https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89022
--- Comment #2 from emsr at gcc dot gnu.org --- I think we're done. The __cpp_lib_constexpr may not do anything or may not be in the newest drafts anymore. We should probably kill it. I was very confused as people were going back and forth about constexpr lib macros. I still owe the patch for misc. constexpr bits. That's not really this PR though (<algorithm>. It's stuff like pair ctors, insert iterators, etc.
