BUG: getauxval declaration invalid, causes compile issues

[jmgurney]

Describe the issue:

Trying to install numpy, (main branch) on FreeBSD/aarch64 (aka arm64), using clang, and I get the following compile error:

      INFO: cc: numpy/core/src/common/npy_argparse.c                                                                                                                                [133/1808]      INFO: cc: numpy/core/src/common/npy_hashtable.c                                                                                                                                               INFO: cc: numpy/core/src/common/npy_longdouble.c                                                                                                                                              INFO: cc: numpy/core/src/common/ucsnarrow.c                                                                                                                                                   INFO: cc: numpy/core/src/common/ufunc_override.c                                                                                                                                              INFO: cc: numpy/core/src/common/numpyos.c                                                                                                                                                     INFO: cc: build/src.freebsd-14.0-CURRENT-arm64-3.9/numpy/core/src/common/npy_cpu_features.c                                                                                             
      numpy/core/src/common/npy_cpu_features.c.src:586:22: error: static declaration of 'getauxval' follows non-static declaration                                                            
      static unsigned long getauxval(unsigned long k)                                                                                                                                         
                           ^                                                                                                                                                                  
      numpy/core/src/common/npy_cpu_features.c.src:582:37: note: previous declaration is here                                                                                                 
      __attribute__((weak)) unsigned long getauxval(unsigned long); // linker should handle it                                                                                                
                                          ^                                                                                                                                                   
      1 error generated.                                                                                                                                                                      

It is very clear that this is the case by code inspection:
https://github.com/numpy/numpy/blob/main/numpy/core/src/common/npy_cpu_features.c.src#L582

Reproduce the code example:

# I can't install numpy so there is no code to reproduce.

Error message:

# see above.

NumPy/Python version information:

Main branch as of a few minutes before I filed this issue, the install was attempted via:

pip install git+https://github.com/numpy/numpy.git

Python version:

Python 3.9.12 (main, Mar 27 2022, 01:58:04) 
[Clang 13.0.0 (git@github.com:llvm/llvm-project.git llvmorg-13.0.0-0-gd7b669b3a on freebsd14

FreeBSD version info:

FreeBSD generic 14.0-CURRENT FreeBSD 14.0-CURRENT #0 main-n254105-d53927b0bae: Thu Mar 31 09:26:31 UTC 2022     root@releng1.nyi.freebsd.org:/usr/obj/usr/src/arm64.aarch64/sys/GENERIC arm64

[jmgurney]

Looks like this commit is the problem:
c47e962

Done by @devnexen

[jmgurney]

Just for reference, the previous commit works just fine:

pip install 'git+https://github.com/numpy/numpy.git@5c7002926ec8ad12785b36024f9da80b7017ad1c#egg=numpy'

[charris]

Would you like to make a PR?

[seberg]

Sounds like the issue is that getauxval already exists (presumably correct). Can we just add a check for that, the code assumes that on #ifdef __FreeBSD__ it does not exist.

[jmgurney]

I'll do a PR if someone tells me what the correct fix is?

Or are you suggesting that I reverse the change that broke things?

[mattip]

This came from #18169 which has no comments about the need for this code. Perhaps clang and gcc differ here? In any case, the conservative move would be to fix the current code. It would be nice if @devnexen could explain how they tested #18169 and why they needed to add the wrapper around elf_aux_info. We don't run FreeBSD in our CI.

[devnexen]

I'll do a PR if someone tells me what the correct fix is?

I might suggest to guard for Linux only the line 582.

[kevans91]

This came from #18169 which has no comments about the need for this code. Perhaps clang and gcc differ here? In any case, the conservative move would be to fix the current code. It would be nice if @devnexen could explain how they tested #18169 and why they needed to add the wrapper around elf_aux_info. We don't run FreeBSD in our CI.

FWIW, the wrapper around elf_aux_info is pertinent because we (FreeBSD) can't/won't provide a compatible getauxval() implementation. Some software (I have no idea the magnitude) assumes the presence means some Linux-specific AT_* values are defined. We provide HWCAP/HWCAP2, but beyond that it can get a bit shadier.

re: CI, I don't have time at the moment, but would the numpy project accept the addition of Cirrus CI if a PR comes along that adds it? I think Cirrus is just about the best game in town for FreeBSD runners.