Complete via TypeAtPos

CHANGELOG.md

@@ -17,6 +17,7 @@
 - Add support for syntax highlighting in `%raw` and `%ffi` extension points. https://github.com/rescript-lang/rescript-vscode/pull/774
 - Add completion to top level decorators. https://github.com/rescript-lang/rescript-vscode/pull/799
 - Add code action for wrapping patterns where option is expected with `Some`. https://github.com/rescript-lang/rescript-vscode/pull/806
+- Better completion from identifiers with inferred types. https://github.com/rescript-lang/rescript-vscode/pull/808
 
 #### :nail_care: Polish
 

analysis/src/CompletionBackEnd.ml

@@ -1113,6 +1113,14 @@ and getCompletionsForContextPath ~debug ~full ~opens ~rawOpens ~pos ~env ~exact
         [Completion.create "dummy" ~env ~kind:(kindFromInnerType typ)]
       | None -> [])
     | None -> [])
+  | CTypeAtPos loc -> (
+    match
+      References.getLocItem ~full ~pos:(Pos.ofLexing loc.loc_start) ~debug
+    with
+    | None -> []
+    | Some {locType = Typed (_, typExpr, _)} ->
+      [Completion.create "dummy" ~env ~kind:(Value typExpr)]
+    | _ -> [])
 
 let getOpens ~debug ~rawOpens ~package ~env =
   if debug && rawOpens <> [] then

analysis/src/CompletionFrontEnd.ml

@@ -591,6 +591,27 @@ let completionWithParser1 ~currentFile ~debug ~offset ~path ~posCursor ~text =
           (Completable.Cexpression
              {contextPath = ctxPath; prefix; nested = List.rev nested})
       | _ -> ())
+    | {pvb_pat = {ppat_desc = Ppat_var {loc}}; pvb_expr}
+      when locHasCursor pvb_expr.pexp_loc -> (
+      (* Expression without a type annotation. We can complete this if this
+         has compiled previously and there's a type available for the identifier itself.
+         This is nice because the type is assigned even if the assignment isn't complete.
+
+         E.g: let x = {name: "name", <com>}, when `x` has compiled. *)
+      match
+        pvb_expr
+        |> CompletionExpressions.traverseExpr ~exprPath:[] ~pos:posBeforeCursor
+             ~firstCharBeforeCursorNoWhite
+      with
+      | Some (prefix, nested) ->
+        (* This completion should be low prio, so let any deeper completion
+           hit first, and only set this TypeAtPos completion if nothing else
+           here hit. *)
+        Ast_iterator.default_iterator.value_binding iterator value_binding;
+        setResult
+          (Completable.Cexpression
+             {contextPath = CTypeAtPos loc; prefix; nested = List.rev nested})
+      | _ -> ())
     | {
      pvb_pat = {ppat_desc = Ppat_constraint (_pat, coreType); ppat_loc};
      pvb_expr;

analysis/src/SharedTypes.ml

@@ -592,6 +592,8 @@ module Completable = struct
       }
     | CJsxPropValue of {pathToComponent: string list; propName: string}
     | CPatternPath of {rootCtxPath: contextPath; nested: nestedPath list}
+    | CTypeAtPos of Location.t
+        (** A position holding something that might have a *compiled* type. *)
 
   type patternMode = Default | Destructuring
 
@@ -671,6 +673,7 @@ module Completable = struct
       ^ (nested
         |> List.map (fun nestedPath -> nestedPathToString nestedPath)
         |> String.concat "->")
+    | CTypeAtPos _loc -> "CTypeAtPos()"
 
   let toString = function
     | Cpath cp -> "Cpath " ^ contextPathToString cp

analysis/tests/src/TypeAtPosCompletion.res

@@ -0,0 +1,25 @@
+type optRecord = {
+  name: string,
+  age?: int,
+  online?: bool,
+}
+
+let optRecord = {
+  name: "Hello",
+  //             ^com
+}
+
+type someVariant = One(int, optRecord)
+
+let x = One(
+  1,
+  {
+    name: "What",
+    //            ^com
+  },
+)
+
+let arr = [
+  optRecord,
+  //        ^com
+]

