_synctex_error has a printf-like format, so use the proper gcc extensions
to check its arguments (doing nothing for other compilers)
Author: Pino Toscano <pino@kde.org>

Index: synctex/synctex_parser_utils.h
===================================================================
--- synctex.orig/synctex_parser_utils.h
+++ synctex/synctex_parser_utils.h
@@ -83,6 +83,12 @@ extern "C" {
 #	else
 #		define SYNCTEX_ARE_PATH_CHARACTERS_EQUAL(left,right) (toupper(left) != toupper(right))
 #	endif
+
+#	ifdef __GNUC__
+#		define SYNCTEX_PRINTF_FORMAT(si, ftc) __attribute__ ((format (printf, si, ftc)))
+#	else
+#		define SYNCTEX_PRINTF_FORMAT(si, ftc)
+#	endif
     
 /*  This custom malloc functions initializes to 0 the newly allocated memory.
  *  There is no bzero function on windows. */
@@ -95,8 +101,8 @@ void _synctex_free(void * ptr);
 /*  This is used to log some informational message to the standard error stream.
  *  On Windows, the stderr stream is not exposed and another method is used.
  *	The return value is the number of characters printed.	*/
-    int _synctex_error(const char * reason,...);
-    int _synctex_debug(const char * reason,...);
+    int _synctex_error(const char * reason,...) SYNCTEX_PRINTF_FORMAT(1, 2);
+    int _synctex_debug(const char * reason,...) SYNCTEX_PRINTF_FORMAT(1, 2);
 
 /*  strip the last extension of the given string, this string is modified!
  *  This function depends on the OS because the path separator may differ.
Index: synctex/synctex_parser.c
===================================================================
--- synctex.orig/synctex_parser.c
+++ synctex/synctex_parser.c
@@ -8148,6 +8148,7 @@ struct synctex_updater_t {
     int length;             /*  the number of chars appended */
 };
 
+static int _synctex_updater_print(synctex_updater_p updater, const char * format, ...) SYNCTEX_PRINTF_FORMAT(2, 3);
 static int _synctex_updater_print(synctex_updater_p updater, const char * format, ...) {
     int result = 0;
     if (updater) {
@@ -8184,6 +8185,7 @@ static int vasprintf(char **ret,
 /**
  *  gzvprintf is not available until OSX 10.10
  */
+static int _synctex_updater_print_gz(synctex_updater_p updater, const char * format, ...) SYNCTEX_PRINTF_FORMAT(2, 3);
 static int _synctex_updater_print_gz(synctex_updater_p updater, const char * format, ...) {
     int result = 0;
     if (updater) {
Index: synctex/synctex_parser_utils.c
===================================================================
--- synctex.orig/synctex_parser_utils.c
+++ synctex/synctex_parser_utils.c
@@ -87,8 +87,11 @@ void _synctex_free(void * ptr) {
 #   include <syslog.h>
 #endif
 
-int _synctex_log(int level, const char * prompt, const char * reason, va_list arg;) {
+int _synctex_log(int level, const char * prompt, const char * reason, ...) SYNCTEX_PRINTF_FORMAT(3, 4);
+int _synctex_log(int level, const char * prompt, const char * reason, ...) {
+    va_list arg;
 	int result;
+    va_start(arg, reason);
 #	ifdef SYNCTEX_RECENT_WINDOWS
 	{/*	This code is contributed by William Blum.
         As it does not work on some older computers,
@@ -130,6 +133,7 @@ int _synctex_log(int level, const char *
     result += vfprintf(where, reason, arg);
     result += fprintf(where,"\n");
 #   endif
+    va_end(arg);
 	return result;
 }