[backport from gcc-4.8/trunk r190962 <mikpe@it.uu.se>]

gcc/cp/

2012-09-04  Jason Merrill  <jason@redhat.com>

	PR c++/54441
	* decl.c (reshape_init_class): Handle invalid initializer for
	0-length array member.

	* error.c (dump_type_suffix): Correct handling of 0-length arrays.

gcc/testsuite/

2012-09-04  Jason Merrill  <jason@redhat.com>

	PR c++/54441
	* g++.dg/ext/flexary3.C: New.

--- gcc-4.7.1/gcc/cp/decl.c.~1~	2012-05-10 23:06:42.000000000 +0200
+++ gcc-4.7.1/gcc/cp/decl.c	2012-09-08 20:58:59.000000000 +0200
@@ -5097,6 +5097,7 @@ reshape_init_class (tree type, reshape_i
   while (d->cur != d->end)
     {
       tree field_init;
+      constructor_elt *old_cur = d->cur;
 
       /* Handle designated initializers, as an extension.  */
       if (d->cur->index)
@@ -5129,6 +5130,15 @@ reshape_init_class (tree type, reshape_i
       if (field_init == error_mark_node)
 	return error_mark_node;
 
+      if (d->cur->index && d->cur == old_cur)
+	{
+	  /* This can happen with an invalid initializer for a flexible
+	     array member (c++/54441).  */
+	  if (complain & tf_error)
+	    error ("invalid initializer for %q#D", field);
+	  return error_mark_node;
+	}
+
       CONSTRUCTOR_APPEND_ELT (CONSTRUCTOR_ELTS (new_init), field, field_init);
 
       /* [dcl.init.aggr]
--- gcc-4.7.1/gcc/cp/error.c.~1~	2012-02-16 20:42:08.000000000 +0100
+++ gcc-4.7.1/gcc/cp/error.c	2012-09-08 20:58:59.000000000 +0200
@@ -846,7 +846,9 @@ dump_type_suffix (tree t, int flags)
 	{
 	  tree dtype = TYPE_DOMAIN (t);
 	  tree max = TYPE_MAX_VALUE (dtype);
-	  if (host_integerp (max, 0))
+	  if (integer_all_onesp (max))
+	    pp_character (cxx_pp, '0');
+	  else if (host_integerp (max, 0))
 	    pp_wide_integer (cxx_pp, tree_low_cst (max, 0) + 1);
 	  else if (TREE_CODE (max) == MINUS_EXPR)
 	    dump_expr (TREE_OPERAND (max, 0),
--- gcc-4.7.1/gcc/testsuite/g++.dg/ext/flexary3.C.~1~	1970-01-01 01:00:00.000000000 +0100
+++ gcc-4.7.1/gcc/testsuite/g++.dg/ext/flexary3.C	2012-09-08 20:58:59.000000000 +0200
@@ -0,0 +1,10 @@
+// PR c++/54441
+// { dg-options "" }
+
+struct s { char c[]; };
+
+int main()
+{
+    struct s s = { .c = 0 };	// { dg-error "initializer" }
+    return 0;
+}