Merge branch 'er433/fix/unpack-typer' into 'dev'

Fix: check that Bytes.unpack's annotated type is an option

See merge request !1245

changelog/1628516159

+author: er433
+merge_request: '1245'
+title: 'Fix: check that Bytes.unpack''s annotated type is an option'
+type: fixed

src/bin/expect_tests/contract_tests.ml

@@ -2049,3 +2049,13 @@ let%expect_test _ =
     { parameter unit ;
       storage int ;
       code { CDR ; PUSH nat 2 ; PUSH nat 1 ; DIG 2 ; ADD ; ADD ; NIL operation ; PAIR } } |}]
+
+(* wrong annotation in Bytes.unpack *)
+let%expect_test _ =
+  run_ligo_bad [ "compile-expression" ; "--init-file" ; bad_contract "bad_annotation_unpack.mligo" ; "cameligo" ; "x" ] ;
+  [%expect {|
+    File "../../test/contracts/negative/bad_annotation_unpack.mligo", line 1, characters 9-42:
+      1 | let x = (Bytes.unpack (Bytes.pack "hello") : string)
+
+    Incorrect argument.
+    Expected an option, but got an argument of type "string". |}]

src/passes/10-checking/constant_typers.ml

@@ -209,9 +209,13 @@ let int ~raise loc : typer = typer_1 ~raise loc "INT" @@ fun t ->
 let bytes_pack ~raise loc : typer = typer_1 ~raise loc "PACK" @@ fun _t ->
   t_bytes ()
 
-let bytes_unpack ~raise loc = typer_1_opt ~raise loc "UNPACK" @@ fun input output_opt ->
+let bytes_unpack ~raise loc = typer_1_opt ~raise loc "UNPACK" @@ fun input tv_opt ->
   let () = trace_option ~raise (expected_bytes loc input) @@ assert_t_bytes input in
-  trace_option ~raise (not_annotated loc) @@ output_opt
+  match tv_opt with
+  | None -> raise.raise (not_annotated loc)
+  | Some t ->
+    let t = trace_option ~raise (expected_option loc t) @@ get_t_option t in
+    t_option t
 
 let hash256 ~raise loc = typer_1 ~raise loc "SHA256" @@ fun t ->
   let () = trace_option ~raise (expected_bytes loc t) @@ assert_t_bytes t in

src/test/contracts/negative/bad_annotation_unpack.mligo

+let x = (Bytes.unpack (Bytes.pack "hello") : string)