[clang] [Clang] [Sema] Improve support for `__restrict`-qualified member functions (PR #83855)

[Erich Keane via cfe-commits]

https://github.com/erichkeane commented:

I did a review, but didn't stop to decide whether we SHOULD :)  Aaron should be around 'sometime' to make that judgement, my restrict knowledge/reasoning is slim/none.

https://github.com/llvm/llvm-project/pull/83855