[clang] [PATCH 1/7] [clang] Improve nested name specifier AST representation (PR #147835)

[Matheus Izvekov via cfe-commits]

mizvekov wrote:

> Hope that neither of these complicate your refactor! Looks like super impressive work; looking forward to seeing it land.

Thanks, that was very a very helpful summary!

I don't think this changes much about the design here, we will get a few new nested name kinds, and these will be less common than all of the existing ones, so we can put them in the slow path, changing `NamespaceAndPrefixStorage` into something which can store the new kinds, without that affecting the existing stuff significantly.

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