CMake files-api warning in sdist phase

[eirrgang]

For a very simple project that include tool.scikit-build.sdist.cmake = true, the sdist phase of python -m build produced

2025-08-15 09:45:24,342 - scikit_build_core - WARNING - Could not parse CMake file-api

on a Mac with cmake 4.0.3 and Python 3.10.

python -m scikit_build_core.file_api.reply build/.cmake/api/v1/reply produced

...
            | Traceback (most recent call last):
            |   File ".../.venv10/lib/python3.10/site-packages/scikit_build_core/file_api/reply.py", line 71, in make_class
            |     input_dict[field.name] = self._convert_any(
            |   File ".../.venv10/lib/python3.10/site-packages/scikit_build_core/file_api/reply.py", line 104, in _convert_any
            |     return self._convert_any(item, get_args(target)[0])
            |   File ".../.venv10/lib/python3.10/site-packages/scikit_build_core/file_api/reply.py", line 98, in _convert_any
            |     return self.make_class(item, target)
            |   File ".../.venv10/lib/python3.10/site-packages/scikit_build_core/file_api/reply.py", line 88, in make_class
            |     return target(**input_dict)
            | TypeError: Link.__init__() missing 1 required positional argument: 'commandFragments'
            | Failed to convert field 'link' of type typing.Optional[scikit_build_core.file_api.model.codemodel.Link]
            +——————————————————

The TypeError occurs when data[json_field] is {'language': 'CXX'}. I.e. when _convert_any tries to call scikit_build_core.file_api.model.codemodel.Link(language="CXX")

No warning was produced during the build phase.

[LecrisUT]

Yes, this is bound to happen because the cmake file-api does not follow the latest cmake version, nor is it version aware. I've tried to look into how to do it, but didn't manage to come up with something.

Currently though it is inconsequential because the PRs that use it are still to be reviewed and those features will be experimental gated for a while.