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isSubsignature() of method bindings returns false for calls of methods with type parameter [message #1715145]

Thu, 19 November 2015 15:25

Johannes Dorn

Messages: 61
Registered: June 2013

Member

Scenario

interface IMyInterface {
   <T> T m(T arg);
}

class Example {

   void m(IMyInterface arg0, Example arg1) { 
      arg0.m(arg1);
   }

}

I have the method binding for the invocation of m:
public abstract Example m(Example)

and the method binding for the declaration in IMyInterface:
public abstract T m(T)

I believe the former should be a subsignature of the latter. However, isSubSignature() returns false.

If i rewrite the scenario slightly by moving the type parameter to the class level, isSubsignature() returns true:

interface IMyInterface<T> {
   T m(T arg);
}

class Example {

   void m(IMyInterface arg0, Example arg1) { 
      arg0.m(arg1);
   }

}

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Re: isSubsignature() of method bindings returns false for calls of methods with type parameter [message #1715149 is a reply to message #1715145]

Thu, 19 November 2015 15:47

Stephan Herrmann

Messages: 1853
Registered: July 2009

Senior Member

Please try org.eclipse.jdt.core.dom.IMethodBinding.getMethodDeclaration() on the binding obtained from the invocation. That should give you the exact same binding as you get from the interface (and obviously, isSubsignature() should answer true when comparing).

A binding from the invocation of a generic method is expected to be more specific than the generic method itself.
Makes sense?
Stephan

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Re: isSubsignature() of method bindings returns false for calls of methods with type parameter [message #1715153 is a reply to message #1715149]

Thu, 19 November 2015 16:22

Johannes Dorn

Messages: 61
Registered: June 2013

Member

Thank you very much! That seems to solve my problem.

One further question, though: can getMethodDeclaration() return null or is a non-null binding guaranteed?

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