[libcxx-commits] [libcxx] [libc++] Remove macros for keeping std::allocator members and void specialization after C++20 (PR #85806)

[Ilya Biryukov via libcxx-commits]

ilya-biryukov wrote:

Please let me know if removal of `_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_VOID_SPECIALIZATION` in this patch is controversial. I can see why someone would want to go with a more conservative approach (e.g. deprecate it in LLVM 19 and remove in LLVM 20), although my proposal would be to remove it right away. Happy to update this PR to go the other way.

I would also like to get feedback on the test updates as I wasn't sure I was taking all the right turns there.

https://github.com/llvm/llvm-project/pull/85806