await AST node for expressions (#7368)

* wip: await AST

* Restore ast ppx test.

* cleanup

* Clean up `cli.bsc.js` invocation and mentions.

* final cleanup

Author: cristianoc

CHANGELOG.md

@@ -25,6 +25,7 @@
 - Remove `Stdlib_Char` module for now. https://github.com/rescript-lang/rescript/pull/7367
 - Convert internal JavaScript codebase into ESM, ReScript package itself is now ESM (`"type": "module"`). https://github.com/rescript-lang/rescript/pull/6899
 - Add built-in support for the JavaScript `in` operator. https://github.com/rescript-lang/rescript/pull/7342
+- AST cleanup: add `Pexp_await` ast node instead of `res.await` attribute. (The attribute is still used for await on modules currently). https://github.com/rescript-lang/rescript/pull/7368
 
 #### :nail_care: Polish
 

CONTRIBUTING.md

@@ -123,19 +123,19 @@ After adding a new file to the repository that should go into the npm package -
 
 ```sh
 make lib # Build compiler and standard library
-./cli/bsc myTestFile.res
+./cli/bsc.js myTestFile.res
 ```
 
 To view the untyped tree of the file run:
 
 ```sh
-./cli/bsc -dparsetree myTestFile.res
+./cli/bsc.js -dparsetree myTestFile.res
 ```
 
 To view the typed tree of the file run:
 
 ```sh
-./cli/bsc -dtypedtree myTestFile.res
+./cli/bsc.js -dtypedtree myTestFile.res
 ```
 
 ### Project

analysis/src/CompletionFrontEnd.ml

@@ -312,11 +312,12 @@ let rec exprToContextPathInner ~(inJsxContext : bool) (e : Parsetree.expression)
     if List.length exprs = List.length exprsAsContextPaths then
       Some (CTuple exprsAsContextPaths)
     else None
+  | Pexp_await e -> exprToContextPathInner ~inJsxContext e
   | _ -> None
 
 and exprToContextPath ~(inJsxContext : bool) (e : Parsetree.expression) =
   match
-    ( Res_parsetree_viewer.has_await_attribute e.pexp_attributes,
+    ( Res_parsetree_viewer.expr_is_await e,
       exprToContextPathInner ~inJsxContext e )
   with
   | true, Some ctxPath -> Some (CPAwait ctxPath)

analysis/src/Utils.ml

@@ -111,6 +111,7 @@ let identifyPexp pexp =
   | Pexp_pack _ -> "Pexp_pack"
   | Pexp_extension _ -> "Pexp_extension"
   | Pexp_open _ -> "Pexp_open"
+  | Pexp_await _ -> "Pexp_await"
 
 let identifyPpat pat =
   match pat with

compiler/frontend/bs_ast_mapper.ml

@@ -366,6 +366,7 @@ module E = struct
     | Pexp_open (ovf, lid, e) ->
       open_ ~loc ~attrs ovf (map_loc sub lid) (sub.expr sub e)
     | Pexp_extension x -> extension ~loc ~attrs (sub.extension sub x)
+    | Pexp_await e -> await ~loc ~attrs (sub.expr sub e)
 end
 
 module P = struct

compiler/frontend/bs_builtin_ppx.ml

@@ -242,10 +242,12 @@ let expr_mapper ~async_context ~in_function_def (self : mapper)
          || Ast_attributes.has_await_payload attrs2 ->
     check_await ();
     result
-  | _ when Ast_attributes.has_await_payload e.pexp_attributes ->
-    check_await ();
-    Ast_await.create_await_expression result
-  | _ -> result
+  | _ -> (
+    match result.pexp_desc with
+    | Pexp_await e ->
+      check_await ();
+      Ast_await.create_await_expression e
+    | _ -> result)
 
 let typ_mapper (self : mapper) (typ : Parsetree.core_type) =
   Ast_core_type_class_type.typ_mapper self typ

compiler/ml/ast_helper.ml

@@ -180,7 +180,7 @@ module Exp = struct
   let pack ?loc ?attrs a = mk ?loc ?attrs (Pexp_pack a)
   let open_ ?loc ?attrs a b c = mk ?loc ?attrs (Pexp_open (a, b, c))
   let extension ?loc ?attrs a = mk ?loc ?attrs (Pexp_extension a)
-
+  let await ?loc ?attrs a = mk ?loc ?attrs (Pexp_await a)
   let case lhs ?guard rhs = {pc_lhs = lhs; pc_guard = guard; pc_rhs = rhs}
 end
 

compiler/ml/ast_helper.mli

@@ -210,6 +210,7 @@ module Exp : sig
   val extension : ?loc:loc -> ?attrs:attrs -> extension -> expression
 
   val case : pattern -> ?guard:expression -> expression -> case
+  val await : ?loc:loc -> ?attrs:attrs -> expression -> expression
 end
 
