Implements RUN_ALL_TESTS() as a function.

include/gtest/gtest.h

@@ -2227,15 +2227,20 @@ bool StaticAssertTypeEq() {
   GTEST_TEST_(test_fixture, test_name, test_fixture, \
               ::testing::internal::GetTypeId<test_fixture>())
 
-// Use this macro in main() to run all tests.  It returns 0 if all
+}  // namespace testing
+
+// Use this function in main() to run all tests.  It returns 0 if all
 // tests are successful, or 1 otherwise.
 //
 // RUN_ALL_TESTS() should be invoked after the command line has been
 // parsed by InitGoogleTest().
+//
+// This function was formerly a macro; thus, it is in the global
+// namespace and has an all-caps name.
+int RUN_ALL_TESTS() GTEST_MUST_USE_RESULT_;
 
-#define RUN_ALL_TESTS()\
-  (::testing::UnitTest::GetInstance()->Run())
-
-}  // namespace testing
+inline int RUN_ALL_TESTS() {
+  return ::testing::UnitTest::GetInstance()->Run();
+}
 
 #endif  // GTEST_INCLUDE_GTEST_GTEST_H_