Hello, I work on the Microsoft standard standard library and we encountered a build failure upon enabling std::format in /std:c++latest mode.
This showed up in commit 4c263ed, it's "fixed" in main, but the underlying issue festers and will cause a new failure if headers are rearranged such that GIMatchDiag.cpp sees the content of <format>.
On C++ standard versions that have std::format these calls become ambiguous with std::format due to ADL triggered by the unique_ptr* parameters.
On another note it's a little odd to format &N as a pointer when N is a unique_ptr, that's for someone else to consider though, I don't know enough about the code in question.
This is my first patch for llvm, so do let me know if I've screwed up the submission process.