error: macros that expand to items must either be surrounded with braces or followed by a semicolon

[Boscop]

Why am I getting this error?

delegate_method! {
	impl PausablePlayer {
		player:
		pub fn jump_to(&mut self, dst_time: TickTime);
		pub fn rewind(&mut self);
	}
}

error: macros that expand to items must either be surrounded with braces or followed by a semicolon
error: this error originates in a macro outside of the current crate

[Boscop]

Hm, it works when I write:

delegate_method! {
	impl PausablePlayer {
		player as RunningPlayer:
		pub fn jump_to(&mut self, dst_time: TickTime);
		pub fn rewind(&mut self);
	}
}

But shouldn't as RunningPlayer be optional?