[PATCH] PR libstdc++/98842: Fixed Constraints on operator<=>(optional, U)

[Seija K. via Gcc-patches]

The original operator was underconstrained. _Up needs to fulfill
compare_three_way_result,
as mentioned in this bug report
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98842

diff --git a/libstdc++-v3/include/std/optional
b/libstdc++-v3/include/std/optional
index 8b9e038e6e510..9e61c1b2cbfbd 100644
--- a/libstdc++-v3/include/std/optional
+++ b/libstdc++-v3/include/std/optional
@@ -1234,7 +1234,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     { return !__rhs || __lhs >= *__rhs; }

 #ifdef __cpp_lib_three_way_comparison
-  template<typename _Tp, typename _Up>
+  template<typename _Tp, three_way_comparable_with<_Tp> _Up>
     constexpr compare_three_way_result_t<_Tp, _Up>
     operator<=>(const optional<_Tp>& __x, const _Up& __v)
     { return bool(__x) ? *__x <=> __v : strong_ordering::less; }