Mojo: Split off the C++ parts of mojo/public/c/system macros.h to their own file.

mojo/public/c/tests/system/macros_unittest.cc

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// This file tests the C Mojo system macros and consists of "positive" tests,
+// i.e., those verifying that things work (without compile errors, or even
+// warnings if warnings are treated as errors).
+// TODO(vtl): Fix no-compile tests (which are all disabled; crbug.com/105388)
+// and write some "negative" tests.
+
+#include "mojo/public/c/system/macros.h"
+
+#include <assert.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace mojo {
+namespace {
+
+TEST(MacrosTest, AllowUnused) {
+  // Test that no warning/error is issued even though |x| is unused.
+  int x MOJO_ALLOW_UNUSED = 123;
+}
+
+int MustUseReturnedResult() MOJO_WARN_UNUSED_RESULT;
+int MustUseReturnedResult() {
+  return 456;
+}
+
+TEST(MacrosTest, WarnUnusedResult) {
+  if (!MustUseReturnedResult())
+    abort();
+}
+
+// First test |MOJO_COMPILE_ASSERT()| in a global scope.
+MOJO_COMPILE_ASSERT(sizeof(int64_t) == 2 * sizeof(int32_t),
+                    bad_compile_assert_failure_in_global_scope);
+
+TEST(MacrosTest, CompileAssert) {
+  // Then in a local scope.
+  MOJO_COMPILE_ASSERT(sizeof(int32_t) == 2 * sizeof(int16_t),
+                      bad_compile_assert_failure);
+}
+
+}  // namespace
+}  // namespace mojo