Adds CHECK support for nullptr. (fixes google#341)

This allows CHECK_NE(foo, nullptr) to compile and produces "nullptr" for the
string representation of nullptr.

CONTRIBUTORS

@@ -26,6 +26,7 @@ Abhishek Dasgupta <abhi2743@gmail.com>
 Abhishek Parmar <abhishek@orng.net>
 Andrew Schwartzmeyer <andrew@schwartzmeyer.com>
 Andy Ying <andy@trailofbits.com>
+Bret McKee <bretmckee@google.com>
 Brian Silverman <bsilver16384@gmail.com>
 Fumitoshi Ukai <ukai@google.com>
 Guillaume Dumont <dumont.guillaume@gmail.com>

src/glog/logging.h.in

@@ -649,6 +649,10 @@ void MakeCheckOpValueString(std::ostream* os, const signed char& v);
 template <> GOOGLE_GLOG_DLL_DECL
 void MakeCheckOpValueString(std::ostream* os, const unsigned char& v);
 
+// Provide printable value for nullptr_t
+template <> GOOGLE_GLOG_DLL_DECL
+void MakeCheckOpValueString(std::ostream* os, const std::nullptr_t& v);
+
 // Build the error message string. Specify no inlining for code size.
 template <typename T1, typename T2>
 std::string* MakeCheckOpString(const T1& v1, const T2& v2, const char* exprtext)

src/logging.cc

@@ -2163,6 +2163,11 @@ void MakeCheckOpValueString(std::ostream* os, const unsigned char& v) {
   }
 }
 
+template <>
+void MakeCheckOpValueString(std::ostream* os, const std::nullptr_t& v) {
+  (*os) << "nullptr";
+}
+
 void InitGoogleLogging(const char* argv0) {
   glog_internal_namespace_::InitGoogleLoggingUtilities(argv0);
 }