travis unix linux builds can't find gcc sometimes

[itsayellow]

Describe the bug
Travis linux builds seem to fail occasionally. The culprit seems to be packages that need gcc to install cannot find gcc.

unable to execute 'gcc': No such file or directory
error: command 'gcc' failed with exit status 1

How to reproduce

Run code through Travis CI tests

Expected behavior

if local tests pass, they should pass on Travis, but often they fail.

[itsayellow]

https://travis-ci.org/pipxproject/pipx/builds/604553890?utm_source=github_status&utm_medium=notification

That one seems to have a passing test for python3.6, and a failing one for python3.7. The failing test has the missing gcc problem.

Is this a Travis problem?

[itsayellow]

Could this have anything to do with us removing sudo from .travis.yml ? #243

[itsayellow]

I just saw a weird error running make test on my local computer, similar but different, while a test was trying to install black.

  In file included from regex_3/_regex.c:48:
  /usr/local/Cellar/python/3.7.4_1/Frameworks/Python.framework/Versions/3.7/include/python3.7m/Python.h:25:10: fatal error: 'stdio.h' file not found
  #include <stdio.h>
           ^~~~~~~~~
  1 error generated.
  error: command '/Library/Developer/CommandLineTools/usr/bin/clang' failed with exit status 1

Oddly the other python versions worked fine.

[itsayellow]

This seems to happen in particular with the linux python 3.7 tests.

That one uses dist: xenial so I tried removing it to see if that helped. It did not help.

[michaeljoseph]

psf/black#1112 👀