Decouple Transaction_snark_work types

Remove `Stable.Latest.t = t` from interfaces. This is a preparation step
for removing the equality in the implementation as well.

src/lib/mina_lib/mina_lib.ml

@@ -1579,7 +1579,9 @@ let fetch_completed_snarks (module Context : CONTEXT) snark_pool network
       let%bind () =
         Deferred.List.iter completed_works ~f:(fun work ->
             (* proofs should be verified in apply and broadcast *)
-            let statement = Transaction_snark_work.statement work in
+            let statement =
+              Transaction_snark_work.Stable.Latest.statement work
+            in
             let snark =
               Network_pool.Priced_proof.
                 { proof = work.proofs

src/lib/mina_networking/mina_networking.mli

@@ -112,7 +112,7 @@ module Rpcs : sig
   module Get_completed_snarks : sig
     type query = unit
 
-    type response = Transaction_snark_work.unchecked list option
+    type response = Transaction_snark_work.Stable.Latest.t list option
   end
 
   type ('query, 'response) rpc = ('query, 'response) Rpcs.rpc =

src/lib/mina_networking/rpcs.ml

@@ -880,7 +880,7 @@ module Get_completed_snarks = struct
     | Some snark_pool, Some snark_state ->
         Work_selector.completed_work_statements ~snark_pool snark_state
         |> Fn.flip List.take limit
-        |> List.map ~f:Transaction_snark_work.forget
+        |> List.map ~f:Transaction_snark_work.(Fn.compose unwrap forget)
         |> Option.some |> return
     | _, _ ->
         return None

src/lib/staged_ledger_diff/diff.ml

@@ -178,9 +178,11 @@ module Make_str (A : Wire_types.Concrete) = struct
     type t =
       (Transaction_snark_work.t, User_command.t With_status.t) Pre_diff_two.t
 
-    let generate : Stable.Latest.t -> t = Fn.id
+    let generate : Stable.Latest.t -> t =
+      Pre_diff_two.map ~f1:Transaction_snark_work.generate ~f2:Fn.id
 
-    let unwrap : t -> Stable.Latest.t = Fn.id
+    let unwrap : t -> Stable.Latest.t =
+      Pre_diff_two.map ~f1:Transaction_snark_work.unwrap ~f2:Fn.id
   end
 
   module Pre_diff_with_at_most_one_coinbase = struct
@@ -202,9 +204,11 @@ module Make_str (A : Wire_types.Concrete) = struct
     type t =
       (Transaction_snark_work.t, User_command.t With_status.t) Pre_diff_one.t
 
-    let generate : Stable.Latest.t -> t = Fn.id
+    let generate : Stable.Latest.t -> t =
+      Pre_diff_one.map ~f1:Transaction_snark_work.generate ~f2:Fn.id
 
-    let unwrap : t -> Stable.Latest.t = Fn.id
+    let unwrap : t -> Stable.Latest.t =
+      Pre_diff_one.map ~f1:Transaction_snark_work.unwrap ~f2:Fn.id
   end
 
   module Diff = struct

src/lib/transaction_snark_work/transaction_snark_work.ml

@@ -97,6 +97,8 @@ module T = struct
         }
       [@@deriving yojson]
 
+      let statement t = One_or_two.map t.proofs ~f:Ledger_proof.statement
+
       let to_latest = Fn.id
     end
   end]
@@ -117,6 +119,10 @@ module T = struct
     ; fee = t.fee
     ; prover = t.prover
     }
+
+  let generate = Fn.id
+
+  let unwrap = Fn.id
 end
 
 include T

src/lib/transaction_snark_work/transaction_snark_work.mli

@@ -61,7 +61,7 @@ module type S = sig
   val proofs : t -> Ledger_proof.t One_or_two.t
 end
 
-type t = Mina_wire_types.Transaction_snark_work.V2.t =
+type t =
   { fee : Currency.Fee.t
   ; proofs : Ledger_proof.t One_or_two.t
   ; prover : Public_key.Compressed.t
@@ -76,9 +76,15 @@ val statement : t -> Statement.t
 module Stable : sig
   module V2 : sig
     type t [@@deriving bin_io, version, yojson]
+
+    val statement : t -> Statement.Stable.V2.t
+
+    val to_latest : t -> t
   end
+
+  module Latest = V2
 end
-with type V2.t = t
+with type V2.t = Mina_wire_types.Transaction_snark_work.V2.t
 
 type unchecked = t
 
@@ -93,3 +99,7 @@ module Checked : sig
 end
 
 val forget : Checked.t -> t
+
+val generate : Stable.Latest.t -> t
+
+val unwrap : t -> Stable.Latest.t