[libcxx-commits] [libcxx] [libc++] Implement P3379R0 Constrain `std::expected` equality operators (PR #135759)

[Hristo Hristov via libcxx-commits]

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@@ -1139,8 +1140,12 @@ class expected : private __expected_base<_Tp, _Err> {
 
   // [expected.object.eq], equality operators
   template <class _T2, class _E2>
-    requires(!is_void_v<_T2>)
-  _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const expected& __x, const expected<_T2, _E2>& __y) {
+  _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const expected& __x, const expected<_T2, _E2>& __y)
+    requires(!is_void_v<_T2>) && requires {
+      { *__x == *__y } -> __boolean_testable;
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H-G-Hristov wrote:

@frederick-vs-ja I think I can update reference_wrapper soon but I'll use boolean testable for pair as the standard tells. As I don't feel there is a consensus on backporting the constraints I won't apply them as DR for now. It can be done later. WDYT?

https://github.com/llvm/llvm-project/pull/135759