Add support for packaging type stubs in pure Rust project layout

[messense]

Closes #553

[ravenexp]

PEP 561 requires py.typed marker file to be added to packages containing .pyi stubs:

https://www.python.org/dev/peps/pep-0561/#packaging-type-information

[messense]

PEP 561 requires py.typed marker file to be added to packages containing .pyi stubs:

https://www.python.org/dev/peps/pep-0561/#packaging-type-information

Thanks! Totally forgot about that...

[ravenexp]

I've tried to build my Rust-only extension using this patch, and the embedded type information stub was discovered by both mypy and PyCharm. Everything works as expected.

Maybe an info message for the user could be added, signalling that the type information stub was discovered and included in the distribution. Currently, when I add a magically-named file to the project root directory, I can only hope that I did everything correctly, and there is no way to verify the result except for manually inspecting the built wheel contents.

[messense]

Maybe an info message for the user could be added, signalling that the type information stub was discovered and included in the distribution. Currently, when I add a magically-named file to the project root directory, I can only hope that I did everything correctly, and there is no way to verify the result except for manually inspecting the built wheel contents.

Good idea, added.

🔗 Found pyo3 bindings with abi3 support for Python ≥ 3.6
🐍 Not using a specific python interpreter (With abi3, an interpreter is only required on windows)
    Finished dev [unoptimized + debuginfo] target(s) in 0.02s
📖 Found type stub file at pyo3_pure.pyi
📦 Built wheel for abi3 Python ≥ 3.6 to dist/pyo3_pure-2.1.2-cp36-abi3-macosx_11_0_arm64.whl