[libcxx-commits] [libcxx] [libc++] Extend __default_three_way_comparator to any types that only implements operator<=> (PR #157602)

[Louis Dionne via libcxx-commits]

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@@ -0,0 +1,36 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+
+#include <__utility/default_three_way_comparator.h>
+#include <string>
+#include <vector>
+
+static_assert(std::__has_default_three_way_comparator_v<int, int>);
+static_assert(std::__has_default_three_way_comparator_v<int, long>);
+static_assert(std::__has_default_three_way_comparator_v<long, int>);
+static_assert(std::__has_default_three_way_comparator_v<long, long>);
+static_assert(std::__has_default_three_way_comparator_v<std::string, std::string>);
+
+#if __has_builtin(__builtin_lt_synthesises_from_spaceship)
+static_assert(std::__has_default_three_way_comparator_v<const std::string&, const std::string&>);
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ldionne wrote:

This one can be taken out of the `#if` since we provide it even when the builtin isn't available.

https://github.com/llvm/llvm-project/pull/157602