https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95540
--- Comment #4 from Iain Sandoe <iains at gcc dot gnu.org> --- (In reply to Michael Bruck from comment #3) > I think you misread, I was complaining about it passing the closure to the > traits/constructor/allocator. But if that is what was agreed upon... > > Can the closure object that is being passed to the constructor and allocator > be used for anything? I am asking because I got it to pass nullptr with the > code below. But if there is no legitimate use it might as well always pass a > nullptr. OK.. I think I did misread (I was under the impression you wanted better diagnostics for the case where the user had intentionally specialised the traits - but made an error). [FTR, I am not sure if that's feasible - but someone with more specialisation-fu can comment on that]. --- I think we need the closure object type in the traits lookup because: Since the coroutine traits are global, and the closure type is unique, that provides a way to disambiguate instantiations of the traits for lambdas with otherwise identical signatures. The callable is usable in the other positions - I don't think that was particularly in debate. The issue was about whether we should pass a reference to the closure or the pointer (and it was decided that symmetry with the class object that a reference was the intention). The fix is not yet in master (to make it a reference) - it's pending review (but you could apply it to test things out).
