Unclear what the build system is

[mgorny]

What is the actual build system used by mutagen?

pyproject.toml has some poetry metadata but the build-system section includes setuptools requirements. However, even then it doesn't declare any build-backend, neither setuptools' nor poetry's.

[lazka]

https://peps.python.org/pep-0517/

If the pyproject.toml file is absent, or the build-backend key is missing, the source tree is not using this specification, and tools should revert to the legacy behaviour of running setup.py (either directly, or by implicitly invoking the setuptools.build_meta:legacy backend).

Is this causing any problems (both "build" and "pip" seem to do the right thing) ? I can make it explicit if needed

[lazka]

See #582.

I'd still like to know if this is causing any problems and requires a new release.

[mgorny]

No, no real problems right now. Just a bit confusion, and if you don't specify the setuptools backend explicitly, then you're relying on (somewhat obsolete) legacy setuptools backend. No need to make a new release over this.

[lazka]

OK, thanks. I've merged #582

[lazka]

(as for the poetry/setuptools mix.. it allows me to use poetry for dev, while still providing a setup.py with some minimal metadata duplication)