See https://github.com/rust-lang/rust/issues/9795 and the linked PR that removed them.

> let tps = if_ok!(self.tps(as_.tps, bs.tps));

Ha, that's how the question mark operator (and the previous encarnation, the `try!` macro) was born then :)

Yup! https://github.com/rust-lang/rust/issues/12037