type ctxt = { v: uint }; trait get_ctxt { // Here the `&` is bound in the method definition: fn get_ctxt() -> &ctxt; } type has_ctxt = { c: &ctxt }; impl of get_ctxt for has_ctxt { // Here an error occurs because we used `&self` but // the definition used `&`: fn get_ctxt() -> &self/ctxt { //~ ERROR method `get_ctxt` has an incompatible type self.c } } fn get_v(gc: get_ctxt) -> uint { gc.get_ctxt().v } fn main() { let ctxt = { v: 22u }; let hc = { c: &ctxt }; assert get_v(hc as get_ctxt) == 22u; }