@mhsmith Do you know why pybind11 isn't found? It should be in the build temporary venv, and scikit-build-core is adding the site-packages to the CMAKE_MODULE_PATH.

This is because of the set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY) that cibuildwheel adds to the CMake toolchain. I copied that from the CMake documentation, but it's not correct in this case because it prevents build systems from loading non-platform-specific packages from outside of the root path.

I've fixed this in pypa/cibuildwheel#2547.

Note to my future self: the relevant variable is CMAKE_PREFIX_PATH, which scikit-build-core sets to the venv's site-packages directory. This works because one of the many paths that find_package searches is <prefix>/<name>*/(lib/<arch>|lib*|share)/cmake/<name>*/, and the pybind installation has its cmake files in pybind11/share/cmake/pybind11.

@mhsmith Seem to be getting a timeout error? Is that expected? Same issue in scikit-hep/boost-histogram#1045.

Edit: ahh, I see "GitHub Actions can't currently run the Android emulator on macOS" in pybind11. I'll try to copy what's in there.