Fix a crashing bug with type comparison.

Author: martin

regression/goto-analyzer/variable-sensitivity-bug-01/main.c

@@ -0,0 +1,14 @@
+struct st {
+              int a;
+              int b;
+};
+
+struct st sts_inf;
+
+void func( struct st* inf);      // no body
+
+void main(void)
+{
+    func(&sts_inf);     // assertion failed here
+}
+

regression/goto-analyzer/variable-sensitivity-bug-01/test.desc

@@ -0,0 +1,6 @@
+CORE
+main.c
+--variable-sensitivity --structs --arrays --pointers --show
+^EXIT=0$
+^SIGNAL=0$
+--

src/analyses/variable-sensitivity/constant_pointer_abstract_object.cpp

@@ -328,7 +328,7 @@ sharing_ptrt<pointer_abstract_objectt>
     if(stack.empty())
     {
       // We should not be changing the type of an abstract object
-      PRECONDITION(new_value->type()==type().subtype());
+      PRECONDITION(new_value->type()==ns.follow(type().subtype()));
 
       // Get an expression that we can assign to
       exprt value=value_stack.to_expression().op0();