[infer] Remove ppx_compare workaround for nonrec types

Summary:
The past issue with ppx_compare on nonrec types has (at some point)
been fixed. Cf. https://github.com/janestreet/ppx_compare/issues/2

Reviewed By: ngorogiannis

Differential Revision: D21961645

fbshipit-source-id: de03a60a4

infer/src/IR/Annot.ml

@@ -85,13 +85,8 @@ and pp fmt annotation =
 
 
 module Item = struct
-  (* Don't use nonrec due to https://github.com/janestreet/ppx_compare/issues/2 *)
-  (* type nonrec t = list (t, bool) [@@deriving compare]; *)
-
   (** Annotation for one item: a list of annotations with visibility. *)
-  type t_ = (t * bool) list [@@deriving compare]
-
-  type t = t_ [@@deriving compare]
+  type nonrec t = (t * bool) list [@@deriving compare]
 
   (** Pretty print an item annotation. *)
   let pp fmt ann =

infer/src/checkers/SiofTrace.ml

@@ -42,11 +42,7 @@ module TraceElem = struct
 
 
   module Set = PrettyPrintable.MakePPSet (struct
-    (* Don't use nonrec due to https://github.com/janestreet/ppx_compare/issues/2 *)
-    (* type nonrec t = t [@@deriving compare]; *)
-    type nonrec t = t
-
-    let compare = compare
+    type nonrec t = t [@@deriving compare]
 
     let pp = pp
   end)