[flow][enums] Fix bigint enum without explicit of bigint parsing

Summary: Changelog: [fix] Fix bigint Flow Enum without explicit `of bigint` parsing. We were previously not correctly inferring that this was a bigint enum.

Reviewed By: SamChou19815

Differential Revision: D55260671

fbshipit-source-id: 7e48e74a667c42c5d0848021abefcde370c56bb7

src/parser/enum_parser.ml

@@ -404,6 +404,7 @@ end = struct
           | None ->
             let bools_len = List.length members.boolean_members in
             let nums_len = List.length members.number_members in
+            let bigints_len = List.length members.bigint_members in
             let strs_len = List.length members.string_members in
             let defaulted_len = List.length members.defaulted_members in
             let empty () =
@@ -416,9 +417,9 @@ end = struct
                 }
             in
             begin
-              match (bools_len, nums_len, strs_len, defaulted_len) with
-              | (0, 0, 0, 0) -> empty ()
-              | (0, 0, _, _) ->
+              match (bools_len, nums_len, bigints_len, strs_len, defaulted_len) with
+              | (0, 0, 0, 0, 0) -> empty ()
+              | (0, 0, 0, _, _) ->
                 string_body
                   ~env
                   ~enum_name
@@ -427,7 +428,7 @@ end = struct
                   members.string_members
                   members.defaulted_members
                   comments
-              | (_, 0, 0, _) when bools_len >= defaulted_len ->
+              | (_, 0, 0, 0, _) when bools_len >= defaulted_len ->
                 List.iter
                   (fun (loc, { DefaultedMember.id = (_, { Identifier.name = member_name; _ }) }) ->
                     error_at
@@ -441,7 +442,7 @@ end = struct
                     has_unknown_members;
                     comments;
                   }
-              | (0, _, 0, _) when nums_len >= defaulted_len ->
+              | (0, _, 0, 0, _) when nums_len >= defaulted_len ->
                 List.iter
                   (fun (loc, { DefaultedMember.id = (_, { Identifier.name = member_name; _ }) }) ->
                     error_at
@@ -455,6 +456,20 @@ end = struct
                     has_unknown_members;
                     comments;
                   }
+              | (0, 0, _, 0, _) when bigints_len >= defaulted_len ->
+                List.iter
+                  (fun (loc, { DefaultedMember.id = (_, { Identifier.name = member_name; _ }) }) ->
+                    error_at
+                      env
+                      (loc, Parse_error.EnumNumberMemberNotInitialized { enum_name; member_name }))
+                  members.defaulted_members;
+                BigIntBody
+                  {
+                    BigIntBody.members = members.bigint_members;
+                    explicit_type = false;
+                    has_unknown_members;
+                    comments;
+                  }
               | _ ->
                 error_at env (name_loc, Parse_error.EnumInconsistentMemberValues { enum_name });
                 empty ()

tests/enums/bigint.js

@@ -2,7 +2,13 @@ enum E1 of bigint {
     A = 1n
 }
 
+E1.A as E1; // OK
+E1.A as bigint; // OK
+
 enum E2 {
     A = 1n,
     B = 2n,
 }
+
+E2.A as E2; // OK
+E2.A as bigint; // OK