Js-parser: add support for for await (#1550)

* Compiler: js-parser support for await

* Changes

CHANGES.md

@@ -2,12 +2,14 @@
 
 ## Features/Changes
 * Compiler: try to preserve clorures ordering between ml and js
+* Compiler: js-parser accept for await
 
 ## Bug fixes
 * Compiler: js-parser now accept all the line terminators defined in the spec
 * Compiler: js-parser: fix support for LHS assignment target
 * Compiler: js-parser: fix parser of default export
 * Compiler: js-parser: allow 'as' as ident
+* Compiler: js-parser: fix for in rewriting
 
 # 5.5.2 (2023-12-01) - Lille
 

compiler/lib/javascript.ml

@@ -336,6 +336,10 @@ and statement =
       (expression, variable_declaration_kind * for_binding) either
       * expression
       * (statement * location)
+  | ForAwaitOf_statement of
+      (expression, variable_declaration_kind * for_binding) either
+      * expression
+      * (statement * location)
   | Continue_statement of Label.t option
   | Break_statement of Label.t option
   | Return_statement of expression option

compiler/lib/javascript.mli

@@ -254,6 +254,10 @@ and statement =
       (expression, variable_declaration_kind * for_binding) either
       * expression
       * (statement * location)
+  | ForAwaitOf_statement of
+      (expression, variable_declaration_kind * for_binding) either
+      * expression
+      * (statement * location)
   | Continue_statement of Label.t option
   | Break_statement of Label.t option
   | Return_statement of expression option

compiler/lib/js_output.ml

@@ -275,6 +275,7 @@ struct
     | For_statement (_, _, _, st)
     | ForIn_statement (_, _, st) -> ends_with_if_without_else st
     | ForOf_statement (_, _, st) -> ends_with_if_without_else st
+    | ForAwaitOf_statement (_, _, st) -> ends_with_if_without_else st
     | If_statement (_, _, None) -> true
     | Block _
     | Variable_statement _
@@ -1313,6 +1314,28 @@ struct
         PP.end_group f;
         statement1 ~last f s;
         PP.end_group f
+    | ForAwaitOf_statement (e1, e2, s) ->
+        PP.start_group f 0;
+        PP.start_group f 0;
+        PP.string f "for await";
+        PP.break f;
+        PP.start_group f 1;
+        PP.string f "(";
+        (match e1 with
+        | Left e ->
+            (* Should not starts with "let" *)
+            parenthesized_expression ~let_identifier:true Expression f e
+        | Right (k, v) -> for_binding f k v);
+        PP.space f;
+        PP.string f "of";
+        PP.break f;
+        PP.space f;
+        expression Expression f e2;
+        PP.string f ")";
+        PP.end_group f;
+        PP.end_group f;
+        statement1 ~last f s;
+        PP.end_group f
     | Continue_statement None ->
         PP.string f "continue";
         last_semi ()

compiler/lib/js_parser.mly

@@ -713,6 +713,11 @@ iteration_stmt:
       ForOf_statement (Left left, right, body) }
  | T_FOR "(" left=for_single_variable_decl T_OF right=assignment_expr ")" body=stmt
    { ForOf_statement (Right left, right, body) }
+ | T_FOR T_AWAIT "(" left=left_hand_side_expr T_OF right=assignment_expr ")" body=stmt
+    { let left = assignment_target_of_expr None left in
+      ForAwaitOf_statement (Left left, right, body) }
+ | T_FOR T_AWAIT "(" left=for_single_variable_decl T_OF right=assignment_expr ")" body=stmt
+   { ForAwaitOf_statement (Right left, right, body) }
 
 initializer_no_in:
  | "=" e=assignment_expr_no_in { e, p $symbolstartpos }

compiler/lib/js_simpl.ml

@@ -160,6 +160,7 @@ let rec depth = function
   | For_statement (_, _, _, (s, _)) -> depth s + 1
   | ForIn_statement (_, _, (s, _)) -> depth s + 1
   | ForOf_statement (_, _, (s, _)) -> depth s + 1
+  | ForAwaitOf_statement (_, _, (s, _)) -> depth s + 1
   | Continue_statement _ -> 1
   | Break_statement _ -> 1
   | Return_statement _ -> 1

