Fix snprintf()/vsnprintf() -Wformat vs. multiple definition issue.

diff --git a/mingwrt/ChangeLog b/mingwrt/ChangeLog
index e3f2881..2765231 100644 (file)
--- a/mingwrt/ChangeLog
+++ b/mingwrt/ChangeLog
@@ -1,3 +1,25 @@
+2017-05-24  Keith Marshall  <keithmarshall@users.sourceforge.net>
+
+       Fix snprintf()/vsnprintf() -Wformat vs. multiple definition issue.
+
+       * include/stdio.h (__mingw_stdio_redirect__): Add reference to...
+       (__Wformat): ...this new macro; define it, such that it expands via...
+       (__Wformat_mingw_printf, __Wformat_msvcrt_printf): ...these new macros,
+       ultimately expanding to an attribute declaration, in terms of...
+       (__Wformat_ms_vprintf, __Wformat_ms_vfprintf, __Wformat_ms_vsprintf)
+       (__Wformat_ms_printf, __Wformat_ms_fprintf, __Wformat_ms_sprintf):
+       ...any one of these; they map to an ms_printf attribute, or...
+       (__Wformat_vprintf, __Wformat_vfprintf, __Wformat_vsprintf)
+       (__Wformat_printf, __Wformat_fprintf, __Wformat_sprintf): ...any one
+       of these; they map conditionally to...
+       [__GNUC__>=6] (__mingw_printf__): ...this new format attribute, or...
+       [__GNUC__< 6]: ...nothing.
+       (snprintf, vsnprintf): Revert 2017-01-30 inline definitions; add...
+       (__Wformat_snprintf, __Wformat_vsnprintf): ...these attributes; they
+       are also mapped conditionally, in this case to...
+       [__GNUC__>=6] (__mingw_printf__): ...this, or...
+       [__GNUC__< 6] (__gnu_printf__): ...this.
+
 2017-03-14  Keith Marshall  <keithmarshall@users.sourceforge.net>
 
        Refactor mingwrt and w32api common makefile content.

diff --git a/mingwrt/include/stdio.h b/mingwrt/include/stdio.h
index e17afa0..ab03057 100644 (file)
--- a/mingwrt/include/stdio.h
+++ b/mingwrt/include/stdio.h
@@ -298,10 +298,46 @@ _CRTIMP __cdecl __MINGW_NOTHROW  void   setbuf (FILE *, char *);
 /* Formatted Output
  *
  * MSVCRT implementations are not ANSI C99 conformant...
- * we offer these conforming alternatives from libmingwex.a
+ * we offer conforming alternatives from libmingwex.a
  */
 #undef  __mingw_stdio_redirect__
-#define __mingw_stdio_redirect__(F) __cdecl __MINGW_NOTHROW __mingw_##F
+#define __mingw_stdio_redirect__(F) __cdecl __MINGW_NOTHROW __Wformat(F)
+#define __Wformat_mingw_printf(F,A) __attribute__((__format__(__mingw_printf__,F,A)))
+
+#if __GNUC__ >= 6
+/* From GCC-6 onwards, we will provide customized -Wformat
+ * handling, via our own mingw_printf format category...
+ */
+#define __Wformat(F)           __Wformat_##F __mingw_##F
+
+#else  /* __GNUC__ < 6 */
+/* ...whereas, for earlier GCC, we preserve the status quo,
+ * offering no -Wformat checking for those functions which
+ * replace the MSVCRT.DLL versions...
+ */
+#define __Wformat(F)           __mingw_##F
+/*
+ * ...while degrading to gnu_printf checking for snprintf()
+ * and vsnprintf(), (which are ALWAYS MinGW.org variants).
+ */
+#define __mingw_printf__       __gnu_printf__
+#endif
+
+/* The following convenience macros specify the appropriate
+ * -Wformat checking for MSVCRT.DLL replacement functions...
+ */
+#define __Wformat_printf       __Wformat_mingw_printf(1,2)
+#define __Wformat_fprintf      __Wformat_mingw_printf(2,3)
+#define __Wformat_sprintf      __Wformat_mingw_printf(2,3)
+#define __Wformat_vprintf      __Wformat_mingw_printf(1,0)
+#define __Wformat_vfprintf     __Wformat_mingw_printf(2,0)
+#define __Wformat_vsprintf     __Wformat_mingw_printf(2,0)
+/*
+ * ...while this pair are specific to the two MinGW.org
+ * only functions.
+ */
+#define __Wformat_snprintf     __Wformat_mingw_printf(3,4)
+#define __Wformat_vsnprintf    __Wformat_mingw_printf(3,0)
 
 extern int __mingw_stdio_redirect__(fprintf)(FILE*, const char*, ...);
 extern int __mingw_stdio_redirect__(printf)(const char*, ...);
@@ -394,16 +430,6 @@ int sprintf (char *__stream, const char *__format, ...)
 }
 
