Annotate ColoredPrintf with the format attribute and fix bugs.

googletest doesn't currently build with clang's very aggressive
-Wformat-nonliteral warning. It requires that all non-literal format
strings come from the argument of a function annotated with a compatible
format attribute.

Fixing that reports that ColoredPrintf's callers weren't passing the
normal -Wformat warning. Some messages were passed directly into the
format string rather than via "%s".

googletest/include/gtest/internal/gtest-port.h

@@ -874,6 +874,23 @@ using ::std::tuple_size;
 # define GTEST_ATTRIBUTE_UNUSED_
 #endif
 
+// Use this annotation before a function that takes a printf format string.
+#if defined(__GNUC__) && !defined(COMPILER_ICC)
+# if defined(__MINGW_PRINTF_FORMAT)
+// MinGW has two different printf implementations. Ensure the format macro
+// matches the selected implementation. See
+// https://sourceforge.net/p/mingw-w64/wiki2/gnu%20printf/.
+#  define GTEST_ATTRIBUTE_PRINTF_(string_index, first_to_check) \
+       __attribute__((__format__(__MINGW_PRINTF_FORMAT, string_index, \
+                                 first_to_check)))
+# else
+#  define GTEST_ATTRIBUTE_PRINTF_(string_index, first_to_check) \
+       __attribute__((__format__(__printf__, string_index, first_to_check)))
+# endif
+#else
+# define GTEST_ATTRIBUTE_PRINTF_(string_index, first_to_check)
+#endif
+
 // A macro to disallow operator=
 // This should be used in the private: declarations for a class.
 #define GTEST_DISALLOW_ASSIGN_(type)\

googletest/src/gtest.cc

@@ -2953,6 +2953,7 @@ bool ShouldUseColor(bool stdout_is_tty) {
 // cannot simply emit special characters and have the terminal change colors.
 // This routine must actually emit the characters rather than return a string
 // that would be colored when printed, as can be done on Linux.
+GTEST_ATTRIBUTE_PRINTF_(2, 3)
 void ColoredPrintf(GTestColor color, const char* fmt, ...) {
   va_list args;
   va_start(args, fmt);
@@ -4729,7 +4730,7 @@ bool ShouldShard(const char* total_shards_env,
       << "Invalid environment variables: you have "
       << kTestShardIndex << " = " << shard_index
       << ", but have left " << kTestTotalShards << " unset.\n";
-    ColoredPrintf(COLOR_RED, msg.GetString().c_str());
+    ColoredPrintf(COLOR_RED, "%s", msg.GetString().c_str());
     fflush(stdout);
     exit(EXIT_FAILURE);
   } else if (total_shards != -1 && shard_index == -1) {
@@ -4737,7 +4738,7 @@ bool ShouldShard(const char* total_shards_env,
       << "Invalid environment variables: you have "
       << kTestTotalShards << " = " << total_shards
       << ", but have left " << kTestShardIndex << " unset.\n";
-    ColoredPrintf(COLOR_RED, msg.GetString().c_str());
+    ColoredPrintf(COLOR_RED, "%s", msg.GetString().c_str());
     fflush(stdout);
     exit(EXIT_FAILURE);
   } else if (shard_index < 0 || shard_index >= total_shards) {
@@ -4746,7 +4747,7 @@ bool ShouldShard(const char* total_shards_env,
       << kTestShardIndex << " < " << kTestTotalShards
       << ", but you have " << kTestShardIndex << "=" << shard_index
       << ", " << kTestTotalShards << "=" << total_shards << ".\n";
-    ColoredPrintf(COLOR_RED, msg.GetString().c_str());
+    ColoredPrintf(COLOR_RED, "%s", msg.GetString().c_str());
     fflush(stdout);
     exit(EXIT_FAILURE);
   }