Support type instantiation during autocompletion.

CHANGELOG.md

@@ -21,6 +21,7 @@
 
 #### :bug: Bug Fix
 
+- Fix issue where autocomplete would not perform type instantiation https://github.com/rescript-lang/rescript-vscode/pull/561
 - Fix issue where hovering over a field in record construction would show the type without instantiating its type arguments https://github.com/rescript-lang/rescript-vscode/pull/560
 - Fix Incorrect semantic highlighting of `external` declarations https://github.com/rescript-lang/rescript-vscode/pull/517
 - Fix issue where doc comment with nested comments inside is not shown properly on hover https://github.com/rescript-lang/rescript-vscode/pull/526

analysis/src/CompletionBackEnd.ml

@@ -980,14 +980,75 @@ let findLocalCompletionsWithOpens ~pos ~(env : QueryEnv.t) ~prefix ~exact ~opens
     (* There's no local completion for fields *)
     []
 
+let instantiateType ~typeParams ~typeArgs (t : Types.type_expr) =
+  if typeParams = [] || typeArgs = [] then t
+  else
+    let rec applySub tp ta t =
+      match (tp, ta) with
+      | t1 :: tRest1, t2 :: tRest2 ->
+        if t1 = t then t2 else applySub tRest1 tRest2 t
+      | [], _ | _, [] -> assert false
+    in
+    let rec loop (t : Types.type_expr) =
+      match t.desc with
+      | Tlink t -> loop t
+      | Tvar _ -> applySub typeParams typeArgs t
+      | Tunivar _ -> t
+      | Tconstr (path, args, memo) ->
+        {t with desc = Tconstr (path, args |> List.map loop, memo)}
+      | Tsubst t -> loop t
+      | Tvariant rd -> {t with desc = Tvariant (rowDesc rd)}
+      | Tnil -> t
+      | Tarrow (lbl, t1, t2, c) ->
+        {t with desc = Tarrow (lbl, loop t1, loop t2, c)}
+      | Ttuple tl -> {t with desc = Ttuple (tl |> List.map loop)}
+      | Tobject (t, r) -> {t with desc = Tobject (loop t, r)}
+      | Tfield (n, k, t1, t2) -> {t with desc = Tfield (n, k, loop t1, loop t2)}
+      | Tpoly (t, []) -> loop t
+      | Tpoly (t, tl) -> {t with desc = Tpoly (loop t, tl |> List.map loop)}
+      | Tpackage (p, l, tl) ->
+        {t with desc = Tpackage (p, l, tl |> List.map loop)}
+    and rowDesc (rd : Types.row_desc) =
+      let row_fields =
+        rd.row_fields |> List.map (fun (l, rf) -> (l, rowField rf))
+      in
+      let row_more = loop rd.row_more in
+      let row_name =
+        match rd.row_name with
+        | None -> None
+        | Some (p, tl) -> Some (p, tl |> List.map loop)
+      in
+      {rd with row_fields; row_more; row_name}
+    and rowField (rf : Types.row_field) =
+      match rf with
+      | Rpresent None -> rf
+      | Rpresent (Some t) -> Rpresent (Some (loop t))
+      | Reither (b1, tl, b2, r) -> Reither (b1, tl |> List.map loop, b2, r)
+      | Rabsent -> Rabsent
+    in
+    loop t
+
 let rec extractRecordType ~env ~package (t : Types.type_expr) =
   match t.desc with
   | Tlink t1 | Tsubst t1 | Tpoly (t1, []) -> extractRecordType ~env ~package t1
-  | Tconstr (path, _, _) -> (
+  | Tconstr (path, typeArgs, _) -> (
     match References.digConstructor ~env ~package path with
     | Some (env, ({item = {kind = Record fields}} as typ)) ->
+      let typeParams = typ.item.decl.type_params in
+      let fields =
+        fields
+        |> List.map (fun field ->
+               let fieldTyp =
+                 field.typ |> instantiateType ~typeParams ~typeArgs
+               in
+               {field with typ = fieldTyp})
+      in
       Some (env, fields, typ)
-    | Some (env, {item = {decl = {type_manifest = Some t1}}}) ->
+    | Some
+        ( env,
+          {item = {decl = {type_manifest = Some t1; type_params = typeParams}}}
+        ) ->
+      let t1 = t1 |> instantiateType ~typeParams ~typeArgs in
       extractRecordType ~env ~package t1
     | _ -> None)
   | _ -> None
@@ -996,9 +1057,13 @@ let rec extractObjectType ~env ~package (t : Types.type_expr) =
   match t.desc with
   | Tlink t1 | Tsubst t1 | Tpoly (t1, []) -> extractObjectType ~env ~package t1
   | Tobject (tObj, _) -> Some (env, tObj)
-  | Tconstr (path, _, _) -> (
+  | Tconstr (path, typeArgs, _) -> (
     match References.digConstructor ~env ~package path with
-    | Some (env, {item = {decl = {type_manifest = Some t1}}}) ->
+    | Some
+        ( env,
+          {item = {decl = {type_manifest = Some t1; type_params = typeParams}}}
+        ) ->
+      let t1 = t1 |> instantiateType ~typeParams ~typeArgs in
       extractObjectType ~env ~package t1
     | _ -> None)
   | _ -> None
@@ -1008,9 +1073,14 @@ let extractFunctionType ~env ~package typ =
     match t.desc with
     | Tlink t1 | Tsubst t1 | Tpoly (t1, []) -> loop ~env acc t1
     | Tarrow (label, tArg, tRet, _) -> loop ~env ((label, tArg) :: acc) tRet
-    | Tconstr (path, _, _) -> (
+    | Tconstr (path, typeArgs, _) -> (
       match References.digConstructor ~env ~package path with
-      | Some (env, {item = {decl = {type_manifest = Some t1}}}) ->
+      | Some
+          ( env,
+            {
+              item = {decl = {type_manifest = Some t1; type_params = typeParams}};
+            } ) ->
+        let t1 = t1 |> instantiateType ~typeParams ~typeArgs in
         loop ~env acc t1
       | _ -> (List.rev acc, t))
     | _ -> (List.rev acc, t)
@@ -1234,17 +1304,17 @@ let rec getCompletionsForContextPath ~package ~opens ~rawOpens ~allFiles ~pos
           | _ :: rest -> List.rev rest
           | [] -> [])
       in
-      let getConstr typ =
+      let getConstrPath typ =
         match typ.Types.desc with
-        | Tconstr (path, _, _)
-        | Tlink {desc = Tconstr (path, _, _)}
-        | Tsubst {desc = Tconstr (path, _, _)}
-        | Tpoly ({desc = Tconstr (path, _, _)}, []) ->
+        | Tconstr (path, _typeArgs, _)
+        | Tlink {desc = Tconstr (path, _typeArgs, _)}
+        | Tsubst {desc = Tconstr (path, _typeArgs, _)}
+        | Tpoly ({desc = Tconstr (path, _typeArgs, _)}, []) ->
           Some path
         | _ -> None
       in
       let fromType typ =
-        match getConstr typ with
+        match getConstrPath typ with
         | None -> None
         | Some path -> Some (getModulePath path)
       in
@@ -1668,9 +1738,18 @@ Note: The `@react.component` decorator requires the react-jsx config to be set i
           | Tarrow ((Labelled l | Optional l), tArg, tRet, _) ->
             (l, tArg) :: getLabels ~env tRet
           | Tarrow (Nolabel, _, tRet, _) -> getLabels ~env tRet
-          | Tconstr (path, _, _) -> (
+          | Tconstr (path, typeArgs, _) -> (
             match References.digConstructor ~env ~package path with
-            | Some (env, {item = {decl = {type_manifest = Some t1}}}) ->
+            | Some
+                ( env,
+                  {
+                    item =
+                      {
+                        decl =
+                          {type_manifest = Some t1; type_params = typeParams};
+                      };
+                  } ) ->
+              let t1 = t1 |> instantiateType ~typeParams ~typeArgs in
               getLabels ~env t1
             | _ -> [])
           | _ -> []

