The code: ``` rust fn f<'a, T: Iterator<&'a int>>(arg_iter: &'a mut T) { arg_iter.next().unwrap().clone(); } ``` Produces an ICE when compiled (using rustc from master at time of writing): ``` yuriks@reinforce ~/rust-ice % rustc --lib main.rs main.rs:2:5: 2:30 error: internal compiler error: Cannot relate bound region: ReScope(23) <= ReLateBound(3, BrNamed(syntax::ast::DefId{crate: 0u32, node: 17u32}, a)) This message reflects a bug in the Rust compiler. We would appreciate a bug report: http://static.rust-lang.org/doc/master/complement-bugreport.html main.rs:2 arg_iter.next().unwrap().clone(); ^~~~~~~~~~~~~~~~~~~~~~~~~ 101 yuriks@reinforce ~/rust-ice % ```