Explicit type annotation for unit (rescript-lang#389)

* check if unit is typed

* check for Lindent _ instead of just unit

* check for type instead of just lident

* remove debug code

* added tests for ()

* added commits

* removed test.res ( which got added by mistake)

Author: a-c-sreedhar-reddy

syntax/src/res_core.ml

@@ -158,14 +158,15 @@ let getClosingToken = function
   | Lbrace -> Rbrace
   | Lbracket -> Rbracket
   | List -> Rbrace
+  | LessThan -> GreaterThan
   | _ -> assert false
 
 let rec goToClosing closingToken state =
   match (state.Parser.token, closingToken) with
-  | (Rparen, Token.Rparen) | (Rbrace, Rbrace) | (Rbracket, Rbracket) ->
+  | (Rparen, Token.Rparen) | (Rbrace, Rbrace) | (Rbracket, Rbracket) | (GreaterThan, GreaterThan) ->
     Parser.next state;
     ()
-  | (Token.Lbracket | Lparen | Lbrace | List) as t, _ ->
+  | (Token.Lbracket | Lparen | Lbrace | List | LessThan) as t, _ ->
     Parser.next state;
     goToClosing (getClosingToken t) state;
     goToClosing closingToken state
@@ -194,10 +195,32 @@ let isEs6ArrowExpression ~inTernary p =
       let prevEndPos = state.prevEndPos in
       Parser.next state;
       begin match state.token with
+      (* arrived at `()` here *)
       | Rparen ->
         Parser.next state;
         begin match state.Parser.token with
-        | Colon when not inTernary -> true
+        (* arrived at `() :` here *)
+        | Colon when not inTernary ->
+          Parser.next state;
+          begin match state.Parser.token with
+          (* arrived at `() :typ` here *)
+          | Lident _ ->
+            Parser.next state;
+            begin match state.Parser.token with
+            (* arrived at `() :typ<` here *)
+            | LessThan ->
+              Parser.next state;
+              goToClosing GreaterThan state;
+            | _ -> ()
+            end;
+            begin match state.Parser.token with
+            (* arrived at `() :typ =>` or `() :typ<'a,'b> =>` here *)
+            | EqualGreater ->
+              true
+            | _ -> false
+            end
+          | _ -> true
+          end
         | EqualGreater -> true
         | _ -> false
         end

syntax/tests/parsing/grammar/expressions/arrow.res

@@ -96,3 +96,15 @@ let x = Constructore(_ => copyChecklistItemCB(), _ => copyChecklistItemCB())
 let y = #Constructore(_ => copyChecklistItemCB(), _ => copyChecklistItemCB())
 
 let f = (list) => list + 1
+
+let foo = ((): unit)
+
+type u = unit
+let un = (():u)
+
+type d<'a,'b> = ('a,'b)
+let c = (): d<'a,'b> => (1,2)
+
+let fn = f => f;
+type f = int => unit;
+let a = fn(_ => (): f);

syntax/tests/parsing/grammar/expressions/expected/arrow.res.txt

@@ -77,4 +77,12 @@ let x =
 let y =
   `Constructore
     ((fun _ -> copyChecklistItemCB ()), (fun _ -> copyChecklistItemCB ()))
-let f list = list + 1
+let f list = list + 1
+let foo = (() : unit)
+type nonrec u = unit
+let un = (() : u)
+type nonrec ('a, 'b) d = ('a * 'b)
+let c () = ((1, 2) : ('a, 'b) d)
+let fn f = f
+type nonrec f = int -> unit
+let a = fn (fun _ -> () : f)