[FR] support pep-621 - storing core project metadata in pyproject.toml

[RonnyPfannschmidt]

What's the problem this feature will solve?

this is intended to build on #1688

with PEP-621 python packaging has been extended with a standard to include core metadata in pyproject.toml

Describe the solution you'd like

in order for setuptools to support it i beleive i see the need for the following steps

• basic toml support in setuptools (just mirroring setup.cfg in pyproject.toml, as setup.cfg is still a supoerset of that the peps support
• a loader for pep-621 meta-data (ideally via packaging)
• [FR] Allow plugins to pull in configuration from pyproject.toml #3415
• warnings for usages of tool.setuptools when core package metadata is viable (maybe via jsonschema + its deprecation mechanism)

Alternative Solutions

No response

Additional context

Support incremental complexity and build steps for packages

Code of Conduct

• I agree to follow the PSF Code of Conduct

[abravalheri]

Hi @RonnyPfannschmidt, I was just wondering if you could clarify a bit more the requirement:

warnings for usages of tool.setuptools when core package metadata is viable (maybe via jsonschema + its deprecation mechanism)

I have been working on a tool to assist the migration once PEP621 is adopted by setuptools, but since not all information in setup.cfg is covered by the PEP, I kind of assumed a tool.setuptools table is required in the TOML file... (the assumption is only provisional, and subject to change once we have a clearer idea on how to encode those extra fields).

Does the requirement you wrote mean that tool.setuptools should not be used?

[RonnyPfannschmidt]

@abravalheri if people put Metadata that has a location as per the pep into the tool. Setuptools table instead, there should be a warning /error

The table is absolutely needed as setup.cfg is a superset of the Metadata the pep directly in cooperates

[abravalheri]

Thank you very much for the clarification @RonnyPfannschmidt.