 __mingw_stdio_redirect__
-int snprintf (char *__stream, size_t __len, const char *__format, ...)
-{
-  register int __retval;
-  __builtin_va_list __local_argv; __builtin_va_start( __local_argv, __format );
-  __retval = __mingw_vsnprintf( __stream, __len, __format, __local_argv );
-  __builtin_va_end( __local_argv );
-  return __retval;
-}
-
-__mingw_stdio_redirect__
 int vfprintf (FILE *__stream, const char *__format, __VALIST __local_argv)
 {
   return __mingw_vfprintf( __stream, __format, __local_argv );
@@ -421,13 +447,7 @@ int vsprintf (char *__stream, const char *__format, __VALIST __local_argv)
   return __mingw_vsprintf( __stream, __format, __local_argv );
 }
 
-__mingw_stdio_redirect__
-int vsnprintf (char *__stream, size_t __len, const char *__format, __VALIST __local_argv)
-{
-  return __mingw_vsnprintf( __stream, __len, __format, __local_argv );
-}
-
-#else
+#else  /* !__USE_MINGW_ANSI_STDIO */
 /* Default configuration: simply direct all calls to MSVCRT...
  */
 _CRTIMP __cdecl __MINGW_NOTHROW  int fprintf (FILE *, const char *, ...);
@@ -439,10 +459,21 @@ _CRTIMP __cdecl __MINGW_NOTHROW  int vsprintf (char *, const char *, __VALIST);
 
 #endif
 /* Regardless of user preference, always offer these alternative
- * entry points, for direct access to the MSVCRT implementations.
+ * entry points, for direct access to the MSVCRT implementations,
+ * with ms_printf -Wformat checking in each case.
  */
+#undef  __Wformat
 #undef  __mingw_stdio_redirect__
-#define __mingw_stdio_redirect__(F) __cdecl __MINGW_NOTHROW __msvcrt_##F
+#define __mingw_stdio_redirect__(F) __cdecl __MINGW_NOTHROW __Wformat(F)
+#define __Wformat_msvcrt_printf(F,A) __attribute__((__format__(__ms_printf__,F,A)))
+#define __Wformat(F) __Wformat_ms_##F __msvcrt_##F
+
+#define __Wformat_ms_printf    __Wformat_msvcrt_printf(1,2)
+#define __Wformat_ms_fprintf   __Wformat_msvcrt_printf(2,3)
+#define __Wformat_ms_sprintf   __Wformat_msvcrt_printf(2,3)
+#define __Wformat_ms_vprintf   __Wformat_msvcrt_printf(1,0)
+#define __Wformat_ms_vfprintf  __Wformat_msvcrt_printf(2,0)
+#define __Wformat_ms_vsprintf  __Wformat_msvcrt_printf(2,0)
 
 _CRTIMP int __mingw_stdio_redirect__(fprintf)(FILE *, const char *, ...);
 _CRTIMP int __mingw_stdio_redirect__(printf)(const char *, ...);
@@ -452,6 +483,7 @@ _CRTIMP int __mingw_stdio_redirect__(vprintf)(const char *, __VALIST);
 _CRTIMP int __mingw_stdio_redirect__(vsprintf)(char *, const char *, __VALIST);
 
 #undef  __mingw_stdio_redirect__
+#undef  __Wformat
 
 /* The following three ALWAYS refer to the MSVCRT implementations...
  */
@@ -466,10 +498,14 @@ _CRTIMP __cdecl __MINGW_NOTHROW  int _vscprintf (const char *, __VALIST);
  * NOT compatible with C99, but the following are; if you want the
  * MSVCRT behaviour, you MUST use the Microsoft "uglified" names.
  */
-__cdecl __MINGW_NOTHROW  int snprintf (char *, size_t, const char *, ...);
-__cdecl __MINGW_NOTHROW  int vsnprintf (char *, size_t, const char *, __VALIST);
+__cdecl __MINGW_NOTHROW __Wformat_snprintf
+int snprintf (char *, size_t, const char *, ...);
+
+__cdecl __MINGW_NOTHROW __Wformat_vsnprintf
+int vsnprintf (char *, size_t, const char *, __VALIST);
 
-__cdecl __MINGW_NOTHROW  int vscanf (const char * __restrict__, __VALIST);
+__cdecl __MINGW_NOTHROW
+int vscanf (const char * __restrict__, __VALIST);
 
 __cdecl __MINGW_NOTHROW
 int vfscanf (FILE * __restrict__, const char * __restrict__, __VALIST);