[clang] [serialization] no transitive decl change (PR #92083)

[Ilya Biryukov via cfe-commits]

ilya-biryukov wrote:

I added a printf into `FindExternalVisibleDeclsByName` where it calls find on `MultiOnDiskHashTable` to see what names have been causing this and I can see that we stall on the first name we try to look up. The name `std` is the first one and was previously processed almost instantly and now it takes >5 minutes to return results for it. I believe this is where most, if not all, of the overhead is coming from.

Will be digging more, but maybe this gives some clues to where the problem is.



https://github.com/llvm/llvm-project/pull/92083