Pipe completion unknown/type parameter return types (#662)

Author: zth

analysis/src/Commands.ml

@@ -15,10 +15,10 @@ let getCompletions ~debug ~path ~pos ~currentFile ~forHover =
       (* Only perform expensive ast operations if there are completables *)
       match Cmt.loadFullCmtFromPath ~path with
       | None -> []
-      | Some {file; package} ->
-        let env = SharedTypes.QueryEnv.fromFile file in
+      | Some full ->
+        let env = SharedTypes.QueryEnv.fromFile full.file in
         completable
-        |> CompletionBackEnd.processCompletable ~debug ~package ~pos ~scope ~env
+        |> CompletionBackEnd.processCompletable ~debug ~full ~pos ~scope ~env
              ~forHover))
 
 let completion ~debug ~path ~pos ~currentFile =

analysis/src/CompletionBackEnd.ml

@@ -1157,8 +1157,17 @@ let completionsGetTypeEnv = function
   | {Completion.kind = Field ({typ}, _); env} :: _ -> Some (typ, env)
   | _ -> None
 
-let rec getCompletionsForContextPath ~package ~opens ~rawOpens ~allFiles ~pos
-    ~env ~exact ~scope (contextPath : Completable.contextPath) =
+let findReturnTypeOfFunctionAtLoc loc ~(env : QueryEnv.t) ~full ~debug =
+  match References.getLocItem ~full ~pos:(loc |> Loc.end_) ~debug with
+  | Some {locType = Typed (_, typExpr, _)} -> (
+    match extractFunctionType ~env ~package:full.package typExpr with
+    | args, tRet when args <> [] -> Some tRet
+    | _ -> None)
+  | _ -> None
+
+let rec getCompletionsForContextPath ~full ~opens ~rawOpens ~allFiles ~pos ~env
+    ~exact ~scope (contextPath : Completable.contextPath) =
+  let package = full.package in
   match contextPath with
   | CPString ->
     [
@@ -1181,8 +1190,8 @@ let rec getCompletionsForContextPath ~package ~opens ~rawOpens ~allFiles ~pos
   | CPApply (cp, labels) -> (
     match
       cp
-      |> getCompletionsForContextPath ~package ~opens ~rawOpens ~allFiles ~pos
-           ~env ~exact:true ~scope
+      |> getCompletionsForContextPath ~full ~opens ~rawOpens ~allFiles ~pos ~env
+           ~exact:true ~scope
       |> completionsGetTypeEnv
     with
     | Some (typ, env) -> (
@@ -1227,8 +1236,8 @@ let rec getCompletionsForContextPath ~package ~opens ~rawOpens ~allFiles ~pos
   | CPField (cp, fieldName) -> (
     match
       cp
-      |> getCompletionsForContextPath ~package ~opens ~rawOpens ~allFiles ~pos
-           ~env ~exact:true ~scope
+      |> getCompletionsForContextPath ~full ~opens ~rawOpens ~allFiles ~pos ~env
+           ~exact:true ~scope
       |> completionsGetTypeEnv
     with
     | Some (typ, env) -> (
@@ -1250,8 +1259,8 @@ let rec getCompletionsForContextPath ~package ~opens ~rawOpens ~allFiles ~pos
   | CPObj (cp, label) -> (
     match
       cp
-      |> getCompletionsForContextPath ~package ~opens ~rawOpens ~allFiles ~pos
-           ~env ~exact:true ~scope
+      |> getCompletionsForContextPath ~full ~opens ~rawOpens ~allFiles ~pos ~env
+           ~exact:true ~scope
       |> completionsGetTypeEnv
     with
     | Some (typ, env) -> (
@@ -1275,14 +1284,28 @@ let rec getCompletionsForContextPath ~package ~opens ~rawOpens ~allFiles ~pos
                else None)
       | None -> [])
     | None -> [])
-  | CPPipe (cp, funNamePrefix) -> (
+  | CPPipe {contextPath = cp; id = funNamePrefix; lhsLoc} -> (
     match
       cp
-      |> getCompletionsForContextPath ~package ~opens ~rawOpens ~allFiles ~pos
-           ~env ~exact:true ~scope
+      |> getCompletionsForContextPath ~full ~opens ~rawOpens ~allFiles ~pos ~env
+           ~exact:true ~scope
       |> completionsGetTypeEnv
     with
     | Some (typ, envFromCompletionItem) -> (
+      (* If the type we're completing on is a type parameter, we won't be able to do
+         completion unless we know what that type parameter is compiled as. This
+         attempts to look up the compiled type for that type parameter by looking
+         for compiled information at the loc of that expression. *)
+      let typ =
+        match typ with
+        | {Types.desc = Tvar _} -> (
+          match
+            findReturnTypeOfFunctionAtLoc lhsLoc ~env ~full ~debug:false
+          with
+          | None -> typ
+          | Some typFromLoc -> typFromLoc)
+        | _ -> typ
+      in
       let {
         arrayModulePath;
         optionModulePath;
@@ -1418,8 +1441,9 @@ let getOpens ~debug ~rawOpens ~package ~env =
   (* Last open takes priority *)
   List.rev resolvedOpens
 
