Differences in desugared output from GHC 7.2.1 -O0, note: Any?? -> Any

Fun.dump-ds

destroyer:inc2 nhowell$ diff one/Fun.dump-ds two/Fun.dump-ds 
1c1
< Result size = 78
---
> Result size = 84
69c69
<     @ (GHC.Prim.Any?? -> GHC.Prim.Any?? -> GHC.Types.Int)
---
>     @ (GHC.Prim.Any -> GHC.Prim.Any?? -> GHC.Types.Int)
72,75c72,78
<        @ (GHC.Prim.Any?? -> GHC.Prim.Any?? -> GHC.Types.Int)
<        (Inc.$fArityx
<           @ (GHC.Prim.Any?? -> GHC.Prim.Any?? -> GHC.Types.Int)))
<     (\ _ _ -> GHC.Types.I# 3)
---
>        @ (GHC.Prim.Any -> GHC.Prim.Any?? -> GHC.Types.Int)
>        (Inc.$fArity(->)
>           @ (GHC.Prim.Any?? -> GHC.Types.Int)
>           @ GHC.Prim.Any
>           (Inc.$fArityx @ (GHC.Prim.Any?? -> GHC.Types.Int))))
>     (\ (x_arc :: GHC.Prim.Any) _ ->
>        case x_arc of _ { __DEFAULT -> GHC.Types.I# 3 })

Fun.dump-simpl

destroyer:inc2 nhowell$ diff one/Fun.dump-simpl two/Fun.dump-simpl
1c1
< Result size = 74
---
> Result size = 80
3c3
< $dArity_rrt :: Inc.Arity (GHC.Types.Int -> GHC.Types.Int)
---
> $dArity_rru :: Inc.Arity (GHC.Types.Int -> GHC.Types.Int)
5c5
< $dArity_rrt =
---
> $dArity_rru =
9c9
< $dArity1_rru
---
> $dArity1_rrv
12c12
< $dArity1_rru =
---
> $dArity1_rrv =
14c14
<     @ (GHC.Types.Int -> GHC.Types.Int) @ GHC.Types.Int $dArity_rrt
---
>     @ (GHC.Types.Int -> GHC.Types.Int) @ GHC.Types.Int $dArity_rru
26c26
<         $dArity1_rru)
---
>         $dArity1_rrv)
68c68
<     ($dArity1_rru
---
>     ($dArity1_rrv
82c82
<     @ (GHC.Prim.Any?? -> GHC.Prim.Any?? -> GHC.Types.Int)
---
>     @ (GHC.Prim.Any -> GHC.Prim.Any?? -> GHC.Types.Int)
84,85c84,87
<     ((Inc.$fArityx             <--------- here is the base case, where '0' is returned instead of '2'
<         @ (GHC.Prim.Any?? -> GHC.Prim.Any?? -> GHC.Types.Int))
---
>     ((Inc.$fArity(->)           <--------- GHC selects a different overload once it knows the variable(s) are live
>         @ (GHC.Prim.Any?? -> GHC.Types.Int)
>         @ GHC.Prim.Any
>         (Inc.$fArityx @ (GHC.Prim.Any?? -> GHC.Types.Int)))
87,88c89,90
<                <GHC.Prim.Any?? -> GHC.Prim.Any?? -> GHC.Types.Int>
<              :: Inc.T:Arity (GHC.Prim.Any?? -> GHC.Prim.Any?? -> GHC.Types.Int)
---
>                <GHC.Prim.Any -> GHC.Prim.Any?? -> GHC.Types.Int>
>              :: Inc.T:Arity (GHC.Prim.Any -> GHC.Prim.Any?? -> GHC.Types.Int)
90c92
<                 ((GHC.Prim.Any?? -> GHC.Prim.Any?? -> GHC.Types.Int)
---
>                 ((GHC.Prim.Any -> GHC.Prim.Any?? -> GHC.Types.Int)
92c94,95
<     (\ _ _ -> GHC.Types.I# 3)
---
>     (\ (x_arc :: GHC.Prim.Any) _ ->
>        case x_arc of _ { __DEFAULT -> GHC.Types.I# 3 })

Fun.hs

destroyer:inc2 nhowell$ diff one/Fun.hs two/Fun.hs 
22c22
< zero = arity $ \x y -> (3 :: Int)
---
> zero = arity $ \x y -> x `seq` (3 :: Int)