peter Maydell <peter.maydell@linaro.org>]

On Fri, 5 Sept 2025 at 08:26, Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> On 9/4/25 17:11, Peter Foley wrote:
> > Relying on `python3` to be avilable in $PATH doesn't work in some build
> > environments. Update the build files to use the found python binary
> > explicitly.
>
> Meson already does this, if the file is not executable.  See
> docs/devel/build-system.rst:
>
>    Meson has a special convention for invoking Python scripts: if their
>    first line is ``#! /usr/bin/env python3`` and the file is *not*
>    executable, find_program() arranges to invoke the script under the
>    same Python interpreter that was used to invoke Meson.  This is the
>    most common and preferred way to invoke support scripts from Meson
>    build files, because it automatically uses the value of configure's
>    --python= option.
>
> Using "[python, 'foo']" is only needed for scripts "where it is
> desirable to make the script executable (for example for test scripts
> that developers may want to invoke from the command line, such as
> tests/qapi-schema/test-qapi.py)".

Wow, this seems like a super fragile way to do things. My
natural expectation would be that scripts generally would
be executable. If we accidentally make a script executable
that meson is invoking without explicit [python, ...]
then everything continues to work for almost everybody,
except in this corner case where the 'python3' on the path
is sufficiently wrong to not work: so we're likely to not
notice the mistake for ages.

-- PMM