 (** Value declarations *)

compiler/ml/ast_iterator.ml

@@ -344,6 +344,7 @@ module E = struct
       iter_loc sub lid;
       sub.expr sub e
     | Pexp_extension x -> sub.extension sub x
+    | Pexp_await e -> sub.expr sub e
 end
 
 module P = struct

compiler/ml/ast_mapper.ml

@@ -329,6 +329,7 @@ module E = struct
     | Pexp_open (ovf, lid, e) ->
       open_ ~loc ~attrs ovf (map_loc sub lid) (sub.expr sub e)
     | Pexp_extension x -> extension ~loc ~attrs (sub.extension sub x)
+    | Pexp_await e -> await ~loc ~attrs (sub.expr sub e)
 end
 
 module P = struct

compiler/ml/ast_mapper_from0.ml

@@ -295,11 +295,30 @@ end
 module E = struct
   (* Value expressions for the core language *)
 
-  let map sub {pexp_loc = loc; pexp_desc = desc; pexp_attributes = attrs} =
+  let has_await_attribute attrs =
+    List.exists
+      (function
+        | {Location.txt = "res.await"}, _ -> true
+        | _ -> false)
+      attrs
+
+  let remove_await_attribute attrs =
+    List.filter
+      (function
+        | {Location.txt = "res.await"}, _ -> false
+        | _ -> true)
+      attrs
+
+  let map sub ({pexp_loc = loc; pexp_desc = desc; pexp_attributes = attrs} as e)
+      =
     let open Exp in
     let loc = sub.location sub loc in
     let attrs = sub.attributes sub attrs in
     match desc with
+    | _ when has_await_attribute attrs ->
+      let attrs = remove_await_attribute e.pexp_attributes in
+      let e = sub.expr sub {e with pexp_attributes = attrs} in
+      await ~loc e
     | Pexp_ident x -> ident ~loc ~attrs (map_loc sub x)
     | Pexp_constant x -> constant ~loc ~attrs (map_constant x)
     | Pexp_let (r, vbs, e) ->

compiler/ml/ast_mapper_to0.ml

@@ -407,6 +407,13 @@ module E = struct
     | Pexp_open (ovf, lid, e) ->
       open_ ~loc ~attrs ovf (map_loc sub lid) (sub.expr sub e)
     | Pexp_extension x -> extension ~loc ~attrs (sub.extension sub x)
+    | Pexp_await e ->
+      let e = sub.expr sub e in
+      {
+        e with
+        pexp_attributes =
+          (Location.mknoloc "res.await", Pt.PStr []) :: e.pexp_attributes;
+      }
 end
 
 module P = struct

compiler/ml/ast_uncurried.ml

@@ -19,8 +19,3 @@ let expr_is_uncurried_fun (expr : Parsetree.expression) =
   match expr.pexp_desc with
   | Pexp_fun {arity = Some _} -> true
   | _ -> false
-
-let expr_extract_uncurried_fun (expr : Parsetree.expression) =
-  match expr.pexp_desc with
-  | Pexp_fun {arity = Some _} -> expr
-  | _ -> assert false

compiler/ml/depend.ml

@@ -289,6 +289,7 @@ let rec add_expr bv exp =
     | Pstr_eval ({pexp_desc = Pexp_construct (c, None)}, _) -> add bv c
     | _ -> handle_extension e)
   | Pexp_extension e -> handle_extension e
+  | Pexp_await e -> add_expr bv e
 
