BurntSushi/quickcheck — pull request #38 by japaric (2014-11-17 14:57:11+00:00)
Title: fix macro: `TyNil` has been removed, use zero-length `TyTup`

See rust-lang/rust#18752

AIUI, one should use a zero-length tuple instead of the removed unit type. Since there is no `ty_tup` constructor, I have constructed the zero length tuple type manually (using a dummy id/span as `ty_nil` did).