fix(builtins): bystr20_to_bech32's None type parameter (#1166)

See also Zilliqa/scilla-docs#166

src/eval/EvalBuiltins.ml

@@ -675,15 +675,14 @@ module ScillaEvalBuiltIns (SR : Rep) (ER : Rep) = struct
     let bystr20_to_bech32 _ ls _ =
       match ls with
       | [ StringLit prfx; ByStrX addr ] -> (
-          if Core.String.(prfx <> "zil") then
-            pure @@ build_none_lit (bystrx_typ Type.address_length)
+          if Core.String.(prfx <> "zil") then pure @@ build_none_lit string_typ
           else
             match
               Bech32.encode_bech32_addr ~prfx ~addr:(Bystrx.to_raw_bytes addr)
             with
             | Some bech32 ->
                 pure @@ build_some_lit (StringLit bech32) string_typ
-            | None -> pure @@ build_none_lit (bystrx_typ Type.address_length))
+            | None -> pure @@ build_none_lit string_typ)
       | _ -> builtin_fail "Crypto.bystr20_to_bech32" ls
 
     let concat _ ls _ =

tests/eval/good/Good.ml

@@ -49,6 +49,7 @@ let explist =
     "builtin-bech32-3.scilexp";
     "builtin-bech32-4.scilexp";
     "builtin-bech32-5.scilexp";
+    "builtin-bech32-6.scilexp";
     "builtin-isqrt.scilexp";
     "builtin-eq-bystr.scilexp";
     "cons.scilexp";

tests/eval/good/builtin-bech32-6.scilexp

@@ -0,0 +1,9 @@
+let emp = Emp (Int128) (Option String) in
+let key = Int128 -3 in
+let val =
+  let str = "tzil" in
+  let addr = 0x0000000000000000000000000000000000000000
+  in builtin bystr20_to_bech32 str addr
+in
+builtin put emp key val
+

tests/eval/good/gold/builtin-bech32-6.scilexp.gold

@@ -0,0 +1,5 @@
+(Map Int128 Option (String) [((Int128 -3) => (None))]),
+{ [val -> (None)],
+  [key -> (Int128 -3)],
+  [emp -> (Map Int128 Option (String) [])] }
+Gas remaining: 4001881