<pre> import std::map; import std::map::hashmap; use std; type mut_elts = {mutable elts: [int]}; fn main() { let elts_hash = map::str_hash::<mut_elts>(); elts_hash.insert("foo", {mutable elts: []}); elts_hash.get("foo").elts += [1]; #error("%u", vec::len(elts_hash.get("foo").elts)); } </pre> I would expect to see 1 printed, but instead I see 0.