cpp::Reference ambiguous cast

[ibilon]

There's a problem when using unsafe cast on cpp::Reference:

extern class A { }
@:native("cpp::Reference<A>") extern clas ARef extends A { }

extern class B exends A { }
@:native("cpp::Reference<B>") extern clas BRef extends B {
@:native("new B") static public function create () : BRef;
}

If we get a BRef we can't directly assign it a variable of type ARef,
but unsafe casting doesn't work either:

var bref : BRef = Bref.create();
var aref : ARef = cast bref;

gives the following error with g++ both with the latest haxelib and github version:

error: call of overloaded ‘Reference(cpp::Reference<B>&)’ is ambiguous
this->aref = ((cpp::Reference<A>)(bref));

and four candidate constructors.

Changing the toolchain to clang gives the same error

error: ambiguous conversion for C-style cast from 'cpp::Reference<B>' to cpp::Reference<A>'
this->aref = ((cpp::Reference<A>)(bref));

This doesn't happen on windows.

A more "real" example can be found in https://github.com/ianharrigan/hxWidgets/blob/master/src/hx/widgets/Frame.hx#L15 (_ref is defined in parent's parent class https://github.com/ianharrigan/hxWidgets/blob/master/src/hx/widgets/EvtHandler.hx#L12)

[hughsando]

Here is an example that compiles:

extern class A { var a:Int; }
@:native("cpp::Reference<A>") extern class ARef extends A { }
extern class B extends ARef { var b:Int; }

@:native("cpp::Reference<B>") extern class BRef extends B
{
   @:native("new B") static public function create () : BRef;
}

@:cppFileCode("
  struct A { A() { a=1;} int a; };
  struct B : public A { B() { b=2;} int b; };
")
class Test
{
   public static function main()
   {
      var bref : BRef = BRef.create();
      trace(bref.b);
      var aref : ARef = bref;
      trace(aref.a);
   }
}