 and add_cases bv cases = List.iter (add_case bv) cases
 

compiler/ml/parsetree.ml

@@ -313,8 +313,9 @@ and expression_desc =
        let open M in E
        let! open M in E *)
   | Pexp_extension of extension
-(* [%id] *)
-(* . *)
+  (* [%id] *)
+  (* . *)
+  | Pexp_await of expression
 
 and case = {
   (* (P -> E) or (P when E0 -> E) *)

compiler/ml/pprintast.ml

@@ -722,6 +722,7 @@ and expression ctxt f x =
         (expression ctxt) e
     | Pexp_variant (l, Some eo) -> pp f "@[<2>`%s@;%a@]" l (simple_expr ctxt) eo
     | Pexp_extension e -> extension ctxt f e
+    | Pexp_await e -> pp f "@[<hov2>await@ %a@]" (simple_expr ctxt) e
     | _ -> expression1 ctxt f x
 
 and expression1 ctxt f x =

compiler/ml/printast.ml

@@ -345,6 +345,9 @@ and expression i ppf x =
   | Pexp_extension (s, arg) ->
     line i ppf "Pexp_extension \"%s\"\n" s.txt;
     payload i ppf arg
+  | Pexp_await e ->
+    line i ppf "Pexp_await\n";
+    expression i ppf e
 
 and value_description i ppf x =
   line i ppf "value_description %a %a\n" fmt_string_loc x.pval_name fmt_location

compiler/ml/typecore.ml

@@ -178,6 +178,7 @@ let iter_expression f e =
       expr e;
       module_expr me
     | Pexp_pack me -> module_expr me
+    | Pexp_await _ -> assert false (* should be handled earlier *)
   and case {pc_lhs = _; pc_guard; pc_rhs} =
     may expr pc_guard;
     expr pc_rhs
@@ -3195,6 +3196,7 @@ and type_expect_ ?type_clash_context ?in_function ?(recarg = Rejected) env sexp
     | _ -> raise (Error (loc, env, Invalid_extension_constructor_payload)))
   | Pexp_extension ext ->
     raise (Error_forward (Builtin_attributes.error_of_extension ext))
+  | Pexp_await _ -> (* should be handled earlier *) assert false
 
 and type_function ?in_function ~arity ~async loc attrs env ty_expected_ l
     caselist =

compiler/syntax/src/res_ast_debugger.ml

@@ -707,6 +707,7 @@ module SexpAst = struct
           ]
       | Pexp_extension ext ->
         Sexp.list [Sexp.atom "Pexp_extension"; extension ext]
+      | Pexp_await e -> Sexp.list [Sexp.atom "Pexp_await"; expression e]
     in
     Sexp.list [Sexp.atom "expression"; desc]
 

compiler/syntax/src/res_core.ml

@@ -3307,15 +3307,12 @@ and parse_async_arrow_expression ?(arrow_attrs = []) p =
 
 and parse_await_expression p =
   let await_loc = mk_loc p.Parser.start_pos p.end_pos in
-  let await_attr = make_await_attr await_loc in
   Parser.expect Await p;
   let token_prec = Token.precedence MinusGreater in
   let expr = parse_binary_expr ~context:OrdinaryExpr p token_prec in
-  {
-    expr with
-    pexp_attributes = await_attr :: expr.pexp_attributes;
-    pexp_loc = {expr.pexp_loc with loc_start = await_loc.loc_start};
-  }
+  Ast_helper.Exp.await
+    ~loc:{expr.pexp_loc with loc_start = await_loc.loc_start}
+    ~attrs:[] expr
 
 and parse_try_expression p =
   let start_pos = p.Parser.start_pos in

compiler/syntax/src/res_parens.ml

@@ -56,8 +56,7 @@ let call_expr expr =
     } ->
       Parenthesized
     | _ when Ast_uncurried.expr_is_uncurried_fun expr -> Parenthesized
-    | _ when ParsetreeViewer.has_await_attribute expr.pexp_attributes ->
-      Parenthesized
+    | _ when ParsetreeViewer.expr_is_await expr -> Parenthesized
     | _ -> Nothing)
 
 let structure_expr expr =
@@ -109,8 +108,7 @@ let unary_expr_operand expr =
        | Pexp_try _ | Pexp_while _ | Pexp_for _ | Pexp_ifthenelse _ );
     } ->
       Parenthesized
-    | _ when ParsetreeViewer.has_await_attribute expr.pexp_attributes ->
-      Parenthesized
+    | _ when ParsetreeViewer.expr_is_await expr -> Parenthesized
     | _ -> Nothing)
 
