In Windows, files are usually case insensitive. The program may not be able to change this, see
Meanwhile, SeenFileEntries keys in FileManager are case-sensitive, so we may end up with duplicate mappings in SeenFileEntries for the same file, for example
will all map to the same FileEntry.
Furthermore, the file name in FE will be the searched-for filename rather than the real filename. For example, let’s say you have hello.h on disk but you searched for HELLO.H. Since stat succeeds with HELLO.H this will be the filename linked from the FE and used in all clang’s diagnostics.
I’m not sure if this should be called a bug but it may not be what the user expects.
Fixing this would require extra work for every file open on Windows, checking not only that the searched-for file exists but checking what its real file name is and use it instead. I’m not sure if it’s worth the trouble either.