[Bug libstdc++/93147] std::tuple of empty structs with member equality operators has ambiguous equality operator

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93147

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |rejects-valid
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2020-01-03
     Ever confirmed|0                           |1

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Reduced:

struct A {
  bool operator == (A) const { return true; }
};

struct B {
  bool operator == (B) const { return true; }
};

struct Tuple_base : private A { };
struct Tuple_impl : Tuple_base, private B { };

struct Tuple : Tuple_impl { };

bool operator==(Tuple, Tuple) { return true; }

bool example(Tuple a, Tuple b)
{
  return a == b;
}