From 6944fdb20da8065004dc81052aa05e13cef39998 Mon Sep 17 00:00:00 2001
From: Nicholas42 <gcc@nicholas-schwab.de>
Date: Tue, 26 Jan 2021 21:57:57 +0100
Subject: [PATCH] Fixed constraints on operator<=>(optional<T>, U)

operator<=>(std::optional<_Tp>,_Up) was underconstrained. _Up needs to fulfill std::three_way_comparable<_Tp>. See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98842 and http://eel.is/c++draft/optional#comp.with.t-25.
---
 libstdc++-v3/include/std/optional | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

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; }