add meson_python to PYTHON_TOOLCHAIN

[dimpase]

fix race condition for building scipy, possibly other meson_python deps

cf e.g. sage-dev report

[mkoeppe]

No, that's not needed (and does not fix it). I've fixed it already in #36276.

[dimpase]

I don't get it it. It has nothing to do with spkg-configure stuff, and anyway I don't see how it's fixed. Are you saying meson_python does not belong to PYTHON_TOOLCHAIN? If not, one still needs it ready for e.g. scipy.

[mkoeppe]

It has nothing to do with spkg-configure stuff, and anyway I don't see how it's fixed.

There was a bug that caused meson_python to be recognized as a system-provided package.
For such packages, build/make/Makefile will have meson_python in DUMMY_PACKAGES, and thus the dependency on meson_python is rewritten as a dependency on the .dummy file.

[dimpase]

I don't get it it. It has nothing to do with spkg-configure stuff, and anyway I don't see how it's fixed. Are you saying meson_python does not belong to PYTHON_TOOLCHAIN? If not, one still needs it ready for e.g. scipy.

I'd even say that #36276 is already overfull with not directly related issues, so have this fixed there isn't very transparent, and has to be explicitly mentioned - if it's indeed the case.

[mkoeppe]

Read the PR description -- it's already there.

[dimpase]

I don't understand. meson_python may or may not be a system package, How is it in this regard different to other packages in PYTHON_TOOLCHAIN ?

[dimpase]

Read the PR description -- it's already there.

Where? There is nothing on it in #36276 (comment)

[mkoeppe]

"Fixes https://groups.google.com/g/sage-release/c/1wOBmhvNJqc/m/Jk14VAbjBAAJ (hence marked critical)"

[mkoeppe]

Do you see it?

[mkoeppe]

Are you saying meson_python does not belong to PYTHON_TOOLCHAIN?

Yes, it does not belong there because most Python packages don't need it.

[mkoeppe]

I don't understand. meson_python may or may not be a system package

The bug was that it was marked as a package available from the system when it wasn't.

[github-actions]

Documentation preview for this PR (built with commit 6412e93; changes) is ready! 🎉