Building macos_x86_64 and macos_arm64 with gfortran support

[ragonneau]

I am building a Python library using cibuildwheel and gfortran for macOS on GitHub Actions. Since they do not provide ARM architectures of macOS, I have to build it using cross-compilation. To install gfortran, I use the MacPython installer, but the wheel repairing stage fails because the Fortran libraries are not found.

Did anyone face the same issue and solved it?
Thanks!

[MrBitBucket]

I am having the same issue with a python extension. I can build the required libs/includes offline and get the setup.py to download those as resources. Then I am trying to use https://cibuildwheel.readthedocs.io/en/stable/faq/#macos-passing-dyld_library_path-to-delocate
to make things work. I eventually put the lib/include folders underneath /tmp/mycache and that allowed the M1 wheel to include the arm64 dylib.

[ragonneau]

Brilliant, thank you very much! It was the final key to the answer. I installed gfortran using the gfortran-install repository. I then linked manually the DYLD library to /usr/local/gfortran/lib and I placed in my pyproject.toml the following code:

[tool.cibuildwheel.macos]
archs = "x86_64 arm64"
test-skip = "*_arm64 *_universal2:arm64"
environment = { CFLAGS="-std=c99 -fno-strict-aliasing", CC="clang", CXX = "clang++" }
repair-wheel-command = [
    "DYLD_LIBRARY_PATH=/usr/local/gfortran/lib delocate-listdeps {wheel}",
    "DYLD_LIBRARY_PATH=/usr/local/gfortran/lib delocate-wheel --require-archs {delocate_archs} -w {dest_dir} {wheel}"
]