share a few definitions

Author: zth

jscomp/build_tests/super_errors/expected/dict_coercion.res.expected

@@ -2,7 +2,7 @@
   We've found a bug for you!
   /.../fixtures/dict_coercion.res:7:10-30
 
-  5 │ type fakeDict<'t> = {anyOtherField?: 't}
+  5 │ type fakeDict<'t> = {dictValuesType?: 't}
   6 │ 
   7 │ let d = (dict :> fakeDict<int>)
   8 │ 

jscomp/build_tests/super_errors/expected/dict_pattern_inference_constrained.res.expected

@@ -8,7 +8,7 @@
   4 │     let _: dict<string> = dict
   5 │     Js.log("one")
 
-  the following labels are not bound in this record pattern: anyOtherField
+  the following labels are not bound in this record pattern: dictValuesType
 Either bind these labels explicitly or add ', _' to the pattern.
 
 

jscomp/build_tests/super_errors/fixtures/dict_coercion.res

@@ -2,6 +2,6 @@ let dict = Js.Dict.empty()
 dict->Js.Dict.set("someKey1", 1)
 dict->Js.Dict.set("someKey2", 2)
 
-type fakeDict<'t> = {anyOtherField?: 't}
+type fakeDict<'t> = {dictValuesType?: 't}
 
 let d = (dict :> fakeDict<int>)

jscomp/build_tests/super_errors/fixtures/dict_magic_field_on_non_dict.res

@@ -1,4 +1,4 @@
-type fakeDict<'t> = {anyOtherField?: 't}
+type fakeDict<'t> = {dictValuesType?: 't}
 
 let foo = (fakeDict: fakeDict<'a>) => {
   switch fakeDict {

jscomp/ml/dict_type_helpers.ml

@@ -1,3 +1,5 @@
+let dict_magic_field_name = "dictValuesType"
+
 let has_dict_pattern_attribute attrs =
   attrs
   |> List.find_opt (fun (({txt}, _) : Parsetree.attribute) ->
@@ -6,5 +8,11 @@ let has_dict_pattern_attribute attrs =
 
 let has_dict_attribute attrs =
   attrs
-  |> List.find_opt (fun (({txt}, _) : Parsetree.attribute) -> txt = "res.dict")
-  |> Option.is_some
+  |> List.find_opt (fun (({txt}, _) : Parsetree.attribute) -> txt = "res.$dict")
+  |> Option.is_some
+
+let dict_attr : Parsetree.attribute =
+  (Location.mknoloc "res.$dict", Parsetree.PStr [])
+
+let dict_magic_field_attr : Parsetree.attribute =
+  (Location.mknoloc "res.$dictMagicField", Parsetree.PStr [])

jscomp/ml/predef.ml

@@ -112,7 +112,7 @@ and ident_failure = ident_create_predef_exn "Failure"
 and ident_ok = ident_create_predef_exn "Ok"
 and ident_error = ident_create_predef_exn "Error"
 
-and ident_anyOtherField = ident_create "anyOtherField"
+and ident_dict_magic_field_name = ident_create Dict_type_helpers.dict_magic_field_name
 
 and ident_js_error = ident_create_predef_exn "JsError"
 and ident_not_found = ident_create_predef_exn "Not_found"
@@ -220,19 +220,24 @@ let common_initial_env add_type add_extension empty_env =
      type_variance = [Variance.covariant; Variance.covariant]}
   and decl_dict =
     let tvar = newgenvar() in
+    (* Dicts are implented as a as a single "magic" field record. This magic field
+       is then leveraged to be able to piggy back on the existing record pattern
+       matching mechanism. So, this definition is import for the dict pattern
+       matching functionality, but not something intended to be exposed to the
+       user. *) 
     {decl_abstr with
-      type_attributes = [(Location.mknoloc "res.dict", Parsetree.PStr [])];
+      type_attributes = [Dict_type_helpers.dict_attr];
       type_params = [tvar];
       type_arity = 1;
       type_variance = [Variance.full];
       type_kind = Type_record ([{
-          ld_id = ident_anyOtherField;
-          ld_attributes = [(Location.mknoloc "res.optional", Parsetree.PStr []); (Location.mknoloc "res.dictMagicField", Parsetree.PStr [])];
+          ld_id = ident_dict_magic_field_name;
+          ld_attributes = [(Location.mknoloc "res.optional", Parsetree.PStr []); Dict_type_helpers.dict_magic_field_attr];
           ld_loc = Location.none;
           ld_mutable = Immutable; (* TODO(dict-pattern-matching) Should probably be mutable? *) 
           ld_type = newgenty (Tconstr (path_option, [tvar], ref Mnil));
         }], 
-        Record_optional_labels [Ident.name ident_anyOtherField]);
+        Record_optional_labels [Ident.name ident_dict_magic_field_name]);
     }
   and decl_uncurried =
     let tvar1, tvar2 = newgenvar(), newgenvar() in

jscomp/ml/typecore.ml

@@ -811,12 +811,12 @@ end) = struct
         Longident.Lident s_ -> begin
           let s = 
             if List.exists (fun nd -> get_name nd = s_) descrs
-            || not (List.exists (fun nd -> get_name nd = "anyOtherField") descrs)
+            || not (List.exists (fun nd -> get_name nd = Dict_type_helpers.dict_magic_field_name) descrs)
             then s_
-            else "anyOtherField" in 
+            else Dict_type_helpers.dict_magic_field_name in 
           try
             let x = List.find (fun nd -> get_name nd = s) descrs in
-            if s = "anyOtherField"
+            if s = Dict_type_helpers.dict_magic_field_name
               then add_with_name x s_
               else x
           with Not_found ->