re PR c/25682 (ICE when using old sytle offsetof (with non zero start) as array size)

	PR c/25682
	* c-typeck.c (build_unary_op): Fold offsetof-like expressions
	even when the pointer is not NULL.
cp/
	* decl.c (compute_array_index_type): After issuing not an integral
	constant-expression error, set size to 1 to avoid ICEs later on.
testsuite/
	* gcc.dg/pr25682.c: New test.
	* g++.dg/parse/array-size2.C: New test.

From-SVN: r109812

gcc/ChangeLog

+2006-01-17  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/25682
+	* c-typeck.c (build_unary_op): Fold offsetof-like expressions
+	even when the pointer is not NULL.
+
 2006-01-16  Ian Lance Taylor  <ian@airs.com>
 
 	* common.opt (ftoplevel-reorder): New option.

gcc/c-typeck.c

@@ -3003,8 +3003,13 @@ build_unary_op (enum tree_code code, tree xarg, int flag)
 	 when we have proper support for integer constant expressions.  */
       val = get_base_address (arg);
       if (val && TREE_CODE (val) == INDIRECT_REF
-	  && integer_zerop (TREE_OPERAND (val, 0)))
-	return fold_convert (argtype, fold_offsetof (arg));
+          && TREE_CONSTANT (TREE_OPERAND (val, 0)))
+	{
+	  tree op0 = fold_convert (argtype, fold_offsetof (arg)), op1;
+
+	  op1 = fold_convert (argtype, TREE_OPERAND (val, 0));
+	  return fold_build2 (PLUS_EXPR, argtype, op0, op1);
+	}
 
       val = build1 (ADDR_EXPR, argtype, arg);
 

gcc/cp/ChangeLog

+2006-01-17  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/25682
+	* decl.c (compute_array_index_type): After issuing not an integral
+	constant-expression error, set size to 1 to avoid ICEs later on.
+
 2006-01-16  Ian Lance Taylor  <ian@airs.com>
 
 	* parser.c: Include "cgraph.h".

gcc/cp/decl.c

@@ -6343,6 +6343,7 @@ compute_array_index_type (tree name, tree size)
 	       name);
       else
 	error ("size of array is not an integral constant-expression");
+      size = integer_one_node;
     }
   else if (pedantic)
     {

gcc/testsuite/ChangeLog

+2006-01-17  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/25682
+	* gcc.dg/pr25682.c: New test.
+	* g++.dg/parse/array-size2.C: New test.
+
 2006-01-16  Ian Lance Taylor  <ian@airs.com>
 
 	* consistency.vlad: Remove entire directory, 1652 files.

gcc/testsuite/g++.dg/parse/array-size2.C

+// PR c/25682
+// { dg-do compile }
+// Test whether we don't ICE on invalid array sizes.
+
+struct S
+{
+  char a[4];
+  int b;
+};
+
+extern void bar (char *, char *);
+
+void
+foo (void)
+{
+  char g[(char *) &((struct S *) 0)->b - (char *) 0];	// { dg-error "not an integral constant-expression" }
+  char h[(__SIZE_TYPE__) &((struct S *) 8)->b];		// { dg-error "not an integral constant-expression" }
+  bar (g, h);
+}

gcc/testsuite/gcc.dg/pr25682.c

+/* PR c/25682 */
+/* { dg-do compile } */
+/* Test whether we don't ICE on questionable constructs where offsetof
+   should have been used instead.  */
+
+struct S
+{
+  char a[4];
+  int b;
+};
+
+char c[(char *) &((struct S *) 0)->b - (char *) 0];
+char d[(__SIZE_TYPE__) &((struct S *) 8)->b];
+char e[sizeof (c) == __builtin_offsetof (struct S, b) ? 1 : -1];
+char f[sizeof (d) == __builtin_offsetof (struct S, b) + 8 ? 1 : -1];
+
+extern void bar (char *, char *);
+
+void
+foo (void)
+{
+  char g[(char *) &((struct S *) 0)->b - (char *) 0];
+  char h[(__SIZE_TYPE__) &((struct S *) 8)->b];
+  char i[sizeof (g) == __builtin_offsetof (struct S, b) ? 1 : -1];
+  char j[sizeof (h) == __builtin_offsetof (struct S, b) + 8 ? 1 : -1];
+  bar (g, h);
+}