When copying function values, null out the destination's binding iff the source's binding is null.

src/boot/me/trans.ml

@@ -2933,12 +2933,18 @@ let trans_visitor
       : unit =
     drop_ty (get_ty_params_of_current_frame()) cell ty None
 
+  (* Returns a mark for a jmp that must be patched to the continuation of
+   * the null case (i.e. fall-through means not null).
+   *)
   and null_check (cell:Il.cell) : quad_idx =
     emit (Il.cmp (Il.Cell cell) zero);
     let j = mark() in
       emit (Il.jmp Il.JE Il.CodeNone);
       j
 
+  (* Returns a mark for a jmp that must be patched to the continuation of
+   * the non-zero refcount case (i.e. fall-through means zero refcount).
+   *)
   and drop_refcount_and_cmp (boxed:Il.cell) : quad_idx =
     iflog (fun _ -> annotate "drop refcount and maybe free");
     let rc = box_rc_cell boxed in
@@ -3268,7 +3274,14 @@ let trans_visitor
                       dst_binding (Ast.TY_box Ast.TY_int)
                       src_binding (Ast.TY_box Ast.TY_int)
                       curr_iso;
-                    patch null_jmp
+                    let end_jmp = mark() in
+                      emit (Il.jmp Il.JMP Il.CodeNone);
+                      patch null_jmp;
+                      (* The src had a null binding, so make sure the dst
+                       * does now too.
+                       *)
+                      mov dst_binding zero;
+                      patch end_jmp
               end
 
           | _ ->

src/test/run-pass/lib-map.rs

@@ -13,11 +13,8 @@ fn test_simple() {
     ret u;
   }
 
-  // FIXME we don't really want to bind here but if we don't then the
-  // hashmap's drop glue UMRs when trying to drop these functions, which
-  // it stores internally.
-  let map.hashfn[uint] hasher = bind hash(_);
-  let map.eqfn[uint] eqer = bind eq(_, _);
+  let map.hashfn[uint] hasher = hash;
+  let map.eqfn[uint] eqer = eq;
   let map.hashmap[uint, uint] hm = map.mk_hashmap[uint, uint](hasher, eqer);
 
   hm.insert(10u, 12u);
@@ -43,7 +40,7 @@ fn test_simple() {
 fn test_growth() {
   log "*** starting test_growth";
 
-  let uint map_capacity = 64u;  // Keep in sync with map.mk_hashmap
+  let uint num_to_insert = 64u;
 
   fn eq(&uint x, &uint y) -> bool { ret x == y; }
   fn hash(&uint u) -> uint {
@@ -52,13 +49,12 @@ fn test_growth() {
     ret u;
   }
 
-  // FIXME: as in test_simple(), don't really want to bind.
-  let map.hashfn[uint] hasher = bind hash(_);
-  let map.eqfn[uint] eqer = bind eq(_, _);
+  let map.hashfn[uint] hasher = hash;
+  let map.eqfn[uint] eqer = eq;
   let map.hashmap[uint, uint] hm = map.mk_hashmap[uint, uint](hasher, eqer);
 
   let uint i = 0u;
-  while (i < map_capacity) {
+  while (i < num_to_insert) {
     hm.insert(i, i * i);
     log "inserting " + std._uint.to_str(i, 10u)
       + " -> " + std._uint.to_str(i * i, 10u);
@@ -68,22 +64,22 @@ fn test_growth() {
   log "-----";
 
   i = 0u;
-  while (i < map_capacity) {
+  while (i < num_to_insert) {
     log "get(" + std._uint.to_str(i, 10u) + ") = "
       + std._uint.to_str(hm.get(i), 10u);
     check (hm.get(i) == i * i);
     i += 1u;
   }
 
-  hm.insert(map_capacity, 17u);
-  check (hm.get(map_capacity) == 17u);
+  hm.insert(num_to_insert, 17u);
+  check (hm.get(num_to_insert) == 17u);
 
   log "-----";
 
   hm.rehash();
 
   i = 0u;
-  while (i < map_capacity) {
+  while (i < num_to_insert) {
     log "get(" + std._uint.to_str(i, 10u) + ") = "
       + std._uint.to_str(hm.get(i), 10u);
     check (hm.get(i) == i * i);