[xmlvm-users] Multiple inner classes inheriting from each other lead to a gcc error.

[Brian S. <bri...@go...>]

Hi,

I'm completely new to XMLVM, but due to the external circumstances, I'm
forced to do something rather advanced with it, that is, a crosscompilation
of the Java 6.0 Collections Framework to Objective C. You might argue that
it might be better to use native Objective C collections and write bridges,
but as I need to get the same behaviour as on Java, I thought crosscompiling
would be nice. To make things easier for XMLVM I already used
Retrotranslator to crosscompile the Java 6.0 classes to Java 1.2, and
checked their validity on J2ME. As far as I can tell, my Java classes are
1.2 compilant and working, but crosscompilation to Objective C has its
quirks.

Let me first outline the class layout:

abstract class AbstractList extends AbstractCollection implements List
{
    class Itr implements Iterator
    {
        //...
    }

    class ListItr extends Itr implements ListIterator
    {
        //...
    }

    //..
}

AbstractList has two inner classes and one of those inherits from the other
one. The problem is, that both AbstractList$Itr and AbstractList$ListItr
have the following synthetic member in their bytecode:

final synthetic AbstractList this$0;

Crosscompilation to Objective C works fine and yields two files, each having
the line

@public packagename_AbstractList_* this$0;

but because one class extends the other, I get this error from gcc:

error: duplicate member 'this$0';

One option would be to change my Java code, but the Collections Framework
has at least 4 Classes with multiple (even more than two) inner classes
which inherit from each other. So I guess this case should somehow be
handled by the XMLVM crosscompiler, but I'm completely unsure how this would
be done. When emitting the interface in xmlvm2objc.xsl, we would need to
check if there is any superclass which is also an inner class, thus having a
this$0 field. I think this might be beyond the complexity of what should be
done here, isn't it?

Im happy about any advice.

With best regards,
Brian