BUG: Bus error: 10

[ljlamarche]

Describe the bug
I can install apexpy (seemingly successfully), but when I try to import the module my python session crashes with a "Bus error: 10".

>>> import apexpy
Bus error: 10

To Reproduce
Steps to reproduce the behavior:

1. Clone repo and install with $ pip install .
2. Start python session on CLI
3. Import apexpy module >>> import apexpy
4. Error will also be generated by running pytest

Expected behavior
The apexpy module will be imported and can be used in code.

Computer (please complete the following information):

• OS: MacOS Monterey 12.1
• Python version: 3.9.9
• Compiler with version: gfortran 11.0.0
• Apexpy version/branch: 1.1.0, main and develop

Additional context
This computer has one of the Apple M1 Pro chips, and I installed gfortran from HPC. I'm using python from miniconda 4.10.1.

[ljlamarche]

This appears to be related to a known issue with Apple Silicon:
Homebrew/homebrew-core#69236
Homebrew/homebrew-core#70096
scipy/scipy#13364
iains/gcc-darwin-arm64#32
Homebrew/discussions#415
scipy/scipy#13998

(Links are in no particular order, but it seems to be a large problem for the scipy community.) I don't fully understand what's going on here, but it seems to be related to unaligned memory? I've managed to install apexpy successfully (after first installing gfortran and numpy) with the following command:

CFLAGS="-falign-functions=8 ${CFLAGS}" pip install --no-binary :apexpy: apexpy

The following links may be helpful for a more permanent solution, but I haven't looked into it in detail yet:
scipy/scipy#14151
scipy/oldest-supported-numpy#20

[aburrell]

This has now been added to the docs.