Removes an unused variable; also refactors to support an up-coming

googlemock change.

include/gtest/internal/gtest-internal.h

@@ -46,6 +46,10 @@
 # include <unistd.h>
 #endif  // GTEST_OS_LINUX
 
+#if GTEST_HAS_EXCEPTIONS
+# include <stdexcept>
+#endif
+
 #include <ctype.h>
 #include <string.h>
 #include <iomanip>
@@ -166,6 +170,21 @@ char (&IsNullLiteralHelper(...))[2];  // NOLINT
 GTEST_API_ std::string AppendUserMessage(
     const std::string& gtest_msg, const Message& user_msg);
 
+#if GTEST_HAS_EXCEPTIONS
+
+// This exception is thrown by (and only by) a failed Google Test
+// assertion when GTEST_FLAG(throw_on_failure) is true (if exceptions
+// are enabled).  We derive it from std::runtime_error, which is for
+// errors presumably detectable only at run time.  Since
+// std::runtime_error inherits from std::exception, many testing
+// frameworks know how to extract and print the message inside it.
+class GTEST_API_ GoogleTestFailureException : public ::std::runtime_error {
+ public:
+  explicit GoogleTestFailureException(const TestPartResult& failure);
+};
+
+#endif  // GTEST_HAS_EXCEPTIONS
+
 // A helper class for creating scoped traces in user programs.
 class GTEST_API_ ScopedTrace {
  public: