add build-backend to pyproject.toml

[Alessandro-Barbieri]

Could you add add build-backend to pyproject.toml?

[benkiel]

More detail (why do you want this, what will it add, etc) and possibly a PR?

[alerque]

I believe it's required for PEP 517 tooling and would avoid downstream packagers from having to hack in the info manually.

[Alessandro-Barbieri]

I need it to move the ebuild of fontparts in the gentoo overlay ::guru to use PEP517
see https://projects.gentoo.org/python/guide/distutils.html#the-pep-517-and-legacy-modes

[benkiel]

Got it. Read that doc, very helpful: do you know which build-background we should be using? Ok if not, I'll sort it out if not.

[justvanrossum]

Probably setuptools, as that's what setup.py uses.

[benkiel]

@justvanrossum that's my guess to. On figuring it out as we do use setuptools_scm which has wrinkles it seems.

[justvanrossum]

Perhaps go pyproject.toml all the way, and only leave a stub setup.py. I'm doing that with a new project and seems to work ok, including setuptools_scm.

[justvanrossum]

My build-system section looks like this:

[build-system]
requires = ["setuptools", "setuptools-scm[toml]"]
build-backend = "setuptools.build_meta"