re PR c/39564 (variably modified function return types not always diagnosed)

	PR c/39564
	* c-decl.c (grokdeclarator): Diagnose declarations of functions
	with variably modified return type and no storage class
	specifiers, except for the case of nested functions.  Distinguish
	extern declarations of functions with variably modified return
	types from those of objects with variably modified types.

testsuite:
	* gcc.dg/vla-19.c: New test.

From-SVN: r146778

gcc/ChangeLog

+2009-04-25  Joseph Myers  <joseph@codesourcery.com>
+
+	PR c/39564
+	* c-decl.c (grokdeclarator): Diagnose declarations of functions
+	with variably modified return type and no storage class
+	specifiers, except for the case of nested functions.  Distinguish
+	extern declarations of functions with variably modified return
+	types from those of objects with variably modified types.
+
 2009-04-25  Jan Hubicka  <jh@suse.cz>
 
 	* tree.c (list_equal_p): New function.

gcc/c-decl.c

@@ -5012,11 +5012,17 @@ grokdeclarator (const struct c_declarator *declarator,
 	  DECL_TLS_MODEL (decl) = decl_default_tls_model (decl);
       }
 
-    if (storage_class == csc_extern
+    if ((storage_class == csc_extern
+	 || (storage_class == csc_none
+	     && TREE_CODE (type) == FUNCTION_TYPE
+	     && !funcdef_flag))
 	&& variably_modified_type_p (type, NULL_TREE))
       {
 	/* C99 6.7.5.2p2 */
-	error ("object with variably modified type must have no linkage");
+	if (TREE_CODE (type) == FUNCTION_TYPE)
+	  error ("non-nested function with variably modified type");
+	else
+	  error ("object with variably modified type must have no linkage");
       }
 
     /* Record `register' declaration for warnings on &

gcc/testsuite/ChangeLog

 2009-04-25  Joseph Myers  <joseph@codesourcery.com>
 
+	PR c/39564
+	* gcc.dg/vla-19.c: New test.
+
+2009-04-25  Joseph Myers  <joseph@codesourcery.com>
+
 	PR preprocessor/39559
 	* gcc.dg/c99-intconst-2.c: New test.
 

gcc/testsuite/gcc.dg/vla-19.c

+/* Test diagnostics for variably modified function return types.  PR
+   39564.  */
+/* { dg-do compile } */
+/* { dg-options "-std=c99" } */
+
+int a;
+
+void
+f1 (void)
+{
+  typedef int T[a];
+  extern T *g1 (void); /* { dg-error "non-nested function with variably modified type" } */
+}
+
+void
+f2 (void)
+{
+  extern int (*g2 (void))[a]; /* { dg-error "non-nested function with variably modified type" } */
+}
+
+void
+f3 (void)
+{
+  typedef int T[a];
+  T *g3 (void); /* { dg-error "non-nested function with variably modified type" } */
+}
+
+void
+f4 (void)
+{
+  int (*g4 (void))[a]; /* { dg-error "non-nested function with variably modified type" } */
+}