Description Stephan Herrmann 2016-07-02 14:11:47 EDT

See https://bugs.openjdk.java.net/browse/JDK-8148464 for a situation that ecj accepts, while according to Dan ambiguity should be reported.

Here's the example:
//---
public interface GenericInterface<V> {
  void setValue(V value);
}
public interface TypedInterface {
  void setValue(Boolean value);
}
public interface CombinedInterface extends GenericInterface<Boolean>, TypedInterface {
  default void set(boolean value) {
    setValue(Boolean.valueOf(value));
  }
} 
//---

both methods *would* collapse to being the same method, if generic instantiations should be used. However, 15.12.2.5 requires comparison of erasures instead.
- more than one maximally specific method (both are setValue(Boolean)),
- different erasures (setValue(Boolean) vs. setValue(Object))
=> ambiguity

I don't have an intuitive explanation why this code is not kosher, but we should comply with JLS.