Cross-compiled macosx_arm64: do the extensions that link with npymath.a (npyrandom.a) actually work? #173
Description
@matthew-brett, I have a question for a cross-compile scipy build for macosx_arm64. When I carry out a cross-build I get several warnings when an extension tries to link to npymath.a. This is because the installed version of numpy on the build computer is for x86_64.
ld: warning: ignoring file /private/var/folders/24/8k48jl6d249_n_qfxwsl6xvm0000gn/T/pip-build-env-dlv4s5j4/overlay/lib/python3.10/site-packages/numpy/core/include/../lib/libnpymath.a, building for macOS-arm64 but attempting to link with file built for macOS-x86_64
The build warning is here.
Given that the MacPython/scipy-wheels repo is trying to do the same thing I thought I'd have a look and see if it'd solved this issue. However, I think it's got the same issue:
/opt/gfortran-darwin-arm64/bin/arm64-apple-darwin20.0.0-gfortran -Wall -g -Wall -g -undefined dynamic_lookup -bundle -arch arm64 -L/opt/arm64-builds/lib -Wl,-rpath,/opt/arm64-builds/lib -L/opt/gfortran-darwin-arm64/lib/gcc/arm64-apple-darwin20.0.0/10.2.1 -Wl,-rpath,/opt/gfortran-darwin-arm64/lib/gcc/arm64-apple-darwin20.0.0/10.2.1 build/temp.macosx-11.0-arm64-3.8/scipy/special/_ufuncs.o build/temp.macosx-11.0-arm64-3.8/scipy/special/sf_error.o build/temp.macosx-11.0-arm64-3.8/scipy/special/amos_wrappers.o build/temp.macosx-11.0-arm64-3.8/scipy/special/cdf_wrappers.o build/temp.macosx-11.0-arm64-3.8/scipy/special/specfun_wrappers.o build/temp.macosx-11.0-arm64-3.8/scipy/special/_cosine.o -L/opt/arm64-builds/lib -L/Users/runner/work/1/s/venv/lib/python3.8/site-packages/numpy/core/lib -L/opt/gfortran-darwin-arm64/bin/../lib/gcc/arm64-apple-darwin20.0.0/10.2.1 -L/opt/gfortran-darwin-arm64/bin/../lib/gcc/arm64-apple-darwin20.0.0/10.2.1 -L/opt/gfortran-darwin-arm64/bin/../lib/gcc/arm64-apple-darwin20.0.0/10.2.1 -Lbuild/temp.macosx-11.0-arm64-3.8 -Wl,-rpath,/opt/arm64-builds/lib -lsc_amos -lsc_cephes -lsc_mach -lsc_cdf -lsc_specfun -lopenblas -lopenblas -lnpymath -lgfortran -o build/lib.macosx-11.0-arm64-3.8/scipy/special/_ufuncs.cpython-38-darwin.so
ld: warning: ignoring file /Users/runner/work/1/s/venv/lib/python3.8/site-packages/numpy/core/lib/libnpymath.a, building for macOS-arm64 but attempting to link with file built for macOS-x86_64
C compiler: clang++ -Wno-unused-result -Wsign-compare -Wunreachable-code -fno-common -dynamic -DNDEBUG -g -fwrapv -O3 -Wall -g -arch arm64 -arch arm64 -arch arm64 -I/opt/arm64-builds/include -arch arm64
The build log for that output is here. I think the installed version of numpy for the arm64 part of the multibuild is macosx_x86_64
My question is, do these cross-compiled arm64 extensions that link to npymath (or npyrandom) actually work? We can't actually test them on the build machine because its the wrong architecture.