[FR] Multiple call to find_package from setup.cfg

What's the problem this feature will solve?

I am willing to convert from setup.py to setup.cfg a package that does something like the following:

setup(
    packages=find_package() + find_package("ext/"),
)

The first call find the main package and the second find other packages that are distributed along with the main one but not from the same author (and not distributed otherwise).

Describe the solution you'd like

One way that feature could be achieved would be by extending the where keyword from options.packages.find to support a list of roots like that:

[options.packages.find]
where =
    ./
    ./ext

An alternative approach would be to add another level of subsection, possibly specified by a list of labels in the main options sections:

[options]
packages = find: main, external

[options.packages.find.main]
where = ./

[options.packages.find.external]
where = ./ext

Alternative Solutions

No response

Additional context

If that is a feature that may be accepted, I am willing to implement it myself.

Code of Conduct

• I agree to follow the PSF Code of Conduct

No source files, tests, or entry points are named. Start by reviewing how setup.cfg currently handles options.packages.find and package discovery, then clarify which proposed configuration form should be implemented; done means multiple package roots are supported and the behavior is covered by tests.