Re: [RFC PATCH 3/3] configure: install meson to a python virtual environment

[Paolo Bonzini <pbonzini@redhat.com>]

On 3/28/23 23:11, John Snow wrote:
> +        # Is it a problem if we front-load this now and run it again later?

I would just move all the "pip install" bits after configure has called 
out to git-submodule.sh.

> +    # --no-build-isolation was added to pip 10.0.
> +    # --no-use-pep517 was added ... sometime after 18.1?
> +    pip_flags='--no-build-isolation'
> +    if $python -m pip install --help | grep 'no-use-pep517' > /dev/null 2>&1 ; then
> +        pip_flags="${pip_flags} --no-use-pep517"
> +    fi
> +    if ! pip_install $pip_flags "${source_path}/meson" ; then
> +        exit 1
>       fi
>   fi

Hmm, I'm not a huge fan of using this flag to cover (essentially) an 
implementation detail of pip.  I would really keep on using either 
meson.py here, though I appreciate that this patch is effective in 
showing off the venv concept, without getting into downloading packages 
and adding flags to the configure script.

> 
> +# Smoke tests: these shouldn't fail, but I have little faith in esoteric
> +# platforms I've never used to not do something Deep Strange when I am
> +# not looking.
> +if ! test -e "$meson" ; then
> +    error_exit "??? pyvenv/bin/meson not found, somehow ???"
> +fi
> +echo "Meson $($meson --version) found: $meson"
> +if ! version_ge "$($meson --version)" 0.61.5; then
> +    error_exit "??? Meson version is too old ???"
> +fi

I think this can go away in the final version, since the version is 
checked against the project() invocation of meson.build.

Paolo