rust-lang/rust — pull request #19703 by nikomatsakis (2014-12-10 17:08:30+00:00)
Title: Implement `unsafe trait` and `unsafe impl` from the OIBIT RFC

This PR allows declaring traits and impls as `unsafe`. An `unsafe` trait requires an `unsafe` impl. An `unsafe` impl does not permit unsafe code within its interior (unless that code is contained within an unsafe block or unsafe fn, as normal). The commits are standalone.

r? @alexcrichton
cc #13231