Fix crasher in rustc.

src/Makefile

@@ -465,6 +465,7 @@ TEST_XFAILS_LLVM := $(TASK_XFAILS) \
                       destructor-ordering.rs \
                       drop-bind-thunk-args.rs \
                       drop-on-empty-block-exit.rs \
+                      drop-parametric-closure-with-bound-box.rs \
                       export-non-interference.rs \
                       exterior.rs \
                       fn-lval.rs \

src/boot/be/abi.ml

@@ -62,10 +62,12 @@ let obj_body_elt_fields = 1;;
 let fn_field_code = binding_field_dispatch;;
 let fn_field_box = binding_field_bound_data;;
 
+(* NB: bound ty params come last to facilitate ignoring them on
+ * closure-dropping. *)
 let closure_body_elt_bound_args_tydesc = 0;;
 let closure_body_elt_target = 1;;
-let closure_body_elt_bound_ty_params = 2;;
-let closure_body_elt_bound_args = 3;;
+let closure_body_elt_bound_args = 2;;
+let closure_body_elt_bound_ty_params = 3;;
 
 let tag_elt_discriminant = 0;;
 let tag_elt_variant = 1;;

src/boot/me/semant.ml

@@ -2219,9 +2219,10 @@ let rec closure_box_rty
       r (Array.init n_ty_params (fun _ -> tydesc))
   in
   let bound_args = r (Array.map (slot_referent_type cx) bs) in
-    (* First tydesc is the one describing bound_args; second tydesc is the one
-     * to pass to targ when invoking it.  *)
-    r [| rc; r [| tydesc; targ; ty_param_rtys; bound_args |] |]
+    (* First tydesc is the one describing bound_args; second tydesc cluster
+     * are those to pass to targ when invoking it, along with the merged
+     * bound args. *)
+    r [| rc; r [| tydesc; targ; bound_args; ty_param_rtys |] |]
 
 and fn_rty (cx:ctxt) (opaque_box_body:bool) : Il.referent_ty =
   let s t = Il.ScalarTy t in

src/test/run-pass/drop-parametric-closure-with-bound-box.rs

@@ -0,0 +1,5 @@
+fn f[T](@int i, T t) {}
+
+fn main() {
+  auto x = bind f[char](@0xdeafbeef, _);
+}