You are right, it does not work. Actually this one is quite interesting, even the delomboked result fails in eclipse while it works in javac. I will check out how we can generate code that eclipse likes too.

Delomboked code:

public class WithInnerGeneric<Z> {
	class Inner {
		final String x;

		@java.lang.SuppressWarnings("all")
		public Inner(final String x) {
			this.x = x;
		}

		@java.lang.SuppressWarnings("all")
		public WithInnerGeneric<Z>.Inner withX(final String x) {
			return this.x == x ? this : new WithInnerGeneric<Z>.Inner(x);
		}
	}
}
}

It should be possible to always call the constructor using the nested class name instead of also adding the parent class. This seems to work in all cases I tried. I will change the behaviour and add test cases to cover all the different cases.

We can't generate just public Inner withX() {} - see issue #2268 for why that's problematic (and why this until recently did work; the fix for #2268 is recent and added the more partially qualified names to the output of @With and @Builder and such. We'll need to investigate if ecj is right or javac is right (usually ecj is right, but I do have my doubts here), and if there's anything we can generate that satisfies both ecj and javac and still addresses #2268. Tricky one.

Note that javac goes out of its way to allow you to have generics on each 'element' in a dotted type name, even though in common java you just never encounter generics anywhere except on the final element. This makes the code of javac considerably more convoluted, and ecj has this as well, which is a very light indication that in this particular instance, ecj's got it wrong, and this IS proper java syntax after all.

Not that the slam dunk case is then 'eh, whatever, ecj's problem, we shall ignore it' - but we're still just gathering info.

Uh, I totally missed that bug, sorry about that. I'm courious why all test cases still pass, I guess I have to understand #2268 completly but I'm to tired for that right now. One thing I noticed is that I only changed the constructor call to use the simple name and the returned type is still Outer.Inner.

@Rawi01 I don't think we ever created a test for #2268.

Yes, I added one and think that I found a solution, I need some more time to properly test all the different cases.