1 files changed, 64 insertions, 0 deletions
diff --git a/libstdc++-v3/testsuite/20_util/expected/lwg3877.cc b/libstdc++-v3/testsuite/20_util/expected/lwg3877.cc
new file mode 100644
index 00000000000..556d8d5dc9e
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/expected/lwg3877.cc
@@ -0,0 +1,64 @@
+// { dg-options "-std=gnu++23" }
+// { dg-do compile { target c++23 } }
+
+#include <expected>
+
+struct T1
+{
+};
+
+struct T2
+{
+  T2(const T2&) = delete;
+};
+
+struct T3
+{
+  T3(const T3&) = delete;
+  T3(T3&&) = delete;
+  T3(T3&) { }
+  T3(const T3&&) { }
+};
+
+template<typename Exp, typename F>
+concept Has_or_else = requires(Exp&& exp, F f) {
+  std::forward<Exp>(exp).or_else(f);
+};
+
+using E1 = std::expected<T1, int>;
+static_assert( Has_or_else<E1&, E1(int)> );
+static_assert( Has_or_else<const E1&, E1(int)> );
+static_assert( Has_or_else<E1&&, E1(int)> );
+static_assert( Has_or_else<const E1&&, E1(int)> );
+
+using E2 = std::expected<T2, int>;
+static_assert( !Has_or_else<E2&, E2(int)> );
+static_assert( !Has_or_else<const E2&, E2(int)> );
+static_assert( !Has_or_else<E2&&, E2(int)> );
+static_assert( !Has_or_else<const E2&&, E2(int)> );
+
+using E3 = std::expected<T3, int>;
+static_assert( Has_or_else<E3&, E3(int)> );
+static_assert( !Has_or_else<const E3&, E3(int)> );
+static_assert( Has_or_else<E3&&, E3(int)> ); // uses or_else(F) const &&
+static_assert( Has_or_else<const E3&&, E3(int)> );
+
+template<typename Exp, typename F>
+concept Has_transform_error = requires(Exp&& exp, F f) {
+  std::forward<Exp>(exp).transform_error(f);
+};
+
+static_assert( Has_transform_error<E1&, int(int)> );
+static_assert( Has_transform_error<const E1&, int(int)> );
+static_assert( Has_transform_error<E1&&, int(int)> );
+static_assert( Has_transform_error<const E1&&, int(int)> );
+
+static_assert( !Has_transform_error<E2&, int(int)> );
+static_assert( !Has_transform_error<const E2&, int(int)> );
+static_assert( !Has_transform_error<E2&&, int(int)> );
+static_assert( !Has_transform_error<const E2&&, int(int)> );
+
+static_assert( Has_transform_error<E3&, int(int)> );
+static_assert( !Has_transform_error<const E3&, int(int)> );
+static_assert( Has_transform_error<E3&&, int(int)> ); // uses transform_error(F) const &&
+static_assert( Has_transform_error<const E3&&, int(int)> );