Support for Gcov coverage in extensions

What's the problem this feature will solve?

I have a Python package with a Pybind11 extension and I'd like to create coverage reports for both the Python and the C++ code. I can do this by doing the following running:

CFLAGS="-coverage" python setup.py build_ext --inplace
coverage run -m pytest ...
find src -type f -name '*.cpp' | xargs -I{} gcov -o build/temp*/src {}

This works because -coverage adds .gcno files in the build directory, which coverage recognizes and creates .gcda files. Finally gcov is used to create gcov files.

Describe the solution you'd like

Instead of using old not recommended python setup.py, I'd rather do something like:

CFLAGS="-coverage" pip install -e .

and have setup.cfg with:

[build_ext]
inplace=1

be enough to get a build directory with .gcno in it.

Alternative Solutions

Yes with old python setup.py

Additional context

Obviously this assumes gcov is installed on the system.

Code of Conduct

• I agree to follow the PSF Code of Conduct.

Start with the editable-install flow using CFLAGS="-coverage" pip install -e ., and compare it with the setup.py build_ext --inplace command in the issue. Inspect setup.cfg, including its [build_ext] section, and verify that the resulting build directory contains .gcno files for the extension. Done means gcov coverage artifacts can be produced without invoking setup.py directly.