C++: Replace the new rules in DataFlowUtil with a dataflow model for pointer wrapper classes.

cpp/ql/test/library-tests/dataflow/taint-tests/smart_pointer.cpp

@@ -9,7 +9,7 @@ template<typename T> void sink(std::unique_ptr<T>&);
 
 void test_make_shared() {
     std::shared_ptr<int> p = std::make_shared<int>(source());
-    sink(*p); // $ ast MISSING: ir
+    sink(*p); // $ ast,ir
     sink(p); // $ ast,ir
 }
 
@@ -21,7 +21,7 @@ void test_make_shared_array() {
 
 void test_make_unique() {
     std::unique_ptr<int> p = std::make_unique<int>(source());
-    sink(*p); // $ ast MISSING: ir
+    sink(*p); // $ ast,ir
     sink(p); // $ ast,ir
 }
 
@@ -83,3 +83,13 @@ void test_operator_arrow(std::unique_ptr<A> p, std::unique_ptr<B> q) {
   sink(q->a1.y);
   sink(q->a2.x);
 }
+
+void taint_x(A* pa) {
+    pa->x = source();
+}
+
+void reverse_taint_smart_pointer() {
+  std::unique_ptr<A> p = std::unique_ptr<A>(new A);
+  taint_x(p.get());
+  sink(p->x); // $ ast MISSING: ir
+}