Allow installation of debug version of Python

[YannickJadoul]

It would be useful if the GitHub Action could also easily install and setup a debug version of Python. This PR recognizes a -dbg suffix, and also install the debug version and uses it to setup the virtual environment.

Since there are no tests, I am already using my branch in the CI runs here, and it seems to work: pybind/pybind11#2746

Things to consider:

• -dbg-dev or -dev-dbg isn't recognized/allowed, but the nightly builds don't seem to have a debug version?
• Another option would be to add another argument to the action dbg: true or debug: true; this might make more sense if the nightly builds would have a debug build, but if they don't, it might be unexpected that such a combination would not work?
• The virtual environment is still created in ~/venv-{version}. Should this be ~/venv-{version}-dbg, such that two installations of the same version could coexist as debug and non-debug build? But then -dev doesn't currently allow this either, it seems.

[asottile]

but the nightly builds don't seem to have a debug version?

They totally do! They're basically the same packages but without docs, libpython symbols, and the news file: https://github.com/deadsnakes/nightly#limitations

Should this be ~/venv-{version}-dbg

Hmmm, this is a good point -- for now it's probably fine to keep them the same -- if someone has a usecase for doing both at the same time then this can be enhanced later

[YannickJadoul]

They totally do! They're basically the same packages but without docs, libpython symbols, and the news file: https://github.com/deadsnakes/nightly#limitations

Oh, do you then prefer to have a separate option, to support all 4 combinations (released vs. nightly, debug vs. release), rather than the 3 versions now (release, debug, nightly)? E.g. something like this:

    strategy:
      matrix:
        python-version: [3.9, 3.9-dev]
        debug: [true, false]

      steps:
      - uses: deadsnakes/action@vx.y.z
        with:
          python-version: ${{ matrix.python-version }}
          debug: ${{ matrix.debug }}

[asottile]

They totally do! They're basically the same packages but without docs, libpython symbols, and the news file: https://github.com/deadsnakes/nightly#limitations

Oh, do you then prefer to have a separate option, to support all 4 combinations (released vs. nightly, debug vs. release), rather than the 3 versions now (release, debug, nightly)? E.g. something like this:

    strategy:
      matrix:
        python-version: [3.9, 3.9-dev]
        debug: [true, false]

      steps:
      - uses: deadsnakes/action@vx.y.z
        with:
          python-version: ${{ matrix.python-version }}
          debug: ${{ matrix.debug }}

Yeah that probably makes sense

[YannickJadoul]

Let's see if this works :-) I've pushed an update to pybind/pybind11#2746

[YannickJadoul]

Seems so; if I didn't mess up the original use, with debug: false or without debug input, this should work.

[asottile]

[YannickJadoul]

Great! Thanks for the smooth merge & release!

[asottile]

and thank you for the patch! <3