Re: Eclipse 3.0

[Robert Lougher]

Amazing.  I've only just got this.

Thanks for the clarification, but as Jeroen said, irrelevant to us as
VM implementors.  To be robust, we have to handle invokeinterface on a
method that only exists in Object.

Rob.

On Tue, 06 Jul 2004 06:27:52 -0600, Eric Blake <address@hidden> wrote:
> Robert Lougher wrote:
> > OK, I'm yelling :)  Please don't use Mark's patch!
> >
> > It "fixes" it by stopping resolution finding the method on Object.
> > However, it is legal to have an invokeinterface on an Object method
> > (as all interfaces subclass Object).
> >
> > Instead, please use the attached patch to the interpreter.  This
> > converts an invokeinterface on an Object method into an invokevirtual
> > (which is what 1.4 javac does anyway, but not jikes or 1.3 javac).
> 
> The JVMS is clear that invokeinterface is only to be used on interface 
> methods.  JLS 13.1 also states that a method call of something that (also)
> exists in Object is converted into a method call directly on Object if and
> only if the method was not redeclared along the type hierarchy of the type of
> the method call's qualifying expression.  All versions of javac to date are
> buggy in some regard on this matter, but the latest jikes is emitting correct
> code.  So, a correct compiler produces:
> 
> class A {
>   public String toString() { return ""; }
> }
> interface B {
>   int hashCode();
> }
> class C extends A implements B {
>   public boolean equals(Object o) { return false; }
>   {
>     toString(); // invokevirtual C.toString; javac 1.3 is wrong
>     ((A) this).toString(); // invokevirtual A.toString
>     ((B) this).toString(); // invokevirtual Object.toString
>     hashCode(); // invokevirtual Object.hashCode
>     ((A) this).hashCode(); // invokevirtual Object.hashCode
>     ((B) this).hashCode(); // invokeinterface B.hashCode; javac 1.4 is wrong
>     equals(null); // invokevirtual C.equals
>     ((A) this).equals(null); // invokevirtual Object.equals
>     ((B) this).equals(null); // invokevirtual Object.equals
> 
> 
>   }
> }
> 
> --
> Someday, I might put a cute statement here.
> 
> Eric Blake             address@hidden
>