Add support for CIBW_ENVIRONMENT

[pllim]

I need something like this to build wheel for Python 3.12 for packages with C stuff that needs unreleased numpy 1.26b. Unfortunately, I don't know if it is possible from your workflow here. Please help. Thanks!

https://github.com/scipy/scipy/blob/34366e000b3f37732c4254476e0d6df1857f1f70/.github/workflows/wheels.yml#L136C11-L136C27

Related PRs:

• Add Python 3.12 job and wheels liberfa/pyerfa#111
• TST: Test against Python 3.12 pre-prelease astropy/astropy#14784 or Add nightly wheels for Python 3.12 astropy/astropy#15202

[ConorMacBride]

I think this should already be possible with the env option. Please let me know if that works

[pllim]

Indeed, env works. Thanks!

[pllim]

So while this works, it also un-discriminatorily pulls down numpy 1.26b for everything, not just the cp312 stuff. This also breaks all the win32 jobs because I guess this new numpy does not ship win32 wheels no more.

      env: |
        CIBW_ENVIRONMENT: PIP_PRE=1

What is the best way to tell the workflow to only do it for certain Python version here? Or do I need a totally separate workflow just for cp312.

[ConorMacBride]

You could try:

env: |
    CIBW_ENVIRONMENT: 'PIP_PRE=$( if [ "${CIBW_BUILD:0:5}" = "cp312" ]; then echo 1; else echo 0; fi )'

A neater solution might be to configure CIBW_BEFORE_ALL, either as an env var or in pyproject.yaml. It could call a script that sets env vars.

[pllim]

Alas, something isn't quite right in the if-else syntax you provided. The "else" seems to work but "then" failed to assign 1 to the variable. I get this:

e476a803-2995-460c-b317-5d3068b425a5.sh: 3: Bad substitution
{
  "CIBW_ENVIRONMENT": "PIP_PRE="
}
...
CIBW_ENVIRONMENT: PIP_PRE=
CIBW_BUILD: cp312-manylinux_x86_64