c-decl.c (diagnose_mismatched_decls): Give an error for redefining a typedef with variably modified type.

* c-decl.c (diagnose_mismatched_decls): Give an error for
	redefining a typedef with variably modified type.

testsuite:
	* gcc.dg/c1x-typedef-1.c: Expect errors for redefinitions of
	variably modified typedefs.
	* gcc.dg/c1x-typedef-2.c: Remove.

From-SVN: r171172

gcc/ChangeLog

@@ -1,3 +1,8 @@
+2011-03-18  Joseph Myers  <joseph@codesourcery.com>
+
+	* c-decl.c (diagnose_mismatched_decls): Give an error for
+	redefining a typedef with variably modified type.
+
 2011-03-18  Joseph Myers  <joseph@codesourcery.com>
 
 	* c-decl.c (grokfield): Don't allow typedefs for structures or

gcc/c-decl.c

@@ -1813,22 +1813,18 @@ diagnose_mismatched_decls (tree newdecl, tree olddecl,
 	  || TREE_NO_WARNING (olddecl))
 	return true;  /* Allow OLDDECL to continue in use.  */
 
-      if (pedantic && !flag_isoc1x)
+      if (variably_modified_type_p (newtype, NULL))
+	{
+	  error ("redefinition of typedef %q+D with variably modified type",
+		 newdecl);
+	  locate_old_decl (olddecl);
+	}
+      else if (pedantic && !flag_isoc1x)
 	{
 	  pedwarn (input_location, OPT_pedantic,
 		   "redefinition of typedef %q+D", newdecl);
 	  locate_old_decl (olddecl);
 	}
-      else if (variably_modified_type_p (newtype, NULL))
-	{
-	  /* Whether there is a constraint violation for the types not
-	     being the same cannot be determined at compile time; a
-	     warning that there may be one at runtime is considered
-	     appropriate (WG14 reflector message 11743, 8 May 2009).  */
-	  warning (0, "redefinition of typedef %q+D may be a constraint "
-		   "violation at runtime", newdecl);
-	  locate_old_decl (olddecl);
-	}
 
       return true;
     }

gcc/testsuite/ChangeLog

@@ -1,3 +1,9 @@
+2011-03-18  Joseph Myers  <joseph@codesourcery.com>
+
+	* gcc.dg/c1x-typedef-1.c: Expect errors for redefinitions of
+	variably modified typedefs.
+	* gcc.dg/c1x-typedef-2.c: Remove.
+
 2011-03-18  Joseph Myers  <joseph@codesourcery.com>
 
 	* gcc.dg/c1x-anon-struct-1.c: Don't test use of typedefs.

gcc/testsuite/gcc.dg/c1x-typedef-1.c

@@ -3,7 +3,8 @@
 /* { dg-options "-std=c1x -pedantic-errors" } */
 
 /* C1X permits typedefs to be redeclared to the same type, but not to
-   different-but-compatible types.  */
+   different-but-compatible types, and not when the type is variably
+   modified.  */
 
 #include <limits.h>
 
@@ -60,9 +61,10 @@ f (void)
   typedef void FN2(int (*p)[*]); /* { dg-message "previous declaration" } */
   typedef void FN2(int (*p)[]); /* { dg-error "with different type" } */
   typedef int AV[a]; /* { dg-message "previous declaration" } */
-  typedef int AV[b-1]; /* { dg-warning "may be a constraint violation at runtime" } */
+  typedef int AV[b-1]; /* { dg-error "redefinition" } */
-  typedef int AAa[a];
+  typedef int AAa[a]; /* { dg-message "previous declaration" } */
   typedef int AAb[b-1];
   typedef AAa *VF(void); /* { dg-message "previous declaration" } */
-  typedef AAb *VF(void); /* { dg-warning "may be a constraint violation at runtime" } */
+  typedef AAb *VF(void); /* { dg-error "redefinition" } */
+  typedef AAa AAa; /* { dg-error "redefinition" } */
 }

gcc/testsuite/gcc.dg/c1x-typedef-2.c

@@ -1,18 +0,0 @@
-/* Test typedef redeclaration in C1X.  Side effects from duplicate
-   declarations still apply.  */
-/* { dg-do run } */
-/* { dg-options "-std=c1x -pedantic-errors" } */
-
-extern void exit (int);
-extern void abort (void);
-
-int
-main (void)
-{
-  int a = 1, b = 1;
-  typedef int T[++a]; /* { dg-message "previous declaration" } */
-  typedef int T[++b]; /* { dg-warning "may be a constraint violation at runtime" } */
-  if (a != 2 || b != 2)
-    abort ();
-  exit (0);
-}