[clang] [clang] pointer to member with qualified-id enclosed in parentheses in unevaluated context should be invalid (PR #89713)

[Hubert Tong via cfe-commits]

hubert-reinterpretcast wrote:

> Or is there a deeper issue here and I'm not seeing it?

The previous Clang behaviour produced the wrong type as the result. So the choices are to:

1. Do the old wrong thing: silent incorrect behaviour
2. Do the new wrong thing: produce diagnostic that may confuse users
3. Fix the type associated with the expression

https://github.com/llvm/llvm-project/pull/89713