support leveraging type annotations when inferring

Author: zth

Diff for: analysis/src/CompletionBackEnd.ml

@@ -588,6 +588,12 @@ let completionsGetTypeEnv = function
   | {Completion.kind = Field ({typ}, _); env} :: _ -> Some (typ, env)
   | _ -> None
 
+type getCompletionsForContextPathMode = Regular | Pipe
+
+type completionsTypeEnvTyp =
+  | TypeExpr of Types.type_expr
+  | ExtractedType of completionType
+
 let completionsGetCompletionType ~full = function
   | {Completion.kind = Value typ; env} :: _
   | {Completion.kind = ObjLabel typ; env} :: _
@@ -602,9 +608,27 @@ let completionsGetCompletionType ~full = function
   | {Completion.kind = ExtractedType (typ, _); env} :: _ -> Some (typ, env)
   | _ -> None
 
-type getCompletionsForContextPathMode = Regular | Pipe
+let rec completionsGetCompletionType2 ~full ~opens ~rawOpens ~allFiles ~pos
+    ~scope = function
+  | {Completion.kind = Value typ; env} :: _
+  | {Completion.kind = ObjLabel typ; env} :: _
+  | {Completion.kind = Field ({typ}, _); env} :: _ ->
+    Some (TypeExpr typ, env)
+  | {Completion.kind = FollowContextPath ctxPath; env} :: _ ->
+    ctxPath
+    |> getCompletionsForContextPath ~full ~env ~exact:true ~opens ~rawOpens
+         ~allFiles ~pos ~scope
+    |> completionsGetCompletionType2 ~full ~opens ~rawOpens ~allFiles ~pos
+         ~scope
+  | {Completion.kind = Type typ; env} :: _ -> (
+    match TypeUtils.extractTypeFromResolvedType typ ~env ~full with
+    | None -> None
+    | Some extractedType -> Some (ExtractedType extractedType, env))
+  | {Completion.kind = ExtractedType (typ, _); env} :: _ ->
+    Some (ExtractedType typ, env)
+  | _ -> None
 
-let rec completionsGetTypeEnv2 (completions : Completion.t list) ~full ~opens
+and completionsGetTypeEnv2 (completions : Completion.t list) ~full ~opens
     ~rawOpens ~allFiles ~pos ~scope =
   match completions with
   | {Completion.kind = Value typ; env} :: _ -> Some (typ, env)
@@ -744,29 +768,43 @@ and getCompletionsForContextPath ~full ~opens ~rawOpens ~allFiles ~pos ~env
     |> getCompletionsForPath ~package ~opens ~allFiles ~pos ~exact
          ~completionContext:Field ~env ~scope
   | CPField (cp, fieldName) -> (
-    match
+    let completionsForCtxPath =
       cp
       |> getCompletionsForContextPath ~full ~opens ~rawOpens ~allFiles ~pos ~env
            ~exact:true ~scope
-      |> completionsGetTypeEnv2 ~full ~opens ~rawOpens ~allFiles ~pos ~scope
-    with
-    | Some (typ, env) -> (
-      match typ |> TypeUtils.extractRecordType ~env ~package with
-      | Some (env, fields, typDecl) ->
-        fields
-        |> Utils.filterMap (fun field ->
-               if Utils.checkName field.fname.txt ~prefix:fieldName ~exact then
-                 Some
-                   (Completion.create field.fname.txt ~env
-                      ~docstring:field.docstring
-                      ~kind:
-                        (Completion.Field
-                           ( field,
-                             typDecl.item.decl
-                             |> Shared.declToString typDecl.name.txt )))
-               else None)
-      | None -> [])
-    | None -> [])
+    in
+    let extracted =
+      match
+        completionsForCtxPath
+        |> completionsGetCompletionType2 ~full ~opens ~rawOpens ~allFiles ~pos
+             ~scope
+      with
+      | Some (TypeExpr typ, env) -> (
+        match typ |> TypeUtils.extractRecordType ~env ~package with
+        | Some (env, fields, typDecl) ->
+          Some
+            ( env,
+              fields,
+              typDecl.item.decl |> Shared.declToString typDecl.name.txt )
+        | None -> None)
+      | Some (ExtractedType typ, env) -> (
+        match typ with
+        | Trecord {fields} ->
+          Some (env, fields, typ |> TypeUtils.extractedTypeToString)
+        | _ -> None)
+      | None -> None
+    in
+    match extracted with
+    | None -> []
+    | Some (env, fields, recordAsString) ->
+      fields
+      |> Utils.filterMap (fun field ->
+             if Utils.checkName field.fname.txt ~prefix:fieldName ~exact then
+               Some
+                 (Completion.create field.fname.txt ~env
+                    ~docstring:field.docstring
+                    ~kind:(Completion.Field (field, recordAsString)))
+             else None))
   | CPObj (cp, label) -> (
     match
       cp

Diff for: analysis/src/CompletionFrontEnd.ml

@@ -316,7 +316,8 @@ let completionWithParser1 ~currentFile ~debug ~offset ~path ~posCursor ~text =
       fields |> List.iter (fun (_, p) -> scopePattern ?contextPath p)
     | Ppat_array pl -> pl |> List.iter (scopePattern ?contextPath)
     | Ppat_or (p1, _) -> scopePattern ?contextPath p1
-    | Ppat_constraint (p, _) -> scopePattern ?contextPath p
+    | Ppat_constraint (p, coreType) ->
+      scopePattern ?contextPath:(TypeUtils.contextPathFromCoreType coreType) p
     | Ppat_type _ -> ()
     | Ppat_lazy p -> scopePattern ?contextPath p
     | Ppat_unpack {txt; loc} ->

Diff for: analysis/tests/src/CompletionInferValues.res

@@ -54,3 +54,6 @@ module Div = {
 
 // let _ = <div onMouseEnter={event => { let btn = event->JsxEvent.Mouse.button->Belt.Int.toString->Js.String2.split("/"); btn->ma }} />
 //                                                                                                                                ^com
+
+// let x: someRecord = {name: "Hello", age: 123}; x.
+//                                                  ^com

Diff for: analysis/tests/src/expected/CompletionInferValues.res.txt

@@ -202,3 +202,21 @@ Completable: Cpath Value[btn]->ma <<jsx>>
     "documentation": {"kind": "markdown", "value": "\nApplies the function (the second argument) to each item in the array, returning\na new array. The result array does not have to have elements of the same type\nas the input array. See\n[`Array.map`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map)\non MDN.\n\n```res example\nJs.Array2.map([12, 4, 8], x => x * x) == [144, 16, 64]\nJs.Array2.map([\"animal\", \"vegetable\", \"mineral\"], Js.String.length) == [6, 9, 7]\n```\n"}
   }]
 
+Complete src/CompletionInferValues.res 57:52
+posCursor:[57:52] posNoWhite:[57:51] Found expr:[57:50->57:52]
+Pexp_field [57:50->57:51] _:[60:0->57:52]
+Completable: Cpath Value[x].""
+[{
+    "label": "name",
+    "kind": 5,
+    "tags": [],
+    "detail": "name: string\n\ntype someRecord = {name: string, age: int}",
+    "documentation": null
+  }, {
+    "label": "age",
+    "kind": 5,
+    "tags": [],
+    "detail": "age: int\n\ntype someRecord = {name: string, age: int}",
+    "documentation": null
+  }]
+