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

@@ -1764,6 +1764,12 @@ Path T
     "tags": [],
     "detail": "file module",
     "documentation": null
+  }, {
+    "label": "TypeAtPosCompletion",
+    "kind": 9,
+    "tags": [],
+    "detail": "file module",
+    "documentation": null
   }, {
     "label": "TypeDefinition",
     "kind": 9,

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

@@ -68,6 +68,12 @@ Path CompletionSupport.TestComponent.make
     "tags": [],
     "detail": "file module",
     "documentation": null
+  }, {
+    "label": "TypeAtPosCompletion",
+    "kind": 9,
+    "tags": [],
+    "detail": "file module",
+    "documentation": null
   }, {
     "label": "TypeDefinition",
     "kind": 9,

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

@@ -12,5 +12,9 @@ posCursor:[9:56] posNoWhite:[9:55] Found expr:[9:13->9:66]
 JSX <SectionHeader:[9:13->9:26] > _children:9:26
 posCursor:[9:56] posNoWhite:[9:55] Found expr:__ghost__[9:10->9:67]
 Pexp_construct []:__ghost__[9:10->9:67] None
+Completable: Cexpression CTypeAtPos()=[]->variantPayload::::($1)
+Package opens Pervasives.JsxModules.place holder
+Resolved opens 1 pervasives
+ContextPath CTypeAtPos()
 null
 

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

@@ -0,0 +1,60 @@
+Complete src/TypeAtPosCompletion.res 7:17
+posCursor:[7:17] posNoWhite:[7:15] Found expr:[6:16->9:1]
+Completable: Cexpression CTypeAtPos()->recordBody
+Package opens Pervasives.JsxModules.place holder
+Resolved opens 1 pervasives
+ContextPath CTypeAtPos()
+[{
+    "label": "age",
+    "kind": 5,
+    "tags": [],
+    "detail": "age?: int\n\noptRecord",
+    "documentation": null
+  }, {
+    "label": "online",
+    "kind": 5,
+    "tags": [],
+    "detail": "online?: bool\n\noptRecord",
+    "documentation": null
+  }]
+
+Complete src/TypeAtPosCompletion.res 16:18
+posCursor:[16:18] posNoWhite:[16:16] Found expr:[13:8->19:1]
+Pexp_construct One:[13:8->13:11] [13:11->19:1]
+posCursor:[16:18] posNoWhite:[16:16] Found expr:[13:11->19:1]
+posCursor:[16:18] posNoWhite:[16:16] Found expr:[15:2->18:3]
+Completable: Cexpression CTypeAtPos()->variantPayload::One($1), recordBody
+Package opens Pervasives.JsxModules.place holder
+Resolved opens 1 pervasives
+ContextPath CTypeAtPos()
+[{
+    "label": "age",
+    "kind": 5,
+    "tags": [],
+    "detail": "age?: int\n\noptRecord",
+    "documentation": null
+  }, {
+    "label": "online",
+    "kind": 5,
+    "tags": [],
+    "detail": "online?: bool\n\noptRecord",
+    "documentation": null
+  }]
+
+Complete src/TypeAtPosCompletion.res 22:12
+posCursor:[22:12] posNoWhite:[22:11] Found expr:[21:10->24:1]
+Completable: Cexpression CTypeAtPos()->array
+Package opens Pervasives.JsxModules.place holder
+Resolved opens 1 pervasives
+ContextPath CTypeAtPos()
+[{
+    "label": "{}",
+    "kind": 12,
+    "tags": [],
+    "detail": "optRecord",
+    "documentation": null,
+    "sortText": "A",
+    "insertText": "{$0}",
+    "insertTextFormat": 2
+  }]
+