 let binary_expr_operand ~is_lhs expr =
@@ -133,8 +131,7 @@ let binary_expr_operand ~is_lhs expr =
     | expr when ParsetreeViewer.is_binary_expression expr -> Parenthesized
     | expr when ParsetreeViewer.is_ternary_expr expr -> Parenthesized
     | {pexp_desc = Pexp_lazy _ | Pexp_assert _} when is_lhs -> Parenthesized
-    | _ when ParsetreeViewer.has_await_attribute expr.pexp_attributes ->
-      Parenthesized
+    | _ when ParsetreeViewer.expr_is_await expr -> Parenthesized
     | {Parsetree.pexp_attributes = attrs} ->
       if ParsetreeViewer.has_printable_attributes attrs then Parenthesized
       else Nothing)
@@ -229,9 +226,7 @@ let lazy_or_assert_or_await_expr_rhs ?(in_await = false) expr =
        | Pexp_while _ | Pexp_for _ | Pexp_ifthenelse _ );
     } ->
       Parenthesized
-    | _
-      when (not in_await)
-           && ParsetreeViewer.has_await_attribute expr.pexp_attributes ->
+    | _ when (not in_await) && ParsetreeViewer.expr_is_await expr ->
       Parenthesized
     | _ -> Nothing)
 
@@ -277,8 +272,7 @@ let field_expr expr =
        | Pexp_try _ | Pexp_while _ | Pexp_for _ | Pexp_ifthenelse _ );
     } ->
       Parenthesized
-    | _ when ParsetreeViewer.has_await_attribute expr.pexp_attributes ->
-      Parenthesized
+    | _ when ParsetreeViewer.expr_is_await expr -> Parenthesized
     | _ -> Nothing)
 
 let set_field_expr_rhs expr =
@@ -339,8 +333,7 @@ let jsx_prop_expr expr =
       }
         when starts_with_minus x ->
         Parenthesized
-      | _ when ParsetreeViewer.has_await_attribute expr.pexp_attributes ->
-        Parenthesized
+      | _ when ParsetreeViewer.expr_is_await expr -> Parenthesized
       | {
        Parsetree.pexp_desc =
          ( Pexp_ident _ | Pexp_constant _ | Pexp_field _ | Pexp_construct _
@@ -377,8 +370,7 @@ let jsx_child_expr expr =
       }
         when starts_with_minus x ->
         Parenthesized
-      | _ when ParsetreeViewer.has_await_attribute expr.pexp_attributes ->
-        Parenthesized
+      | _ when ParsetreeViewer.expr_is_await expr -> Parenthesized
       | {
        Parsetree.pexp_desc =
          ( Pexp_ident _ | Pexp_constant _ | Pexp_field _ | Pexp_construct _

compiler/syntax/src/res_parsetree_viewer.ml

@@ -72,6 +72,11 @@ let has_await_attribute attrs =
       | _ -> false)
     attrs
 
+let expr_is_await e =
+  match e.pexp_desc with
+  | Pexp_await _ -> true
+  | _ -> false
+
 let has_inline_record_definition_attribute attrs =
   List.exists
     (function
@@ -111,12 +116,7 @@ let collect_list_expressions expr =
 
 (* (__x) => f(a, __x, c) -----> f(a, _, c)  *)
 let rewrite_underscore_apply expr =
-  let expr_fun =
-    if Ast_uncurried.expr_is_uncurried_fun expr then
-      Ast_uncurried.expr_extract_uncurried_fun expr
-    else expr
-  in
-  match expr_fun.pexp_desc with
+  match expr.pexp_desc with
   | Pexp_fun
       {
         arg_label = Nolabel;

compiler/syntax/src/res_parsetree_viewer.mli

@@ -14,6 +14,7 @@ val functor_type :
   list
   * Parsetree.module_type
 
+val expr_is_await : Parsetree.expression -> bool
 val has_await_attribute : Parsetree.attributes -> bool
 val has_inline_record_definition_attribute : Parsetree.attributes -> bool
 val has_res_pat_variant_spread_attribute : Parsetree.attributes -> bool