-let processCompletable ~debug ~package ~scope ~env ~pos ~forHover
+let processCompletable ~debug ~full ~scope ~env ~pos ~forHover
     (completable : Completable.t) =
+  let package = full.package in
   let rawOpens = Scope.getRawOpens scope in
   let opens = getOpens ~debug ~rawOpens ~package ~env in
   let allFiles = FileSet.union package.projectFiles package.dependenciesFiles in
@@ -1433,8 +1457,8 @@ let processCompletable ~debug ~package ~scope ~env ~pos ~forHover
   | Cnone -> []
   | Cpath contextPath ->
     contextPath
-    |> getCompletionsForContextPath ~package ~opens ~rawOpens ~allFiles ~pos
-         ~env ~exact:forHover ~scope
+    |> getCompletionsForContextPath ~full ~opens ~rawOpens ~allFiles ~pos ~env
+         ~exact:forHover ~scope
   | Cjsx ([id], prefix, identsSeen) when String.uncapitalize_ascii id = id ->
     let mkLabel (name, typString) =
       Completion.create ~name ~kind:(Label typString) ~env
@@ -1783,7 +1807,7 @@ Note: The `@react.component` decorator requires the react-jsx config to be set i
     let labels =
       match
         cp
-        |> getCompletionsForContextPath ~package ~opens ~rawOpens ~allFiles ~pos
+        |> getCompletionsForContextPath ~full ~opens ~rawOpens ~allFiles ~pos
              ~env ~exact:true ~scope
         |> completionsGetTypeEnv
       with

analysis/src/CompletionFrontEnd.ml

@@ -180,6 +180,7 @@ let completePipeChain ~(lhs : Parsetree.expression) =
         pexp_loc;
         pexp_attributes;
       }
+    |> Option.map (fun ctxPath -> (ctxPath, d.pexp_loc))
     (* When the left side of the pipe we're completing is an identifier application.
        Example: someArray->filterAllTheGoodStuff-> *)
   | Pexp_apply
@@ -195,6 +196,7 @@ let completePipeChain ~(lhs : Parsetree.expression) =
         pexp_loc;
         pexp_attributes;
       }
+    |> Option.map (fun ctxPath -> (ctxPath, pexp_loc))
   | _ -> None
 
 let completionWithParser1 ~currentFile ~debug ~offset ~path ~posCursor ~text =
@@ -436,11 +438,12 @@ let completionWithParser1 ~currentFile ~debug ~offset ~path ~posCursor ~text =
       | None -> (
         match exprToContextPath lhs with
         | Some pipe ->
-          setResult (Cpath (CPPipe (pipe, id)));
+          setResult
+            (Cpath (CPPipe {contextPath = pipe; id; lhsLoc = lhs.pexp_loc}));
           true
         | None -> false)
-      | Some pipe ->
-        setResult (Cpath (CPPipe (pipe, id)));
+      | Some (pipe, lhsLoc) ->
+        setResult (Cpath (CPPipe {contextPath = pipe; id; lhsLoc}));
         true
     in
     match expr.pexp_desc with

