pyproject.toml should be included in sdist by default

[pganssle]

An issue came up at work recently where installing python-daemon with pip was hitting the easy_install path. I assumed it was because python-daemon didn't have a pyproject.toml, but it turns out they do - it's just not included in the Manifest.in, so it didn't get included in the sdist. To verify this I created a super basic example project and it does seem that the default is to exclude pyproject.toml.

Given that pyproject.toml is one of the most important files to have when executing a build, it should be included in the sdist unless explicitly excluded.

[daa]

I think the same issue should be put into Python bugtracker for distutils to include pyproject.toml by default.

[pganssle]

@daa I think at this point new changes like this are not likely to be accepted in distutils, but you are welcome to open an issue. Generally the guidance is to use setuptools.

[uranusjr]

From PEP 517:

build_sdist

[…] A .tar.gz source distribution (sdist) contains a single top-level directory […]. This directory must also contain the pyproject.toml from the build directory, and a PKG-INFO file containing metadata in the format described in PEP 345.

So at least sdists built through build_meta must contain pyproject.toml. It is still debatable whether setup.py sdist (which is not restricted by PEP 517) should do this by default though.

Should I file a PR to special-case build_meta.build_sdist? As it stands Setuptools is not technically compliant to PEP 517. (Edit: I already did.)