gh-157384: Set package context in PyImport_CreateModuleFromInitfunc()

[itamaro]

A single-phase init function that creates its module using only the last component of a dotted name (as pybind11 does for submodules) got a module whose name was the short name. Set the package context while calling the init function, as the dynamic loader does, so the module gets the full name from the spec.

AI assisted with Claude Fable 5.1

• Issue: PyImport_CreateModuleFromInitfunc(): wrong __name__ for submodules, non-ASCII names rejected, inittab name clashes #157384

[read-the-docs-community]

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📚 cpython-previews | 🛠️ Build #34530612 | 📁 Comparing 238cdb7 against main (2cd6d4b)

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2 files changed

± c-api/import.html
± whatsnew/changelog.html

[encukou]

Would it be possible to fix the binding generator instead?

[itamaro]

Would it be possible to fix the binding generator instead?

In what way?

afaik pybind11 3+ already defaults to multi-phase init, so this issue is mostly with older pybind11 extensions (2.13 and older), or hand-written C extensions.

this fix makes this API honor the documented cpython contract for single-phase init extensions.