so that they can be defined in one translation unit while the class is
declared multiple times.

Actually, they appear only in the AST generated by clang-11.

especially if half of them are not seen as implicit afterwards. This can't end
well 

it seems that this is not consistent across clang versions.

Now that we use more systematically the Filepath.Normalized version of
filenames, this shows in clang messages as absolute filenames in location.
To have reproducible oracles, the pwd component must be filtered out.