C++: Default to one indirection in the case of self iterators.

Author: MathiasVP

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/SsaInternalsCommon.qll

@@ -117,6 +117,16 @@ private int countIndirections(Type t) {
   else (
     result = any(Indirection ind | ind.getType() = t).getNumberOfIndirections()
     or
+    // If there is an indirection for the type, but we cannot count the number of indirections
+    // it means we couldn't reach a non-indirection type by stripping off indirections. This
+    // can occur if an iterator specifies itself as the value type. In this case we default to
+    // 1 indirection fore the type.
+    exists(Indirection ind |
+      ind.getType() = t and
+      not exists(ind.getNumberOfIndirections()) and
+      result = 1
+    )
+    or
     not exists(Indirection ind | ind.getType() = t) and
     result = 0
   )