Add check for the PyArg_ParseTuple format, and declare

it if it is supported.

Include/modsupport.h

@@ -24,7 +24,7 @@ PyAPI_FUNC(PyObject *) _Py_VaBuildValue_SizeT(const char *, va_list);
 #endif
 
 PyAPI_FUNC(int) PyArg_Parse(PyObject *, const char *, ...);
-PyAPI_FUNC(int) PyArg_ParseTuple(PyObject *, const char *, ...);
+PyAPI_FUNC(int) PyArg_ParseTuple(PyObject *, const char *, ...) Py_FORMAT_PARSETUPLE(PyArg_ParseTuple, 2, 3);
 PyAPI_FUNC(int) PyArg_ParseTupleAndKeywords(PyObject *, PyObject *,
                                                   const char *, char **, ...);
 PyAPI_FUNC(int) PyArg_UnpackTuple(PyObject *, const char *, Py_ssize_t, Py_ssize_t, ...);

Include/pyport.h

@@ -749,6 +749,15 @@ typedef	struct fd_set {
 #define Py_GCC_ATTRIBUTE(x) __attribute__(x)
 #endif
 
+/*
+ * Add PyArg_ParseTuple format where available.
+ */
+#ifdef HAVE_ATTRIBUTE_FORMAT_PARSETUPLE
+#define Py_FORMAT_PARSETUPLE(func,p1,p2) __attribute__((format(func,p1,p2)))
+#else
+#define Py_FORMAT_PARSETUPLE(func,p1,p2)
+#endif
+
 /* Eliminate end-of-loop code not reached warnings from SunPro C
  * when using do{...}while(0) macros
  */

Misc/NEWS

@@ -223,6 +223,9 @@ Tools
 Build
 -----
 
+- configure now checks whether gcc supports the PyArg_ParseTuple format
+  attribute.
+
 - Bug #1578513: Cross compilation was broken by a change to configure. 
   Repair so that it's back to how it was in 2.4.3.
 

configure

 #! /bin/sh
-# From configure.in Revision: 52089 .
+# From configure.in Revision: 52363 .
 # Guess values for system-dependent variables and create Makefiles.
 # Generated by GNU Autoconf 2.59 for python 2.6.
 #
@@ -4036,6 +4036,70 @@ echo "${ECHO_T}$ac_cv_olimit_ok" >&6
   fi
 fi
 
+# Check whether GCC supports PyArg_ParseTuple format
+if test "$GCC" = "yes"
+then
+  echo "$as_me:$LINENO: checking whether gcc supports ParseTuple __format__" >&5
+echo $ECHO_N "checking whether gcc supports ParseTuple __format__... $ECHO_C" >&6
+  save_CFLAGS=$CFLAGS
+  CFLAGS="$CFLAGS -Werror"
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+    void f(char*,...)__attribute((format(PyArg_ParseTuple, 1, 2)));
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
+  (eval $ac_compile) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_ATTRIBUTE_FORMAT_PARSETUPLE 1
+_ACEOF
+
+  echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6
+
+fi
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+
 # On some compilers, pthreads are available without further options
 # (e.g. MacOS X). On some of these systems, the compiler will not
 # complain if unaccepted options are passed (e.g. gcc on Mac OS X).

configure.in

@@ -890,6 +890,21 @@ else
   fi
 fi
 
+# Check whether GCC supports PyArg_ParseTuple format
+if test "$GCC" = "yes"
+then
+  AC_MSG_CHECKING(whether gcc supports ParseTuple __format__)
+  save_CFLAGS=$CFLAGS
+  CFLAGS="$CFLAGS -Werror"
+  AC_TRY_COMPILE([
+    void f(char*,...)__attribute((format(PyArg_ParseTuple, 1, 2)));
+  ],,
+  AC_DEFINE(HAVE_ATTRIBUTE_FORMAT_PARSETUPLE, 1, [Define if GCC supports __attribute__((format(PyArg_ParseTuple, 2, 3)))])
+  AC_MSG_RESULT(yes),
+  AC_MSG_RESULT(no)
+  )
+fi
+
 # On some compilers, pthreads are available without further options
 # (e.g. MacOS X). On some of these systems, the compiler will not
 # complain if unaccepted options are passed (e.g. gcc on Mac OS X).

pyconfig.h.in

@@ -40,6 +40,9 @@
 /* Define to 1 if you have the <asm/types.h> header file. */
 #undef HAVE_ASM_TYPES_H
 
+/* Define if GCC supports __attribute__((format(PyArg_ParseTuple, 2, 3))) */
+#undef HAVE_ATTRIBUTE_FORMAT_PARSETUPLE
+
 /* Define to 1 if you have the `bind_textdomain_codeset' function. */
 #undef HAVE_BIND_TEXTDOMAIN_CODESET