removeAll and retainAll should receive semantic highlighting

That's because there exist retainAll and removeAll methods on Collection that are being chosen instead.

I did notice that content assist for list literals wasn't working for empty lists. Eg, []._ was not returning any useful proposals. There was a problem with our completion tokenizer. This is now fixed.

So, is the problem that you weren't seeing the content assist proposals, or that you want the editor to recognize the DGM method instead of the method on collection?

I guess I was expecting the editor to recognize the DGM method instead of the method on collection. But if that is a more specific case then perhaps that should be the expected behaviour.

The DGM methods exist so that the retain/removeAll methods can accept closures and arrays in addition to lists as their arguments.

Probably won't be able to do much with this right now, at least until we are able to determine inferencing results based on method call arguments.