sage_build_cython: Do not rely on CC environment variable being set #30876
Description
(from #30580):
src/sage_setup/command/sage_build_cython.py contains this code:
# Work around GCC-4.8 bug which miscompiles some sig_on() statements:
# * https://github.com/sagemath/sage-prod/issues/14460
# * https://github.com/sagemath/sage-prod/issues/20226
# * http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56982
if subprocess.call("""$CC --version | grep -i 'gcc.* 4[.]8' >/dev/null """, shell=True) == 0:
extra_compile_args.append('-fno-tree-copyrename')
This gives an (ignored) error when CC is not set -- which can happen if invoked outside of sage-env, for example when building an sdist.
$ python3 -u setup.py --no-user-cfg sdist >/tmp/res
/bin/sh: 1: --version: not found
We remove this code, which is obsolete after #33316 (Drop support for GCC < 6.3 in Sage 9.7)
CC: @dimpase @orlitzky @kiwifb
Component: build
Author: Matthias Koeppe
Branch/Commit: 805bf82
Reviewer: François Bissey
Issue created by migration from https://trac.sagemath.org/ticket/30876