https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103923
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2022-01-06
Status|UNCONFIRMED |NEW
Ever confirmed|0 |1
--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
The problem is actually that the auto return type can't be deduced while the
enclosing class is incomplete, not that H is incomplete.
N.B. You can fix your code by simply changing the return type to not use auto:
struct H {
int operator()(const K &) const { return 0; }
};
In any case, I think changing libstdc++ to make the code ill-formed would be an
improvement than silently compiling it but getting the traits wrong.
