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  1. JDK
  2. JDK-8167336

Handling of static interface methods in JDI ObjectReference.invokeMethod is incorrect and incomplete



    • Bug
    • Resolution: Unresolved
    • P4
    • tbd
    • 8u40, 9
    • core-svc
    • b10


      Changes to JDI for static and default interface methods was added under JDK-8042123. But while investigating the changes needed for private interface methods in JDK-8165827 it became apparent that the specification with respect to static interface methods was incorrect. It states:

           * @throws java.lang.IllegalArgumentException if the method is not
           * a member of this object's class, if the size of the argument list
           * does not match the number of declared arguments for the method,
           * if the method is a constructor or static intializer, or
           * if {@link #INVOKE_NONVIRTUAL} is specified and the method is
           * either abstract or a non-default interface member.

      The last clause prohibits nonvirtual invocation of a static interface method, but it should be allowed according to the initial spec for the method:

           * Invokes the specified {@link Method} on this object in the
           * target VM. The
           * specified method can be defined in this object's class,
           * in a superclass of this object's class, or in an interface
           * implemented by this object. The method may be a static method
           * or an instance method, but not a static initializer or constructor.

      The implementation seems to support this as it delegates static method invocations to Interfacetype.invokeMethod or ClassType.invokeMethod as appropriate.

      That said it is unclear why only non-virtual invocations would be affected.

      On further reflection and examination of what is allowed at the Java language level I think the intent was that static interface methods can not be invoked via ObjectReference.invokeMethod, but the changes to the spec and the implementation were not consistent with that. I believe JDK-8042123 should have:

      a) Changed the initial part of the invokeMethod spec from:

      "The method may be a static method or an instance method, but not a static initializer or constructor."

      to read something like:

      "The method may be a static class method or an instance method, but not a static initializer, static interface method or constructor."


      b) Actually implemented the logic to throw IllegalArgumentException when called for a static interface method whether virtual or non-virtual

      Then the logic that dispatches to InterfaceType.invokeMethod is not needed and should be removed.

      And of course the @throws IllegalArgumentException should add "or is a static interface method" unconditionally.


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              Unassigned Unassigned
              dholmes David Holmes
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