In reply to @reckenrode:matrix.org
I think depsBuildBuild should work. The new SDK stuff supports it, so I should be able to add the 15.0 SDK there as well.

Trying to fix cross-compilation for countourpy. It stores information about its build environment in a .py file, including the path to the Python executable.

What's the right way to go about making this cross compile properly? The build environment file is generated using the builder Python. The simplest option I can see is just using substituteInPlace in post-build to replace the build Python with the target Python, but it feels a bit hacky.

And check that output doesn't depend on build deps

nix path-info -r ./result look for paths without the target suffic

This is what I'm looking to fix:

error: output '/nix/store/gnk9kd5j28wm94m0pfk21rdbyzyvkypd-python3.12-contourpy-1.2.1-aarch64-unknown-linux-gnu' is not allowed to refer to the following paths:
         /nix/store/wfbjq35kxs6x83c3ncpfxdyl5gbhdx4h-python3-3.12.6

The only reference to the wrong Python is in this build info file.

In reply to @jackwilsdon:matrix.org
We could patch this and do a substitute on the patch before applying it, but not sure if that's really any better: https://github.com/contourpy/contourpy/blob/27160ab9a3f2d32f8d6b1990ae2919475c322283/lib/contourpy/util/meson.build#L23

Testing this:

    postBuild = lib.optionals (stdenv.hostPlatform != stdenv.buildPlatform) ''
      find . -name __pycache__ -type d -depth -delete
      substituteInPlace util/_build_config.py \
        --replace-fail ${python.pythonOnBuildForHost.interpreter} ${python.interpreter}
    '';

$ nix path-info -r ./result | grep -v aarch64-unknown-linux
/nix/store/iv4iygkdy52b8vawy0b5aqxi7lpk7afy-cross-file.conf

seems promising!