https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102350
--- Comment #17 from Jakub Jelinek <jakub at gcc dot gnu.org> --- You'd need a different builtin (so that you know the presence of the builtin means the new behavior), ideally tell the builtin some way the type it should construct objects in (as opposed to std::source_location::__impl), because otherwise you don't know how __builtin_source_location will behave (except for libstdc++ where for GCC we expect to support only the same GCC/libstdc++ combo). But more importantly, how would you use the builtin? I expect not using the builtin directly, so through a macro? Otherwise, if it is some inline function, you'd most likely get the location of the inline function and not that of the caller. That is part of the magic std::source_location::current behavior where exactly takes the location from for the builtin...
