Implement P0768r1: Library support for the Spaceship Operator.

this patch adds the <compare> header and implements all of it
except for [comp.alg].

As I understand it, the header is needed by the compiler in
when implementing the semantics of operator<=>. For that reason
I feel it's important to land this header early, despite
all compilers lacking support.

llvm-svn: 329460

1 files changed, 70 insertions, 0 deletions

diff --git a/libcxx/test/std/language.support/cmp/cmp.weakeq/cmp.weakeq.pass.cpp b/libcxx/test/std/language.support/cmp/cmp.weakeq/cmp.weakeq.pass.cpp
new file mode 100644
index 00000000000..375cff460cd
--- /dev/null
+++ b/libcxx/test/std/language.support/cmp/cmp.weakeq/cmp.weakeq.pass.cpp
@@ -0,0 +1,70 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
+
+// <compare>
+
+// class weak_equality
+
+
+#include <compare>
+#include <cassert>
+#include "test_macros.h"
+
+const volatile void* volatile sink;
+
+void test_static_members() {
+  DoNotOptimize(&std::weak_equality::equivalent);
+  DoNotOptimize(&std::weak_equality::nonequivalent);
+}
+
+void test_signatures() {
+  auto& Eq = std::weak_equality::equivalent;
+
+  ASSERT_NOEXCEPT(Eq == 0);
+  ASSERT_NOEXCEPT(0 == Eq);
+  ASSERT_NOEXCEPT(Eq != 0);
+  ASSERT_NOEXCEPT(0 != Eq);
+#ifndef TEST_HAS_NO_SPACESHIP_OPERATOR
+  ASSERT_NOEXCEPT(0 <=> Eq);
+  ASSERT_NOEXCEPT(Eq <=> 0);
+  ASSERT_SAME_TYPE(decltype(Eq <=> 0), std::weak_equality);
+  ASSERT_SAME_TYPE(decltype(0 <=> Eq), std::weak_equality);
+#endif
+}
+
+constexpr bool test_constexpr() {
+  auto& Eq = std::weak_equality::equivalent;
+  auto& NEq = std::weak_equality::nonequivalent;
+  assert((Eq == 0) == true);
+  assert((0 == Eq) == true);
+  assert((NEq == 0) == false);
+  assert((0 == NEq) == false);
+
+  assert((Eq != 0) == false);
+  assert((0 != Eq) == false);
+  assert((NEq != 0) == true);
+  assert((0 != NEq) == true);
+
+#ifndef TEST_HAS_NO_SPACESHIP_OPERATOR
+  std::weak_equality res = (Eq <=> 0);
+  ((void)res);
+  res = (0 <=> Eq);
+  ((void)res);
+#endif
+
+  return true;
+}
+
+int main() {
+  test_static_members();
+  test_signatures();
+  static_assert(test_constexpr(), "constexpr test failed");
+}