Data_encoding/Json: use strings for all int64

See Issue #190

scripts/protocol_parameters.json

@@ -7,10 +7,10 @@
   ],
   "dictator_pubkey":
     "edpkuSLWfVU1Vq7Jg9FucPyKmma6otcMHac9zG4oU1KMHSTBpJuGQ2",
-  "time_between_blocks" : [ 1, 0 ],
+  "time_between_blocks" : [ "1", "0" ],
   "blocks_per_roll_snapshot" : 4,
   "blocks_per_cycle" : 8,
   "preserved_cycles" : 2,
   "first_free_baking_slot" : 4,
-  "proof_of_work_threshold": -1
+  "proof_of_work_threshold": "-1"
 }

src/bin_client/test/protocol_parameters.json

@@ -20,10 +20,10 @@
   ],
   "dictator_pubkey":
     "edpkuSLWfVU1Vq7Jg9FucPyKmma6otcMHac9zG4oU1KMHSTBpJuGQ2",
-  "time_between_blocks" : [ 1, 0 ],
+  "time_between_blocks" : [ "1", "0" ],
   "blocks_per_cycle" : 128,
   "blocks_per_roll_snapshot" : 32,
   "preserved_cycles" : 1,
   "first_free_baking_slot" : 4,
-  "proof_of_work_threshold": -1
+  "proof_of_work_threshold": "-1"
 }

src/bin_client/tezos-init-sandboxed-client.sh

@@ -37,7 +37,7 @@ init_sandboxed_client() {
   ],
   "dictator_pubkey":
     "edpkuSLWfVU1Vq7Jg9FucPyKmma6otcMHac9zG4oU1KMHSTBpJuGQ2",
-  "time_between_blocks" : [ 1, 0 ],
+  "time_between_blocks" : [ "1", "0" ],
   "blocks_per_roll_snapshot" : 4,
   "blocks_per_cycle" : 8,
   "preserved_cycles" : 2,

src/lib_data_encoding/json.ml

@@ -31,18 +31,13 @@ let wrap_error f =
 
 let int64_encoding =
   let open Json_encoding in
-  union [
-    case
-      int32
-      (fun i ->
-         let j = Int64.to_int32 i in
-         if Int64.equal (Int64.of_int32 j) i then Some j else None)
-      Int64.of_int32 ;
-    case
-      string
-      (fun i -> Some (Int64.to_string i))
-      Int64.of_string
-  ]
+  def "int64"
+    ~title: "64 bit integers"
+    ~description: "Decimal representation of 64 bit integers" @@
+  conv
+    Int64.to_string
+    (wrap_error Int64.of_string)
+    string
 
 let n_encoding =
   let open Json_encoding in
@@ -51,8 +46,7 @@ let n_encoding =
     ~description: "Decimal representation of a positive big number" @@
   conv
     (fun z ->
-       if Z.sign z < 0 then
-         raise (Json_encoding.Cannot_destruct ([], Failure "negative natural")) ;
+       if Z.sign z < 0 then invalid_arg "negative natural" ;
        Z.to_string z)
     (fun s ->
        let n = Z.of_string s in

src/proto_alpha/lib_baking/test/proto_alpha_helpers.ml

@@ -76,12 +76,12 @@ let protocol_parameters =
     [ "btz1Q1N2ePwhVw5ED3aaRVek6EBzYs1GDkSVD", "3569618927693" ],
     [ "btz1VFFVsVMYHd5WfaDTAt92BeQYGK8Ri4eLy", "9034781424478" ]
   ],
-  "time_between_blocks" : [ 1, 0 ],
+  "time_between_blocks" : [ "1", "0" ],
   "blocks_per_cycle" : 4,
   "blocks_per_roll_snapshot" : 2,
   "preserved_cycles" : 1,
   "first_free_baking_slot" : 4,
-  "proof_of_work_threshold": -1
+  "proof_of_work_threshold": "-1"
 }
 |json} in
   match json_result with
@@ -99,13 +99,13 @@ let vote_protocol_parameters =
     [ "edpkuFrRoDSEbJYgxRtLx2ps82UdaYc1WwfS9sE11yhauZt5DgCHbU", "4000000000000" ],
     [ "edpkv8EUUH68jmo3f7Um5PezmfGrRF24gnfLpH3sVNwJnV5bVCxL2n", "4000000000000" ]
   ],
-  "time_between_blocks" : [ 1, 0 ],
+  "time_between_blocks" : [ "1", "0" ],
   "blocks_per_cycle" : 4,
   "blocks_per_roll_snapshot" : 2,
   "preserved_cycles" : 1,
   "first_free_baking_slot" : 4,
   "blocks_per_voting_period": 2,
-  "proof_of_work_threshold": -1
+  "proof_of_work_threshold": "-1"
 }
 |json} in
   match json_result with