re PR c++/38699 (ICE using offsetof with pointer and array accesses)

Fix PR c++/38699

gcc/ChangeLog:

	PR c++/38699
	* c-common.c (fold_offsetof_1): Issue errors when the
	member designator of the offsetoff expression is not legitimate.

gcc/testsuite/ChangeLog:

	* c-c++-common/dfp/builtin-offsetof.c: New test.
	* g++.dg/other/offsetof6.C: Likewise.

From-SVN: r153843

gcc/ChangeLog

+2009-11-03  Dodji Seketeli  <dodji@redhat.com>
+
+	PR c++/38699
+	* c-common.c (fold_offsetof_1): Issue errors when the member designator
+	of the offsetoff expression is not legitimate.
+
 2009-11-03  Uros Bizjak  <ubizjak@gmail.com>
 
 	* config/i386/i386.md (*call_value_1_rex64_ms_sysv): Use register

gcc/c-common.c

@@ -8356,15 +8356,14 @@ fold_offsetof_1 (tree expr, tree stop_ref)
       error ("cannot apply %<offsetof%> when %<operator[]%> is overloaded");
       return error_mark_node;
 
-    case INTEGER_CST:
-      gcc_assert (integer_zerop (expr));
-      return size_zero_node;
-
     case NOP_EXPR:
     case INDIRECT_REF:
-      base = fold_offsetof_1 (TREE_OPERAND (expr, 0), stop_ref);
-      gcc_assert (base == error_mark_node || base == size_zero_node);
-      return base;
+      if (!integer_zerop (TREE_OPERAND (expr, 0)))
+	{
+	  error ("cannot apply %<offsetof%> to a non constant address");
+	  return error_mark_node;
+	}
+      return size_zero_node;
 
     case COMPONENT_REF:
       base = fold_offsetof_1 (TREE_OPERAND (expr, 0), stop_ref);
@@ -8397,6 +8396,16 @@ fold_offsetof_1 (tree expr, tree stop_ref)
 	}
       t = convert (sizetype, t);
       off = size_binop (MULT_EXPR, TYPE_SIZE_UNIT (TREE_TYPE (expr)), t);
+
+      /* Check if the offset goes beyond the upper bound of the array.  */
+      {
+	tree nelts = array_type_nelts (TREE_TYPE (TREE_OPERAND (expr, 0)));
+        HOST_WIDE_INT index = int_cst_value (t);
+	if (index > int_cst_value (nelts))
+	  warning (OPT_Warray_bounds,
+		   "index %ld denotes an offset greater than size of %qT",
+		   index, TREE_TYPE (TREE_OPERAND (expr, 0)));
+      }
       break;
 
     case COMPOUND_EXPR:

gcc/testsuite/ChangeLog

+2009-11-03  Dodji Seketeli  <dodji@redhat.com>
+
+	PR c++/38699
+	* c-c++-common/dfp/builtin-offsetof.c: New test.
+	* g++.dg/other/offsetof6.C: Likewise.
+
 2009-11-03  Uros Bizjak  <ubizjak@gmail.com>
 
 	PR target/41900

gcc/testsuite/c-c++-common/dfp/builtin-offsetof.c

+// Contributed by Dodji Seketeli <dodji@redhat.com>
+// Origin PR c++/38699
+// { dg-options "-Warray-bounds" }
+// { dg-do compile }
+
+struct A
+{
+  const char *p;
+};
+
+struct B
+{
+    char p[10];
+    struct A a;
+};
+
+void
+f0 ()
+{
+  __builtin_offsetof(struct A, p); // OK
+  __builtin_offsetof(struct A, p[0]); // { dg-error "non constant address" }
+  __builtin_offsetof(struct B, p[0]); // OK
+  __builtin_offsetof(struct B, p[9]); // OK
+  __builtin_offsetof(struct B, p[10]); // { dg-warning "greater than size" }
+  __builtin_offsetof(struct B, a.p); // OK
+  __builtin_offsetof(struct B, p[0]); // OK
+  __builtin_offsetof(struct B, a.p[0]); // { dg-error "non constant address" }
+}
+

gcc/testsuite/g++.dg/other/offsetof6.C

+// Contributed by Dodji Seketeli <dodji@redhat.com>
+// Origin PR c++/38699
+// { dg-do compile }
+
+template<class T>
+struct A
+{
+  const T *p;
+};
+
+struct B
+{
+  A<int> a;
+};
+
+template class A<char>;
+
+void
+f0 ()
+{
+  __builtin_offsetof(A<char>, p); // OK
+  __builtin_offsetof(A<char>, p[1]); // { dg-error "non constant address" }
+  __builtin_offsetof(B, a.p); // OK
+  __builtin_offsetof(B, a.p[1]); // { dg-error "non constant address" }
+}
+