Make completion engine understand await

CHANGELOG.md

@@ -22,6 +22,7 @@
 #### :nail_care: Polish
 
 - Revamp "Insert missing cases" code action to make it apply in more cases and be much more robust. https://github.com/rescript-lang/rescript-vscode/pull/804
+- Make the completion engine understand async/await. https://github.com/rescript-lang/rescript-vscode/pull/813
 
 #### :bug: Bug Fix
 

analysis/src/CompletionBackEnd.ml

@@ -735,6 +735,16 @@ and getCompletionsForContextPath ~debug ~full ~opens ~rawOpens ~pos ~env ~exact
           ~kind:
             (Completion.ExtractedType (Toption (env, ExtractedType typ), `Type));
       ])
+  | CPAwait cp -> (
+    match
+      cp
+      |> getCompletionsForContextPath ~debug ~full ~opens ~rawOpens ~pos ~env
+           ~exact:true ~scope
+      |> completionsGetCompletionType ~full
+    with
+    | Some (Tpromise (env, typ), _env) ->
+      [Completion.create "dummy" ~env ~kind:(Completion.Value typ)]
+    | _ -> [])
   | CPId (path, completionContext) ->
     path
     |> getCompletionsForPath ~debug ~package ~opens ~full ~pos ~exact
@@ -1433,6 +1443,7 @@ let rec completeTypedValue ~full ~prefix ~completionContext ~mode
           ]
         ~env;
     ]
+  | Tpromise _ -> []
 
 let rec processCompletable ~debug ~full ~scope ~env ~pos ~forHover completable =
   if debug then

analysis/src/CompletionFrontEnd.ml

@@ -136,7 +136,7 @@ let findArgCompletables ~(args : arg list) ~endPos ~posBeforeCursor
          })
   | _ -> loop args
 
-let rec exprToContextPath (e : Parsetree.expression) =
+let rec exprToContextPathInner (e : Parsetree.expression) =
   match e.pexp_desc with
   | Pexp_constant (Pconst_string _) -> Some Completable.CPString
   | Pexp_constant (Pconst_integer _) -> Some CPInt
@@ -199,6 +199,15 @@ let rec exprToContextPath (e : Parsetree.expression) =
     else None
   | _ -> None
 
+and exprToContextPath (e : Parsetree.expression) =
+  match
+    ( Res_parsetree_viewer.hasAwaitAttribute e.pexp_attributes,
+      exprToContextPathInner e )
+  with
+  | true, Some ctxPath -> Some (CPAwait ctxPath)
+  | false, Some ctxPath -> Some ctxPath
+  | _, None -> None
+
 let completePipeChain (exp : Parsetree.expression) =
   (* Complete the end of pipe chains by reconstructing the pipe chain as a single pipe,
      so it can be completed.

analysis/src/SharedTypes.ml

@@ -310,6 +310,7 @@ type innerType = TypeExpr of Types.type_expr | ExtractedType of completionType
 and completionType =
   | Tuple of QueryEnv.t * Types.type_expr list * Types.type_expr
   | Texn of QueryEnv.t
+  | Tpromise of QueryEnv.t * Types.type_expr
   | Toption of QueryEnv.t * innerType
   | Tbool of QueryEnv.t
   | Tarray of QueryEnv.t * innerType
@@ -578,6 +579,7 @@ module Completable = struct
     | CPId of string list * completionContext
     | CPField of contextPath * string
     | CPObj of contextPath * string
+    | CPAwait of contextPath
     | CPPipe of {
         contextPath: contextPath;
         id: string;
@@ -631,6 +633,7 @@ module Completable = struct
     | CPInt -> "int"
     | CPFloat -> "float"
     | CPBool -> "bool"
+    | CPAwait ctxPath -> "await " ^ contextPathToString ctxPath
     | CPOption ctxPath -> "option<" ^ contextPathToString ctxPath ^ ">"
     | CPApply (cp, labels) ->
       contextPathToString cp ^ "("

analysis/src/TypeUtils.ml

@@ -115,6 +115,8 @@ let rec extractType ~env ~package (t : Types.type_expr) =
   | Tlink t1 | Tsubst t1 | Tpoly (t1, []) -> extractType ~env ~package t1
   | Tconstr (Path.Pident {name = "option"}, [payloadTypeExpr], _) ->
     Some (Toption (env, TypeExpr payloadTypeExpr))
+  | Tconstr (Path.Pident {name = "promise"}, [payloadTypeExpr], _) ->
+    Some (Tpromise (env, payloadTypeExpr))
   | Tconstr (Path.Pident {name = "array"}, [payloadTypeExpr], _) ->
     Some (Tarray (env, TypeExpr payloadTypeExpr))
   | Tconstr (Path.Pident {name = "bool"}, [], _) -> Some (Tbool env)
@@ -595,6 +597,7 @@ let rec extractedTypeToString ?(inner = false) = function
     "option<" ^ Shared.typeToString innerTyp ^ ">"
   | Toption (_, ExtractedType innerTyp) ->
     "option<" ^ extractedTypeToString ~inner:true innerTyp ^ ">"
+  | Tpromise (_, innerTyp) -> "promise<" ^ Shared.typeToString innerTyp ^ ">"
   | Tvariant {variantDecl; variantName} ->
     if inner then variantName else Shared.declToString variantName variantDecl
   | Trecord {definition = `NameOnly name; fields} ->

analysis/tests/src/CompletionPattern.res

@@ -206,3 +206,8 @@ let xn: exn = Obj.magic()
 
 // switch xn { | }
 //              ^com
+
+let getThing = async () => One
+
+// switch await getThing() { | }
+//                            ^com

analysis/tests/src/expected/CompletionPattern.res.txt

@@ -1070,3 +1070,38 @@ Path xn
     "documentation": {"kind": "markdown", "value": "Matches on a JavaScript error. Read more in the [documentation on catching JS exceptions](https://rescript-lang.org/docs/manual/latest/exception#catching-js-exceptions)."}
   }]
 
+Complete src/CompletionPattern.res 211:30
+XXX Not found!
+Completable: Cpattern await Value[getThing](Nolabel)
+Package opens Pervasives.JsxModules.place holder
+Resolved opens 1 pervasives
+ContextPath await Value[getThing](Nolabel)
+ContextPath Value[getThing](Nolabel)
+ContextPath Value[getThing]
+Path getThing
+[{
+    "label": "One",
+    "kind": 4,
+    "tags": [],
+    "detail": "One\n\ntype someVariant = One | Two(bool) | Three(someRecord, bool)",
+    "documentation": null,
+    "insertText": "One",
+    "insertTextFormat": 2
+  }, {
+    "label": "Two(_)",
+    "kind": 4,
+    "tags": [],
+    "detail": "Two(bool)\n\ntype someVariant = One | Two(bool) | Three(someRecord, bool)",
+    "documentation": null,
+    "insertText": "Two(${1:_})",
+    "insertTextFormat": 2
+  }, {
+    "label": "Three(_, _)",
+    "kind": 4,
+    "tags": [],
+    "detail": "Three(someRecord, bool)\n\ntype someVariant = One | Two(bool) | Three(someRecord, bool)",
+    "documentation": null,
+    "insertText": "Three(${1:_}, ${2:_})",
+    "insertTextFormat": 2
+  }]
+