[clang] [Clang] Add [[clang::no_specializations]] (PR #101469)

[Nikolas Klauser via cfe-commits]

philnik777 wrote:

> Does it makes sense to also support function templates? For example, my understanding is that specializing `is_pointer_interconvertible_with_class()` would be UB

I can't find anything explicit about function template specializations, so I'm not 100% sure whether it's allowed. Since there is no requirement that the template arguments of any function match the standards-declared ones exactly, I don't think you're allowed to specialize _any_ standard library function.

https://github.com/llvm/llvm-project/pull/101469