Virutalenv support for building bottleneck

[Zeitsperre]

I have been trying to get Bottleneck to build from master using Python3.10 in the GitHub Actions environment. After finding the deadsnakes python action for installing the python-dev headers in Ubuntu 20.04 (https://github.com/deadsnakes/action), I was still having issues with the builds failing (despite everything working fine locally).

The fix to this issue raised here was actually solved by my colleague @aulemahal in another issue. I am opening this issue for context, with a PR incoming.

Explanation:

I believe I have found the source of the error, at least in my configuration. It is due to the specific of virtual environment creation with python -m venv.

When creating a virtual environment with venv into ${venv}, a ${venv}/include folder is created and sys.prefix == ${venv}. However, in opposition to virtualenv, the include folder is empty, it exists solely for files created by packages installed within the environment. Source : PEP 405.

The include folders needed by bottleneck are still accessible, but their path has to be constructed relative to sys.base_prefix instead, to get the system files. Changing:

bottleneck/bottleneck/src/bn_config.py

Line 30 in f2bc792

for prefix in [sys.prefix, sys.exec_prefix]:

to

    for prefix in [sys.prefix, sys.exec_prefix, sys.base_prefix]:

fixes the problem.

Of course, I have pythonX.X-dev installed (on ubuntu) for this to work.

EDIT: I have python 3.7.9.

Originally posted by @aulemahal in #348 (comment)

[chaseleif]

Thanks, this worked for me too. I was getting stuck on bottleneck not installing, this solved my issue.
Python 3.10.2, pip 22.0.3, Arch Linux 5.16.10

[Zeitsperre]

This appears to be fixed in the latest Bottleneck (v1.3.4). Thanks!