Turn on -Wformat-nonliteral.

Apparently there are two classes of this warning in clang.
-Wformat-security is only emitted for cases of
`func(nonliteral_fmt_string)` (no args), and -Wformat-nonliteral is
emitted for cases *with* arguments. For whatever reason, the latter
isn't included in -Wextra and must be manually enabled.

To make this more easily portable to Windows, move the existing
gnu_printf/__printf__ decision into base/macros.h as ATTRIBUTE_FORMAT.

Change-Id: I3b0990e1d1f0a2e9c13b32f5cd60478946cb5fc6

2 files changed, 18 insertions, 19 deletions

diff --git a/base/include/base/macros.h b/base/include/base/macros.h
index b1ce7c6ba..35db83a09 100644
--- a/base/include/base/macros.h
+++ b/base/include/base/macros.h
@@ -185,4 +185,17 @@ void UNUSED(const T&...) {
   } while (0)
 #endif
 
+// These printf-like functions are implemented in terms of vsnprintf, so they
+// use the same attribute for compile-time format string checking. On Windows,
+// if the mingw version of vsnprintf is used, so use `gnu_printf' which allows z
+// in %zd and PRIu64 (and related) to be recognized by the compile-time
+// checking.
+#if defined(__USE_MINGW_ANSI_STDIO) && __USE_MINGW_ANSI_STDIO
+#define ATTRIBUTE_FORMAT(fmt, args) \
+  __attribute__((format(gnu_printf, fmt, args)))
+#else
+#define ATTRIBUTE_FORMAT(fmt, args) \
+  __attribute__((format(__printf__, fmt, args)))
+#endif
+
 #endif  // UTILS_MACROS_H
diff --git a/base/include/base/stringprintf.h b/base/include/base/stringprintf.h
index d68af8713..e17a2b521 100644
--- a/base/include/base/stringprintf.h
+++ b/base/include/base/stringprintf.h
@@ -20,35 +20,21 @@
 #include <stdarg.h>
 #include <string>
 
+#include "base/macros.h"
+
 namespace android {
 namespace base {
 
-// These printf-like functions are implemented in terms of vsnprintf, so they
-// use the same attribute for compile-time format string checking. On Windows,
-// if the mingw version of vsnprintf is used, use `gnu_printf' which allows z
-// in %zd and PRIu64 (and related) to be recognized by the compile-time
-// checking.
-#define FORMAT_ARCHETYPE __printf__
-#ifdef __USE_MINGW_ANSI_STDIO
-#if __USE_MINGW_ANSI_STDIO
-#undef FORMAT_ARCHETYPE
-#define FORMAT_ARCHETYPE gnu_printf
-#endif
-#endif
-
 // Returns a string corresponding to printf-like formatting of the arguments.
-std::string StringPrintf(const char* fmt, ...)
-    __attribute__((__format__(FORMAT_ARCHETYPE, 1, 2)));
+std::string StringPrintf(const char* fmt, ...) ATTRIBUTE_FORMAT(1, 2);
 
 // Appends a printf-like formatting of the arguments to 'dst'.
 void StringAppendF(std::string* dst, const char* fmt, ...)
-    __attribute__((__format__(FORMAT_ARCHETYPE, 2, 3)));
+    ATTRIBUTE_FORMAT(2, 3);
 
 // Appends a printf-like formatting of the arguments to 'dst'.
 void StringAppendV(std::string* dst, const char* format, va_list ap)
-    __attribute__((__format__(FORMAT_ARCHETYPE, 2, 0)));
-
-#undef FORMAT_ARCHETYPE
+    ATTRIBUTE_FORMAT(2, 0);
 
 }  // namespace base
 }  // namespace android