Also restore the test for 'a < a' that was removed by r12-2537 because
it is ill-formed. We still want to test operator< for tuple, we just
need to not use std::nullptr_t in that tuple type.
libstdc++-v3/ChangeLog:
* testsuite/20_util/tuple/comparison_operators/overloaded.cc:
Restore test for operator<.
* testsuite/20_util/tuple/comparison_operators/overloaded2.cc:
Adjust expected errors for C++20.
auto a = std::make_tuple(nullptr, Compares{}, 2, 'U');
auto b = a == a;
+
+#if ! __cpp_lib_three_way_comparison
+// Not valid in C++20, because TwistedLogic doesn't model boolean-testable.
+auto c = std::make_tuple("", Compares{}, 2, 'U');
+auto d = c < c;
+#endif
auto a = std::make_tuple(nullptr, Compares{}, 2, 'U');
auto b = a < a;
-// { dg-error "ordered comparison" "" { target *-*-* } 0 }
+// { dg-error "no match for 'operator<'" "" { target c++20 } 0 }
+// { dg-error "no match for .*_Synth3way|in requirements" "" { target c++20 } 0 }
+// { dg-error "ordered comparison" "" { target c++17_down } 0 }
// { dg-error "not a return-statement" "" { target c++11_only } 0 }