analysis/src/Hover.ml

@@ -136,12 +136,13 @@ let getHoverViaCompletions ~debug ~path ~pos ~currentFile ~forHover
       (* Only perform expensive ast operations if there are completables *)
       match Cmt.loadFullCmtFromPath ~path with
       | None -> None
-      | Some {file; package} -> (
+      | Some full -> (
+        let {file; package} = full in
         let env = SharedTypes.QueryEnv.fromFile file in
         let completions =
           completable
-          |> CompletionBackEnd.processCompletable ~debug ~package ~pos ~scope
-               ~env ~forHover
+          |> CompletionBackEnd.processCompletable ~debug ~full ~pos ~scope ~env
+               ~forHover
         in
         match completions with
         | {kind = Label typString; docstring} :: _ ->

analysis/src/SharedTypes.ml

@@ -479,7 +479,12 @@ module Completable = struct
     | CPId of string list * completionContext
     | CPField of contextPath * string
     | CPObj of contextPath * string
-    | CPPipe of contextPath * string
+    | CPPipe of {
+        contextPath: contextPath;
+        id: string;
+        lhsLoc: Location.t;
+            (** The loc item for the left hand side of the pipe. *)
+      }
 
   type t =
     | Cdecorator of string  (** e.g. @module *)
@@ -513,7 +518,7 @@ module Completable = struct
         completionContextToString completionContext ^ list sl
       | CPField (cp, s) -> contextPathToString cp ^ "." ^ str s
       | CPObj (cp, s) -> contextPathToString cp ^ "[\"" ^ s ^ "\"]"
-      | CPPipe (cp, s) -> contextPathToString cp ^ "->" ^ s
+      | CPPipe {contextPath; id} -> contextPathToString contextPath ^ "->" ^ id
     in
     function
     | Cpath cp -> "Cpath " ^ contextPathToString cp

analysis/src/SignatureHelp.ml

@@ -18,12 +18,13 @@ let findFunctionType ~currentFile ~debug ~path ~pos =
       | Some (completable, scope) -> (
         match Cmt.loadFullCmtFromPath ~path with
         | None -> None
-        | Some {file; package} ->
+        | Some full ->
+          let {file; package} = full in
           let env = QueryEnv.fromFile file in
           Some
             ( completable
-              |> CompletionBackEnd.processCompletable ~debug ~package ~pos
-                   ~scope ~env ~forHover:true,
+              |> CompletionBackEnd.processCompletable ~debug ~full ~pos ~scope
+                   ~env ~forHover:true,
               env,
               package,
               file )))

analysis/tests/src/CompletionPipeChain.res

@@ -58,3 +58,7 @@ let f = int->Integer.increment(2)
 let _ = [123]->Js.Array2.forEach(v => Js.log(v))
 // ->
 //   ^com
+
+let _ = [123]->Belt.Array.reduce(0, (acc, curr) => acc + curr)
+// ->t
+//    ^com

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

@@ -239,3 +239,20 @@ posCursor:[58:5] posNoWhite:[58:4] Found expr:[57:8->0:-1]
 Completable: Cpath Value[Js, Array2, forEach](Nolabel, Nolabel)->
 []
 
+Complete src/CompletionPipeChain.res 62:6
+posCursor:[62:6] posNoWhite:[62:5] Found expr:[61:8->62:6]
+Completable: Cpath Value[Belt, Array, reduce](Nolabel, Nolabel, Nolabel)->t
+[{
+    "label": "Belt.Int.toString",
+    "kind": 12,
+    "tags": [],
+    "detail": "int => string",
+    "documentation": {"kind": "markdown", "value": "\n  Converts a given `int` to a `string`. Uses the JavaScript `String` constructor under the hood.\n\n  ```res example\n  Js.log(Belt.Int.toString(1) === \"1\") /* true */\n  ```\n"}
+  }, {
+    "label": "Belt.Int.toFloat",
+    "kind": 12,
+    "tags": [],
+    "detail": "int => float",
+    "documentation": {"kind": "markdown", "value": "\n  Converts a given `int` to a `float`.\n\n  ```res example\n  Js.log(Belt.Int.toFloat(1) === 1.0) /* true */\n  ```\n"}
+  }]
+