[clang] [clang-tools-extra] [clang] Improve nested name specifier AST representation (PR #147835)

[Matheus Izvekov via cfe-commits]

mizvekov wrote:

> We started to see a CI failure around the time this PR landed in https://green.lab.llvm.org/job/llvm.org/job/clang-stage2-Rthinlto/1079/
> Any ideas what might be going on here?

@Xazax-hun this could be the same as https://github.com/llvm/llvm-project/issues/153933

Could you confirm if the hang is limited to assertions enabled llvm builds, and if https://github.com/llvm/llvm-project/pull/153996 is sufficient to fix the problem?

https://github.com/llvm/llvm-project/pull/147835