[cleanup] make it possible to print FormalMap's

Reviewed By: ngorogiannis

Differential Revision: D6054161

fbshipit-source-id: a1f41d2

infer/src/absint/FormalMap.ml

@@ -40,3 +40,5 @@ let get_formal_base index t =
   |> Option.map ~f:fst
 
 let get_formals_indexes = AccessPath.BaseMap.bindings
+
+let pp = AccessPath.BaseMap.pp ~pp_value:Int.pp

infer/src/absint/FormalMap.mli

@@ -31,3 +31,6 @@ val get_formal_base : int -> t -> AccessPath.base option
     linear in the size of the formal map *)
 
 val get_formals_indexes : t -> (AccessPath.base * int) list
+(** Get a list of (base * index) pairs. Note: these are sorted by base, not index *)
+
+val pp : F.formatter -> t -> unit