HI Johannes, sorry for the delayed reply.
The regex that is already there sort of “accidentally” works for clang as c is higher up in the alphabet than any other LLVM subproject.
The coding guidelines say that the sorting of header includes should be in the order of most specific to least specific LLVM subproject.
This is very likely going to be different for each individual subproject, so I think this is one case where divergence from the main LLVM style is easy to argue aligns us better with the actual intended coding guidelines.
For example, in our case we want the order flang → fir → MLIR → clang → LLVM, but this isn’t the order that e.g. libc++ would want. I don’t think this difference is captureable in the global style.
Thanks
David Truby