Resending from the right email account....

We looked at in the LWG telecon today. It proposes to add a __cpp_lib_atomic_compat macro.

It was pointed out that "compat" is a bit generic and could mean different things in different contexts. Should we instead name the macro after the header? I think that's our policy when there's no reason to do otherwise. It's complicated here by the header being <stdatomic.h> and we can't have a dot in a macro name.

Should it be __cpp_lib_stdatomic_h then?