one step forward (and one backward) in resolving aliases in pipe completion

Author: zth

analysis/src/CompletionBackEnd.ml

@@ -723,6 +723,10 @@ let rec getCompletionsForContextPath ~full ~opens ~rawOpens ~allFiles ~pos ~env
       |> completionsGetTypeEnv
     with
     | Some (typ, envFromCompletionItem) -> (
+      let env, typ =
+        typ |> TypeUtils.resolveTypeForPipeCompletion ~env ~package
+      in
+
       (* 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

analysis/src/TypeUtils.ml

@@ -148,6 +148,19 @@ let rec extractType ~env ~package (t : Types.type_expr) =
     Some (Tpolyvariant {env; constructors; typeExpr = t})
   | _ -> None
 
+let rec resolveTypeForPipeCompletion ~env ~package (t : Types.type_expr) =
+  match t.desc with
+  | Tlink t1 | Tsubst t1 | Tpoly (t1, []) ->
+    resolveTypeForPipeCompletion ~env ~package t1
+  (* Don't descend into types named "t". Type t is a convention in the ReScript ecosystem. *)
+  | Tconstr (path, _, _) when path |> Path.last = "t" -> (env, t)
+  | Tconstr (path, _, _) -> (
+    match References.digConstructor ~env ~package path with
+    | Some (env, {item = {decl = {type_manifest = Some typ}}}) ->
+      resolveTypeForPipeCompletion ~env ~package typ
+    | _ -> (env, t))
+  | _ -> (env, t)
+
 (** This moves through a nested path via a set of instructions, trying to resolve the type at the end of the path. *)
 let rec resolveNested (typ : completionType) ~env ~package ~nested =
   match nested with

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

@@ -1745,17 +1745,5 @@ posCursor:[425:8] posNoWhite:[425:7] Found expr:[425:3->425:8]
 Completable: Cpath Value[ok]->g
 Raw opens: 2 Shadow.B.place holder ... Shadow.A.place holder
 Resolved opens 2 Completion.res Completion.res
-[{
-    "label": "Belt.Result.getExn",
-    "kind": 12,
-    "tags": [],
-    "detail": "t<'a, 'b> => 'a",
-    "documentation": {"kind": "markdown", "value": "\n  `getExn(res)`: when `res` is `Ok(n)`, returns `n` when `res` is `Error(m)`, raise an exception\n\n  ```res example\n  Belt.Result.getExn(Belt.Result.Ok(42)) == 42\n\n  Belt.Result.getExn(Belt.Result.Error(\"Invalid data\")) /* raises exception */\n  ```\n"}
-  }, {
-    "label": "Belt.Result.getWithDefault",
-    "kind": 12,
-    "tags": [],
-    "detail": "(t<'a, 'b>, 'a) => 'a",
-    "documentation": {"kind": "markdown", "value": "\n  `getWithDefault(res, defaultValue)`: If `res` is `Ok(n)`, returns `n`,\n  otherwise `default`\n\n  ```res example\n  Belt.Result.getWithDefault(Ok(42), 0) == 42\n\n  Belt.Result.getWithDefault(Error(\"Invalid Data\"), 0) == 0\n  ```\n"}
-  }]
+[]
 

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

@@ -259,7 +259,25 @@ Completable: Cpath Value[Belt, Array, reduce](Nolabel, Nolabel, Nolabel)->t
 Complete src/CompletionPipeChain.res 70:12
 posCursor:[70:12] posNoWhite:[70:11] Found expr:[70:3->0:-1]
 Completable: Cpath Value[aliased]->
-[]
+[{
+    "label": "CompletionSupport.Test.add",
+    "kind": 12,
+    "tags": [],
+    "detail": "t => int",
+    "documentation": null
+  }, {
+    "label": "CompletionSupport.Test.addSelf",
+    "kind": 12,
+    "tags": [],
+    "detail": "t => t",
+    "documentation": null
+  }, {
+    "label": "CompletionSupport.Test.make",
+    "kind": 12,
+    "tags": [],
+    "detail": "int => t",
+    "documentation": null
+  }]
 
 Complete src/CompletionPipeChain.res 73:15
 posCursor:[73:15] posNoWhite:[73:14] Found expr:[73:3->0:-1]