HaxeFoundation.haxe/tests/misc/compiler_loops/projects/Issue6038/Main.hx

class Promise<T> {
	public function then<TOut>():Promise<TOut> { return null; }
}

typedef Thenable<T> = {
	function then():Thenable<T>;
}

class Main {
	static function main() {
		var p:Promise<Int> = null;
		var t:Thenable<Int> = p;
	}
}