Fix macOS build failure by adding export ARCHFLAGS="-arch x86_64"

[yongtang]

This is an attempt to fix macOS build with system default python.

See giampaolo/psutil#1832 for similar issues.

Signed-off-by: Yong Tang yong.tang.github@outlook.com

[kvignesh1420]

@yongtang here are the things I have observed:

• Since you added /usr/bin to $PATH (export PATH=/usr/bin:$PATH) the github action is using python 3.8.2. However, the one readily available is 3.8.6 in /usr/local/bin.

+ which python3
/usr/local/bin/python3
+ python3 --version
+ python3 -c 'import site; print(site.getsitepackages())'
Python 3.8.6

Based on #1167.

• Also, I am not sure why the requirements.txt modification is required, as this PR: [github-action] fix macOS task #1167 passes without those changes. Is this because users have python3.7 as system default as of now? Also, this change might affect users trying to install the lint dependencies while using python3.8.

Please let me know if I am missing something here. Thanks.

[yongtang]

@kvignesh1420 As mentioned in #1167 (comment) the system default python3 (comes with macOS itself, not with Python.org download, brew, or pyenv, etc) is 3.8.2.

In GitHub Actions machines, brew was used to install additional versions of python3. So that is why you see /usr/local/bin/python3 as 3.8.6 (through brew), and /usr/bin/python3 as 3.8.2 (macOS system default).

If your macOS machine only comes from a clean OS install (no brew), then you will notice there is only /usr/bin/python3 (no /usr/local/bin/python3 existence)

Since there are too many ways to install python3, our README.md is trying to stay with system default python (user does not need brew or download Python3 from python.org). If instead we support python3 with brew install, users may very well ask for additional support with other python installations as well (e.g., download from python.org). We want to avoid ending up testing too many scenarios.

Thus export PATH=/usr/bin:$PATH is needed to bring system default python back on GitHub Action's machines.

Now there is a small glitch on system default python 3.8.2: In order to make our lint work, bazel will try to install regex package which needs to compile C/C++ code.

However, as of today the latest clang with XCode will try to build with options of -arch arm64 -arch x86_64. Obviously this is Apple's pre-support for the upcoming Apple Silicon (ARM based processor) macBook that is expected to release mid-november. However, this will cause a bug similar to giampaolo/psutil#1832

So some additional fix to avoid installation of regex is needed. In the early attempt I added additional conditions in requirements.txt to skip the regex pip package.

After looking through giampaolo/psutil#1832 it looks like merely adding export ARCHFLAGS="-arch x86_64" will be enough.

Note this measure is only temporarily. I expect Apple's macOS 11.0 (Big Sur) will fully address the issue mentioned above. (I am guessing Big Sur will be released mid-november as well when Apple Silicon ARM macBook is released).

Please take a look at the updated PR and see if that helps.

[kvignesh1420]

Thanks for the info @yongtang. It makes more sense now. I will close #1167 in favour of this.