java - A functional interface that extends other can't - can't assign constructor reference to it - Is it compiler bug? -

in simple code below can see 'factory' interfaces, different between them factory0bad extends supplier:

@functionalinterface public static interface factory0bad<t> extends supplier<t> {     t get(); }  @functionalinterface public static interface factory0good<t>  {     t get(); }  public static class handler {} public static class handlera extends handler {}  public static void main(string[] args) {     // line compiles     factory0good<? extends handler> = handlera::new;      // not!     factory0bad<? extends handler> bad = handlera::new; } 

so line

factory0good<? extends handler> = handlera::new; 

is accepted compiler (1.8.0u05), line

factory0bad<? extends handler> bad = handlera::new; 

is not.

why this? missing here? bug in javac?

 // not!         // 1.8.0_05 - fails         // 1.8.0_40 - succeeds         // 1.8.0_45 - succeeds         factory0bad<? extends handler> bad = handlera::new;