[CI][Python] Cython test is failing in conda packaging builds

[jorisvandenbossche]

See for example this log output of the latest conda-linux-x64-cpu-py3 build.

The test_cpp_extension_in_python is failing, which is a test building some custom cython, and it's failing with

...
            # Compile extension module
>           subprocess.check_call([sys.executable, 'setup.py',
                                   'build_ext', '--inplace'],
                                  env=subprocess_env)

...
>           raise CalledProcessError(retcode, cmd)
E           subprocess.CalledProcessError: Command '['$PREFIX/bin/python3.11', 'setup.py', 'build_ext', '--inplace']' returned non-zero exit status 1.

../../../subprocess.py:413: CalledProcessError
----------------------------- Captured stdout call -----------------------------
Compiling extensions.pyx because it changed.
[1/1] Cythonizing extensions.pyx
Extension module: <setuptools.extension.Extension('extensions') at 0x7f8bfb469c90> ['$PREFIX/lib/python3.11/site-packages/numpy/core/include', '$PREFIX/lib/python3.11/site-packages/pyarrow/include'] ['arrow_python', 'arrow'] ['$PREFIX/lib/python3.11/site-packages/pyarrow', '$PREFIX/lib']
running build_ext
building 'extensions' extension
creating build
creating build/temp.linux-x86_64-cpython-311
gcc -pthread -B $PREFIX/compiler_compat -DNDEBUG -fwrapv -O2 -Wall -fPIC -O2 -isystem $PREFIX/include -fPIC -O2 -isystem $PREFIX/include -fPIC -I$PREFIX/lib/python3.11/site-packages/numpy/core/include -I$PREFIX/lib/python3.11/site-packages/pyarrow/include -I$PREFIX/include/python3.11 -c extensions.cpp -o build/temp.linux-x86_64-cpython-311/extensions.o -std=c++17
----------------------------- Captured stderr call -----------------------------
error: command 'gcc' failed: No such file or directory

So it's complaining about "gcc" not found. I don't know if this test is supposed to work on those builds, but the strange thing is that we have other tests that call the exact same subprocess command, and those are not failing.

[jorisvandenbossche]

This seems to have been fixed by #34652

[h-vetinari]

Yes, I added a compiler to the test requirements, so gcc will be found on linux