[clang] [llvm] [Clang] restrict use of attribute names reserved by the C++ standard (PR #106036)

[Richard Smith via llvm-commits]

zygoloid wrote:

Oh, I see, you're suggesting we remove the `getStdNamespace` check from this PR. Yeah, I think that's reasonable.

But I'd somewhat question whether this PR and warning really has anything to do with the attribute names being "reserved" at that point -- we're not checking whether they're reserved or not, and it really doesn't matter. Warning on a `#define` that clobbers the name of a standard attribute is just generally a good thing to do, regardless of whether you're using the standard library.

https://github.com/llvm/llvm-project/pull/106036