analysis/tests/src/Hover.res

@@ -165,4 +165,22 @@ module TypeSubstitutionRecords = {
   //                   ^hov
   let x2: foobar = {content: {age: 42}, zzz: ""}
   //                  ^hov
+
+  // x1.content.
+  //            ^com
+
+  // x2.content.
+  //            ^com
+
+  type foo2<'b> = foo<'b>
+  type foobar2 = foo2<bar>
+
+  let y1: foo2<bar> = {content: {age: 42}, zzz: ""}
+  let y2: foobar2 = {content: {age: 42}, zzz: ""}
+
+  // y1.content.
+  //            ^com
+
+  // y2.content.
+  //            ^com
 }

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

@@ -110,3 +110,51 @@ Hover src/Hover.res 163:23
 Hover src/Hover.res 165:22
 {"contents": "```rescript\nfoobar\n```\n\n```rescript\ntype foobar = foo<bar>\n```"}
 
+Complete src/Hover.res 168:16
+posCursor:[168:16] posNoWhite:[168:15] Found expr:[168:5->168:16]
+Pexp_field [168:5->168:15] _:[174:2->168:16]
+Completable: Cpath Value[x1].content.""
+[{
+    "label": "age",
+    "kind": 5,
+    "tags": [],
+    "detail": "age: int\n\ntype bar = {age: int}",
+    "documentation": null
+  }]
+
+Complete src/Hover.res 171:16
+posCursor:[171:16] posNoWhite:[171:15] Found expr:[171:5->171:16]
+Pexp_field [171:5->171:15] _:[174:2->171:16]
+Completable: Cpath Value[x2].content.""
+[{
+    "label": "age",
+    "kind": 5,
+    "tags": [],
+    "detail": "age: int\n\ntype bar = {age: int}",
+    "documentation": null
+  }]
+
+Complete src/Hover.res 180:16
+posCursor:[180:16] posNoWhite:[180:15] Found expr:[180:5->180:16]
+Pexp_field [180:5->180:15] _:[185:0->180:16]
+Completable: Cpath Value[y1].content.""
+[{
+    "label": "age",
+    "kind": 5,
+    "tags": [],
+    "detail": "age: int\n\ntype bar = {age: int}",
+    "documentation": null
+  }]
+
+Complete src/Hover.res 183:16
+posCursor:[183:16] posNoWhite:[183:15] Found expr:[183:5->183:16]
+Pexp_field [183:5->183:15] _:[185:0->183:16]
+Completable: Cpath Value[y2].content.""
+[{
+    "label": "age",
+    "kind": 5,
+    "tags": [],
+    "detail": "age: int\n\ntype bar = {age: int}",
+    "documentation": null
+  }]
+