The fourth single , `` Cross You Out '' featuring Sky Ferreira , was released on 16 August , followed by the singles , `` Warm '' , featuring American pop rock band HAIM , on 30 August ; “ February 2017 ” , featuring Clairo and Yaeji , on 6 September ; and `` 2099 '' , featuring Troye Sivan , on 10 September.
Charli XCX fifth single is `` Warm '' , her sixth single is “ February 2017 ” .