Only store res.async attribute on function nodes.

Author: cristianoc

compiler/ml/ast_async.ml

@@ -1,6 +1,12 @@
 let has_async_payload attrs =
   Ext_list.exists attrs (fun ({Location.txt}, _) -> txt = "res.async")
 
+let rec dig_async_payload_from_function (expr : Parsetree.expression) =
+  match expr.pexp_desc with
+  | Pexp_fun _ -> has_async_payload expr.pexp_attributes
+  | Pexp_newtype (_, body) -> dig_async_payload_from_function body
+  | _ -> false
+
 let add_async_attribute ~async (body : Parsetree.expression) =
   let add (exp : Parsetree.expression) =
     if has_async_payload exp.pexp_attributes then exp
@@ -20,7 +26,7 @@ let add_async_attribute ~async (body : Parsetree.expression) =
       | Pexp_fun _ -> add exp
       | _ -> exp
     in
-    add (add_to_fun body)
+    add_to_fun body
   else body
 
 let add_promise_type ?(loc = Location.none) ~async

compiler/syntax/src/jsx_v4.ml

@@ -954,9 +954,7 @@ let map_binding ~config ~empty_loc ~pstr_loc ~file_name ~rec_flag binding =
     let binding_wrapper, has_forward_ref, expression =
       modified_binding ~binding_loc ~binding_pat_loc ~fn_name binding
     in
-    let is_async =
-      Ast_async.has_async_payload binding.pvb_expr.pexp_attributes
-    in
+    let is_async = Ast_async.dig_async_payload_from_function binding.pvb_expr in
     let named_arg_list, newtypes, _typeConstraints =
       recursively_transform_named_args_for_make
         (modified_binding_old binding)
@@ -1190,7 +1188,7 @@ let map_binding ~config ~empty_loc ~pstr_loc ~file_name ~rec_flag binding =
     in
 
     let is_async =
-      Ast_async.has_async_payload modified_binding.pvb_expr.pexp_attributes
+      Ast_async.dig_async_payload_from_function modified_binding.pvb_expr
     in
 
     let make_new_binding ~loc ~full_module_name binding =

compiler/syntax/src/res_parsetree_viewer.ml

@@ -166,7 +166,7 @@ type fun_param_kind =
   | NewTypes of {attrs: Parsetree.attributes; locs: string Asttypes.loc list}
 
 let fun_expr expr_ =
-  let async = Ast_async.has_async_payload expr_.pexp_attributes in
+  let async = Ast_async.dig_async_payload_from_function expr_ in
   let rec collect_params ~n_fun ~params expr =
     match expr with
     | {

tests/syntax_tests/data/parsing/grammar/expressions/expected/async.res.txt

@@ -35,15 +35,15 @@ let ex4 = (((foo.bar).baz)[@res.await ])
 let attr1 = ((fun [arity:1]x -> x + 1)[@res.async ][@a ])
 let attr2 = ((fun (type a) ->
   ((fun [arity:1]() -> fun (type b) -> fun (type c) -> fun [arity:1]x -> 3)
-  [@res.async ]))[@res.async ][@a ])
+  [@res.async ]))[@a ])
 let attr3 = ((fun (type a) ->
-  fun [arity:1]() -> ((fun (type b) -> fun (type c) -> ((fun [arity:1]x -> 3)
-    [@res.async ]))[@res.async ]))
+  fun [arity:1]() -> fun (type b) -> fun (type c) -> ((fun [arity:1]x -> 3)
+    [@res.async ]))
   [@a ])
 let attr4 = ((fun (type a) ->
   fun [arity:1]() -> ((fun (type b) -> fun (type c) -> ((fun [arity:1]x -> 3)
-    [@res.async ]))[@res.async ][@b ]))
+    [@res.async ]))[@b ]))
   [@a ])
 let (attr5 : int) = ((fun (type a) -> fun (type b) -> fun (type c) ->
-  ((fun [arity:1]() -> fun [arity:1](x : a) -> x)[@res.async ]))
-  [@res.async ][@a ][@b ])
+  ((fun [arity:1]() -> fun [arity:1](x : a) -> x)[@res.async ]))[@a ]
+  [@b ])