Polymorphic call graph

Before implementing

Include polymorphic calls into the call graph. The three kinds of calls are MethodCallExpr (depends on the scope for its target), ObjectCreationExpr (target is always clear) and ExplicitConstructorInvocation (target is always clear).

The only case we're interested in is MethodCallExpr where the target is not static. In that case, we need to find the possible dynamic types of the scope. If there is no scope, this is used (static calls have been discarded). The scope can be any expression, such as:

• this: the current object can be its static type and any derivative.
• Variable or field: we're able to obtain the intra-procedural dynamic type with the resolver.
• Method call: The possible output types, which can be precomputed by examining the -output- variable. This requires an improvement to the DynamicTypeResolver to be able to determine transitive types (Object a = new String(); return a;, thus the return value must be a String).

After implementing

I haven't used the DynamicTypeResolver, but its inclusion is relatively easy. For now, the computed types and all their subtypes are used to generate polymorphic calls. A couple of examples have already been improved by doing so.

Caveats

default methods in interfaces are not supported, there is a TODO item left in the code.