compiler/lib/js_traverse.ml

@@ -176,6 +176,13 @@ class map : mapper =
             | Right (k, d) -> Right (k, m#for_binding k d)
           in
           ForOf_statement (e1, m#expression e2, (m#statement s, m#loc loc))
+      | ForAwaitOf_statement (e1, e2, (s, loc)) ->
+          let e1 =
+            match e1 with
+            | Left e -> Left (m#expression e)
+            | Right (k, d) -> Right (k, m#for_binding k d)
+          in
+          ForAwaitOf_statement (e1, m#expression e2, (m#statement s, m#loc loc))
       | Continue_statement s -> Continue_statement s
       | Break_statement s -> Break_statement s
       | Return_statement e -> Return_statement (m#expression_o e)
@@ -516,7 +523,12 @@ class iter : iterator =
           (match e1 with
           | Left e -> m#expression e
           | Right (k, d) -> m#for_binding k d);
-
+          m#expression e2;
+          m#statement s
+      | ForAwaitOf_statement (e1, e2, (s, _)) ->
+          (match e1 with
+          | Left e -> m#expression e
+          | Right (k, d) -> m#for_binding k d);
           m#expression e2;
           m#statement s
       | Continue_statement _ -> ()
@@ -1063,6 +1075,15 @@ class free =
           m'#record_block Normal;
           m#merge_block_info m';
           ForOf_statement (Right (k, l), e2, (st, m#loc loc))
+      | ForAwaitOf_statement (Right (((Const | Let) as k), l), e2, (st, loc)) ->
+          let same_level = level in
+          let m' = {<state_ = empty; level = same_level>} in
+          let l = m'#for_binding k l in
+          let e2 = m'#expression e2 in
+          let st = m'#statement st in
+          m'#record_block Normal;
+          m#merge_block_info m';
+          ForAwaitOf_statement (Right (k, l), e2, (st, m#loc loc))
       | Switch_statement (e, l, def, l') ->
           let same_level = level in
           let m' = {<state_ = empty; level = same_level>} in
@@ -1186,6 +1207,10 @@ class rename_variable ~esm =
              let m = {<depth = depth + 1>} in
              m#for_binding k l;
              m#statement st
+         | _, ForAwaitOf_statement (Right (((Const | Let) as k), l), _e2, (st, _loc)) ->
+             let m = {<depth = depth + 1>} in
+             m#for_binding k l;
+             m#statement st
          | _, ForIn_statement (Right (((Const | Let) as k), l), _e2, (st, _loc)) ->
              let m = {<depth = depth + 1>} in
              m#for_binding k l;
@@ -1352,10 +1377,17 @@ class rename_variable ~esm =
             ( Right (k, m'#for_binding k l)
             , m'#expression e2
             , (m'#statement st, m'#loc loc) )
+      | ForAwaitOf_statement (Right (((Const | Let) as k), l), e2, (st, loc)) ->
+          let ids = bound_idents_of_binding l in
+          let m' = m#update_state Lexical_block ids [] in
+          ForAwaitOf_statement
+            ( Right (k, m'#for_binding k l)
+            , m'#expression e2
+            , (m'#statement st, m'#loc loc) )
       | ForIn_statement (Right (((Const | Let) as k), l), e2, (st, loc)) ->
           let ids = bound_idents_of_binding l in
           let m' = m#update_state Lexical_block ids [] in
-          ForOf_statement
+          ForIn_statement
             ( Right (k, m'#for_binding k l)
             , m'#expression e2
             , (m'#statement st, m'#loc loc) )
@@ -1632,6 +1664,7 @@ class clean =
       | For_statement (p1, p2, p3, st) -> For_statement (p1, p2, p3, b st)
       | ForIn_statement (param, e, st) -> ForIn_statement (param, e, b st)
       | ForOf_statement (param, e, st) -> ForOf_statement (param, e, b st)
+      | ForAwaitOf_statement (param, e, st) -> ForAwaitOf_statement (param, e, b st)
       | Switch_statement (e, l, Some [], []) -> Switch_statement (e, l, None, [])
       | s -> s
   end

compiler/tests-compiler/js_parser_printer.ml

@@ -451,6 +451,27 @@ let%expect_test "assignment pattern" =
     /*<<fake:17:4>>*/ for([a, b, {c, d = e, [f]: [g, h, a, i, j]}] of 3)
      /*<<fake:17:43>>*/ ; |}]
 
+let%expect_test "for loops" =
+  (* GH#1017 *)
+  print
+    ~report:true
+    ~compact:false
+    {|
+    for(x in 3);
+    for(x of 3);
+    async function f(x) {
+    for await(x of 3);
+    }
+ |};
+
+  [%expect
+    {|
+    /*<<fake:2:4>>*/ for(x in 3)  /*<<fake:2:15>>*/ ;
+    /*<<fake:3:4>>*/ for(x of 3)  /*<<fake:3:15>>*/ ;
+    /*<<fake:4:4>>*/ async function f(x){
+     /*<<fake:5:4>>*/ for await(x of 3)  /*<<fake:5:21>>*/ ;
+    /*<<fake:4:4>>*/ } |}]
+
 let%expect_test "string template" =
   (* GH#1017 *)
   print

compiler/tests-compiler/scopes.ml

@@ -79,7 +79,7 @@ let%expect_test "let inside forin" =
       1: (function(){
       2:    let v2 = 2;
       3:    var v3 = 0, v1 = [1, 2, 3];
-      4:    for(let v4 of v1){console.log(v4); v3 += v1[v4];}
+      4:    for(let v4 in v1){console.log(v4); v3 += v1[v4];}
       5:    console.log(v3);
       6:    console.log(v2);
       7:   }
@@ -121,6 +121,31 @@ let%expect_test "let inside forof" =
     6
     2 |}]
 
+let%expect_test "let inside forawaitof" =
+  test
+    {|
+async function f () {
+  let x = 2
+  var y = 0;
+  for await(let x of [1,2,3]) {
+    console.log(x);
+    y += x;
+  }
+  console.log(y);
+  console.log(x);
+}
+|};
+  [%expect
+    {|
+    $ cat "test.min.js"
+      1: async function f(){
+      2:  let v1 = 2;
+      3:  var v2 = 0;
+      4:  for await(let v3 of [1, 2, 3]){console.log(v3); v2 += v3;}
+      5:  console.log(v2);
+      6:  console.log(v1);
+      7: } |}]
+
 let%expect_test "let inside switch" =
   test
     {|