Flit can't generate a proper wheel file name for project names with dots

[Jackenmen]

For example:

• pyproject.toml

[build-system]
requires = ["flit_core >=2,<4"]
build-backend = "flit_core.buildapi"

[tool.flit.metadata]
module = "simplepackage"
dist-name = "simplepackage.py"
author = "Jakub Kuczys"
classifiers = [ "License :: OSI Approved :: MIT License",]

• simplepackage/__init__.py

"""Description..."""

__version__ = "1.0.0"

Running flit build causes this output

Writing generated setup.py                                I-flit.sdist
Built sdist: dist\simplepackage.py-1.0.0.tar.gz      I-flit_core.sdist
Copying package file(s) from C:\Users\Jakub\AppData\Local\Temp\tmpsvq3ymrp\simplepackage.py-1.0.0\simplepackage  I-flit_core.wheel
Writing metadata files                               I-flit_core.wheel
Writing the record of files                          I-flit_core.wheel
Built wheel: dist\simplepackage_py-1.0.0-py2.py3-none-any.whl  I-flit_core.wheel

and these files to be generated:

simplepackage.py-1.0.0.tar.gz
simplepackage_py-1.0.0-py2.py3-none-any.whl

While for it to work properly, it should generate these files instead:

simplepackage.py-1.0.0.tar.gz
simplepackage.py-1.0.0-py2.py3-none-any.whl

[takluyver]

I think the underscore is correct. The relevant part of the wheel spec says:

In distribution names, any run of -_. characters (HYPHEN-MINUS, LOW LINE and FULL STOP) should be replaced with _ (LOW LINE). This is equivalent to PEP 503 normalisation followed by replacing - with _.

[Jackenmen]

When trying to upload to PyPI, I run into this:
https://github.com/pypa/warehouse/blob/442148581c61163a2c30bca25f8ef3f06457e932/warehouse/forklift/legacy.py#L1190-L1197

As can be seen here, dots are not included in the replaced characters:
https://github.com/pypa/setuptools/blob/47b724639703d0c512f275a316dbb99e6c226e38/pkg_resources/__init__.py#L1304-L1309

Not sure whether this is because the wheel spec is wrong or because the implementation in pkg_resources is wrong but currently this prevents projects with dots in names from using wheels built by flit (though perhaps manual file rename before upload would be enough as a workaround, not sure whether this affects anything other than the file name).

[uranusjr]

The underscore is correct. This should be fixed in warehouse.

[takluyver]

We did have to change the wheel spec around filenames fairly recently (see pypa/pip#9628) - we found one of those cases where the spec had diverged from what important tools actually do, and adjusting the spec seemed like the most practical way forwards. But it's not a big surprise that what was written in the spec before got implemented in some places.

It looks like this has been accepted as a bug in Warehouse, so I'll close the issue here. Comments will still be available for follow up if needed.