Inline dependency-versions syntax

[joerick]

To help with #2002, I propose a way to specify dependency version constraints inline, without the extra file. This would eliminate the need for an additional CIBW_PYODIDE_BUILD_VERSION option, while being consistent with our existing version management system.

This would allow setting the pyodide-build version like:

CIBW_DEPENDENCY_VERSIONS_PYODIDE: "packages: pyodide-build==0.29.1"

So far, no implementation yet, just docs for discussion.

[joerick]

Having reviewed #2002 again, I think this would be a useful feature. Specifically, there's a check for compatible versions between pyodide and pyodide-build - if we provide an option for CIBW_PYODIDE_VERSION, and we don't have this, changing pyodide version becomes a bit hassle, because you need to make a constraints file as well.

[joerick]

This should be ready to go, pending review.

[henryiii]

Two questions:

• packages = [] would avoid pinning?
• How does this interact with inherit? Can you inherit from a file and add a package?

[henryiii]

I've managed to make some conflicts due to #2276. I can rebase if you prefer, sorry!

[joerick]

• packages = [] would avoid pinning?

Good point. I think that should be equivalent to 'latest', as in it pins nothing. I'll make sure that's covered with a test case.

• How does this interact with inherit? Can you inherit from a file and add a package?

It doesn't inherit. I considered including it but because of the backwards-compatibility requirements¹ it's awkward to implement (the syntax is different from the other table-style options). Also, I couldn't think of a situation it might be useful. What do you think?

Footnotes

1. the existing string-form (just a path) means that if we start using the table-form, characters like ;: will be parsed differently. I'm sure it could be worked around somehow, but it might require some messy code, didn't seem worth the effort/complexity. ↩