Avoids using expr.op0 when type is known

Author: klaas

src/util/expr_util.cpp

@@ -22,9 +22,9 @@ Author: Daniel Kroening, [email protected]
 bool is_lvalue(const exprt &expr)
 {
   if(expr.id()==ID_index)
-    return is_lvalue(to_index_expr(expr).op0());
+    return is_lvalue(to_index_expr(expr).array());
   else if(expr.id()==ID_member)
-    return is_lvalue(to_member_expr(expr).op0());
+    return is_lvalue(to_member_expr(expr).compound());
   else if(expr.id()==ID_dereference)
     return true;
   else if(expr.id()==ID_symbol)