Description

The doc said:

The user can supply configuration settings using the --config-settings command line option (which can be supplied multiple times, in order to specify multiple settings).

If setting multiple times like this:

pip wheel --config-settings="--build-option=--cffi" --config-settings="--build-option=--avx2" -v .

Only the last option is passed to backend: {'--build-option': '--avx2'}

It seems these code let the last option override the previous options:

Expected behavior

All options are passed to backend: {'--build-option': ['--cffi', '--avx2']}

Modify the code like this:

    if dest is None:
        dest = {key: []}
        setattr(parser.values, option.dest, dest)
    dest[key].append(val)

pip version

22.3.1

Python version

3.10

OS

Windows 11

How to Reproduce

1. define a custom PEP-517 hook get_requires_for_build_wheel
2. let the hook print the config_settings argument

    def get_requires_for_build_wheel(config_settings=None):
        print('config_settings argument:', config_settings)
        return []

Output

No response

Code of Conduct

• I agree to follow the PSF Code of Conduct.