propagate failwith strings (also support for others) in the error

src/bin/expect_tests/contract_tests.ml

@@ -927,4 +927,8 @@ let%expect_test _ =
 
 let%expect_test _ =
   run_ligo_bad [ "compile-contract" ; contract "bad_type_operator.ligo" ; "main" ] ;
-  [%expect {| ligo: bad type operator (TO_Map (unit,unit)): |}] ;
+  [%expect {| ligo: bad type operator (TO_Map (unit,unit)): |}]
+
+let%expect_test _ =
+  run_ligo_bad [ "run-function" ; contract "failwith.ligo" ; "failer" ; "1" ] ;
+  [%expect {| ligo: Execution failed:  {"value":"some_string","type":"string"} |}]

src/main/run/of_michelson.ml

@@ -3,6 +3,21 @@ open Trace
 open Memory_proto_alpha.Protocol.Script_ir_translator
 open Memory_proto_alpha.X
 
+module Errors = struct
+  let unknown_failwith_type () =
+    let title () = "Execution failed with an unknown failwith type" in
+    let message () = "only bytes, string or int are printable" in
+    error title message
+
+  let failwith data_str type_str () =
+    let title () = "Execution failed" in
+    let message () = "" in
+    let data = [
+      ("value" , fun () -> Format.asprintf "%s" data_str);
+      ("type"  , fun () -> Format.asprintf "%s" type_str);
+    ] in
+    error ~data title message
+end
 type options = Memory_proto_alpha.options
 
 type run_res =
@@ -121,7 +136,12 @@ let run ?options (exp:Michelson.t) (exp_type:ex_ty) : ex_typed_value result =
   let%bind expr = run_expression ?options exp exp_type in
   match expr with
   | Success res -> ok res
-  | _  -> simple_fail "Execution terminated with failwith"
+  | Fail res -> ( match Tezos_micheline.Micheline.root @@ Memory_proto_alpha.strings_of_prims res with
+    | Int (_ , i)    -> fail @@ Errors.failwith (Z.to_string i) "int" ()
+    | String (_ , s) -> fail @@ Errors.failwith s "string" ()
+    | Bytes (_, s)   -> fail @@ Errors.failwith (Bytes.to_string s) "bytes" ()
+    | _              -> fail @@ Errors.unknown_failwith_type () )
+
 
 let run_failwith ?options (exp:Michelson.t) (exp_type:ex_ty) : run_failwith_res result =
   let%bind expr = run_expression ?options exp exp_type in
@@ -129,7 +149,7 @@ let run_failwith ?options (exp:Michelson.t) (exp_type:ex_ty) : run_failwith_res
   | Fail res -> ( match Tezos_micheline.Micheline.root @@ Memory_proto_alpha.strings_of_prims res with
     | Int (_ , i)    -> ok (Failwith_int (Z.to_int i))
     | String (_ , s) -> ok (Failwith_string s)
-    | Bytes (_,b)    -> ok (Failwith_bytes b)
+    | Bytes (_, b)    -> ok (Failwith_bytes b)
     | _              -> simple_fail "Unknown failwith type" )
   | _  -> simple_fail "An error of execution was expected"
 

src/test/contracts/failwith.ligo

@@ -31,3 +31,7 @@ function foobar (const i : int) : int is
   | Zero (n) -> i
   | Pos (n) -> (failwith ("waaaa") : int)
   end
+
+function failer(const p : int) : int is block {
+  if p = 1 then failwith("some_string") else skip ;
+} with p