[cs] StackOverflowException when using abstract builder with fluent API

[sebthom]

The following code results in a StackOverflowException when targeting CSharp, but works for all other targets:

abstract class AbstractFluentObject<This:AbstractFluentObject<This>> {
   public function new() {}
   public function setName(name:String):This {
      return cast this;
   }
}

class ConcreteFluentObject extends AbstractFluentObject<ConcreteFluentObject> {
   public function new() {
      super();
   }
}

class Test {
  static function main() {
    trace(new ConcreteFluentObject().setName("test"));
  }
}

If I remove the abstract keyword, then the StackOverflowException goes way.

If the abstract keyword is present the following code is generated which results in the StackOverflow:

public virtual object AbstractFluentObject_cast<This_c>() {
   return this.AbstractFluentObject_cast<This>();
}

If I remove the abstract keyword, this code is generated:

public virtual object AbstractFluentObject_cast<This_c>() {
	if (global::haxe.lang.Runtime.eq(typeof(This), typeof(This_c))) {
		return this;
	}
			
	global::AbstractFluentObject<This_c> new_me = new global::AbstractFluentObject<This_c>(global::haxe.lang.EmptyObject.EMPTY);
	global::Array<string> fields = global::Reflect.fields(this);
	int i = 0;
	while (( i < fields.length )) {
		string field = fields[i++];
		global::Reflect.setField(new_me, field, global::Reflect.field(this, field));
	}
	
	return new_me;
}