https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124457
--- Comment #4 from Jason Merrill <jason at gcc dot gnu.org> --- Part of the issue with AlsoTrue is that we still represent the return-type-requirement as a constrained auto, as a legacy of the Concepts TS implementation, but that's mostly a distraction... ...because the f3 case is in fact a placeholder, and I still think it should be accepted; we shouldn't reject a type-constraint based on where it's used. We'll eventually take the reflection of the deduced type. make_constrained_placeholder_type could do something to obscure the placeholderness across the call to build_concept_check?
