rework error when comparing two sum types

src/bin/expect_tests/typer_error_tests.ml

@@ -253,3 +253,21 @@ let%expect_test _ =
     * Ask a question on our Discord: https://discord.gg/9rhYaEt
     * Open a gitlab issue: https://gitlab.com/ligolang/ligo/issues/new
     * Check the changelog by running 'ligo changelog' |}]
+
+let%expect_test _ =
+  run_ligo_bad [ "compile-contract" ; "../../test/contracts/negative/compare_sum_types.ligo" ; "main" ] ;
+  [%expect {|
+    ligo: error
+    in file "compare_sum_types.ligo", line 3, characters 9-13
+    Constant declaration 'main'
+    Those two types are not comparable:
+    - sum[Bar -> unit , Foo -> unit]
+    - sum[Bar -> unit , Foo -> unit]
+
+
+    If you're not sure how to fix this error, you can do one of the following:
+
+    * Visit our documentation: https://ligolang.org/docs/intro/introduction
+    * Ask a question on our Discord: https://discord.gg/9rhYaEt
+    * Open a gitlab issue: https://gitlab.com/ligolang/ligo/issues/new
+    * Check the changelog by running 'ligo changelog' |}]

src/passes/09-typing/08-typer-common/constant_typers.ml

@@ -652,7 +652,7 @@ let rec pair_comparator : string -> typer = fun s -> typer_2 s @@ fun a b ->
   comparator s [a_v;b_v] None
     
 and comparator : string -> typer = fun s -> typer_2 s @@ fun a b ->
-  bind_or (simple_comparator s [a;b] None, pair_comparator s [a;b] None)
+  bind_or (pair_comparator s [a;b] None, simple_comparator s [a;b] None)
 
 let constant_typers c : (typer , typer_error) result = match c with
   | C_INT                 -> ok @@ int ;

src/passes/09-typing/08-typer-common/errors.ml

@@ -447,10 +447,8 @@ let rec error_ppformat : display_format:string display_format ->
       Ast_typed.PP.type_expression t
     | `Typer_uncomparable_types (a,b) ->
       Format.fprintf f
-        "@[<hv>Those two types are not comparable:@ %a - %a@ %a - %a@]"
-      Location.pp a.location
+        "@[<hv>Those two types are not comparable:@ - %a@ - %a@]"
       Ast_typed.PP.type_expression a
-      Location.pp b.location
       Ast_typed.PP.type_expression b
     | `Typer_comparator_composed a ->
       Format.fprintf f

src/test/contracts/negative/compare_sum_types.ligo

@@ -0,0 +1,4 @@
+type foo is Foo | Bar
+
+function main (const p : foo; const s : bool) : list(operation) * bool is
+  ((nil : list (operation)), p = Foo)