namespaced packages ignored/mis-named

[H-Plus-Time]

Bug Description

PEP 420-style namespace packages like the following:

foo_a/
  Cargo.toml
  python/foo/a/
    __init__.py
  pyproject.toml
  src/
    lib.rs
foo_b/
  Cargo.toml
  python/foo/b/
    __init__.py
  pyproject.toml
  src/
    lib.rs

are skipped entirely in find_spec (because they appear as if they are not top-level packages, since importlib.util.find_spec passes a specialized _NamespacePath to find_spec).

Flagging on enable_automatic_installation appears to work, but actually just installs the namespaced package as foo (resulting in silent clobbering of members of the namespace).

I should have a PR soon-ish for this.

Steps to Reproduce

1. Initialize a boilerplate folder structure along the lines described above, marking python-source = "python", module-name = "foo.._rustin the Cargo.tomls and insertingfrom . import _rust`.
2. install the hook and import from a venv with the namespace members editable-installed.
3. Modify any of the files - observe the hook missing them.

Please provide the output of python -m maturin_import_hook version (or provide manually)

OS: Linux-6.12.4-arch1-1-x86_64-with-glibc2.40
Python: CPython 3.12.8
maturin-import-hook: 0.2.0
maturin: maturin 1.7.8
rustc: rustc 1.81.0 (eeb90cda1 2024-09-04)
pip: ?

Does maturin develop work when run manually for your project?

• Yes/No (leave blank if not applicable)

[H-Plus-Time]

A few repositories where this happens:

• https://github.com/kylebarron/arro3
• https://github.com/geoarrow/geoarrow-rs/tree/main/python

Quite possible this is only in mixed python/rust projects, and reproducible in both src-layout and flat-layout packages.