https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96926
--- Comment #5 from Jason Merrill <jason at gcc dot gnu.org> --- (In reply to Jason Merrill from comment #4) > I think perhaps it's wrong to do substitution at this point because X has no > default argument. Giving it a default argument causes clang 10 to also > reject the testcase. ...but changing that doesn't help real testcases, since the tuple constructors do have default args for their constructor parms.
