[libcxx-commits] [libcxx] [libc++] Resolve LWG4370 (PR #174062)

[A. Jiang via libcxx-commits]

================
@@ -0,0 +1,42 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++17
+// <optional>
+
+// Verify that example provided for LWG4370 compiles.
+
+#include <cassert>
+#include <optional>
+
+struct Bool {
+  Bool(bool) {};
+  operator bool() const { return true; };
+};
+
+struct S {
+  Bool operator==(S) const { return true; }
+  Bool operator!=(S) const { return true; }
+  Bool operator<=(S) const { return true; }
+  Bool operator<(S) const { return true; }
+  Bool operator>(S) const { return true; }
+  Bool operator>=(S) const { return true; }
+};
+
+int main() {
+  std::optional<S> s{S{}};
+
+  (void)(s == S{});
+  (void)(s != S{});
+  (void)(s < S{});
+  (void)(s > S{});
+  (void)(s <= S{});
+  (void)(s >= S{});
----------------
frederick-vs-ja wrote:

If you want to run this test, IMO, comparison involving valueless `optional` should also be tested.

https://github.com/llvm/llvm-project/pull/174062