The fact that list elements implements the 2 same ...

# compiler

[mbonnin]

The fact that list elements implements the 2 same interfaces seems to force List<Any> there. I guess because it could because List<Named> is as good of a solution than List<Node> ? But in the context of List<Node> , I feel like this could be disambiguated_?_

[Drew Hamilton]

Your analysis looks correct; if I remove Named as supertype of either Cat or Dog then the compiler stops complaining.

The ambiguity is in the return type of List’s + operator which is probably in some sense “before” it decides the return type of children? So it seems like the compiler would have to do like an extra pass to then disambiguate it later. But I’m just guessing at this point.