There was a c++11_only dg-error in this testcase, for a "body of
constexpr function is not a return statement" diagnostic that was bogus,
but happened because the return statement was ill-formed. A change to
G++ earlier this month means that diagnostic is no longer emitted, so
remove the dg-error.
libstdc++-v3/ChangeLog:
* testsuite/20_util/tuple/comparison_operators/overloaded2.cc:
Remove dg-error for C++11_only error.
// { 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 }