follow variant payloads

Author: zth

analysis/src/TypeUtils.ml

@@ -358,6 +358,19 @@ let findTypeOfRecordField fields ~fieldName =
     let typ = if optional then Utils.unwrapIfOption typ else typ in
     Some typ
 
+let findTypeOfConstructorArg constructors ~constructorName ~payloadNum ~env =
+  match
+    constructors
+    |> List.find_opt (fun (c : Constructor.t) -> c.cname.txt = constructorName)
+  with
+  | Some {args = Args args} -> (
+    match List.nth_opt args payloadNum with
+    | None -> None
+    | Some (typ, _) -> Some (TypeExpr typ))
+  | Some {args = InlineRecord fields} when payloadNum = 0 ->
+    Some (ExtractedType (TinlineRecord {env; fields}))
+  | _ -> None
+
 let rec resolveNestedPatternPath (typ : innerType) ~env ~full ~nested =
   let t =
     match typ with
@@ -380,6 +393,14 @@ let rec resolveNestedPatternPath (typ : innerType) ~env ~full ~nested =
         match List.nth_opt tupleItems itemNum with
         | None -> None
         | Some typ -> Some (TypeExpr typ, env))
+      | NVariantPayload {constructorName; itemNum}, Tvariant {env; constructors}
+        -> (
+        match
+          constructors
+          |> findTypeOfConstructorArg ~constructorName ~payloadNum:itemNum ~env
+        with
+        | Some typ -> Some (typ, env)
+        | None -> None)
       | _ -> None))
   | patternPath :: nested -> (
     match t with
@@ -405,6 +426,14 @@ let rec resolveNestedPatternPath (typ : innerType) ~env ~full ~nested =
           |> Utils.Option.flatMap (fun typ ->
                  ExtractedType typ
                  |> resolveNestedPatternPath ~env ~full ~nested))
+      | NVariantPayload {constructorName; itemNum}, Tvariant {env; constructors}
+        -> (
+        match
+          constructors
+          |> findTypeOfConstructorArg ~constructorName ~payloadNum:itemNum ~env
+        with
+        | Some typ -> typ |> resolveNestedPatternPath ~env ~full ~nested
+        | None -> None)
       | _ -> None))
 
 let getArgs ~env (t : Types.type_expr) ~full =

analysis/tests/src/CompletionInferValues.res

@@ -99,6 +99,9 @@ type otherNestedRecord = {someRecord: someRecord, someTuple: (someVariant, int)}
 // let x: otherNestedRecord; switch x { | {someTuple} => let (_, someInt) = someTuple; someInt->toS }
 //                                                                                                 ^com
 
+// Follow variant payloads
+// let x: otherNestedRecord; switch x { | {someTuple:(Three(_, str), _)} => str->slic }
+//                                                                                   ^com
 let fnWithRecordCallback = (cb: someRecord => unit) => {
   let _ = cb
 }

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

@@ -222,7 +222,7 @@ Completable: Cpath Value[x].""
 
 Complete src/CompletionInferValues.res 74:78
 posCursor:[74:78] posNoWhite:[74:77] Found expr:[74:70->74:78]
-Pexp_field [74:70->74:77] _:[101:0->74:78]
+Pexp_field [74:70->74:77] _:[104:0->74:78]
 Completable: Cpath Value[srecord].""
 [{
     "label": "name",
@@ -240,7 +240,7 @@ Completable: Cpath Value[srecord].""
 
 Complete src/CompletionInferValues.res 78:86
 posCursor:[78:86] posNoWhite:[78:85] Found expr:[78:78->78:86]
-Pexp_field [78:78->78:85] _:[101:0->78:86]
+Pexp_field [78:78->78:85] _:[104:0->78:86]
 Completable: Cpath Value[aliased].""
 [{
     "label": "someRecord",
@@ -252,7 +252,7 @@ Completable: Cpath Value[aliased].""
 
 Complete src/CompletionInferValues.res 82:103
 posCursor:[82:103] posNoWhite:[82:102] Found expr:[82:92->82:103]
-Pexp_field [82:92->82:102] _:[101:0->82:103]
+Pexp_field [82:92->82:102] _:[104:0->82:103]
 Completable: Cpath Value[someRecord].""
 [{
     "label": "name",
@@ -319,12 +319,29 @@ Completable: Cpath Value[someInt]->toS
     "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"}
   }]
 
-Complete src/CompletionInferValues.res 105:26
-posCursor:[105:26] posNoWhite:[105:25] Found expr:[105:3->105:37]
-Pexp_apply ...[105:3->105:23] (...[105:24->105:36])
-posCursor:[105:26] posNoWhite:[105:25] Found expr:[105:24->105:36]
-posCursor:[105:26] posNoWhite:[105:25] Found pattern:[105:25->105:27]
-posCursor:[105:26] posNoWhite:[105:25] Found pattern:[105:25->105:27]
+Complete src/CompletionInferValues.res 102:85
+posCursor:[102:85] posNoWhite:[102:84] Found expr:[102:76->102:85]
+Completable: Cpath Value[str]->slic
+[{
+    "label": "Js.String2.sliceToEnd",
+    "kind": 12,
+    "tags": [],
+    "detail": "(t, ~from: int) => t",
+    "documentation": {"kind": "markdown", "value": "\n`sliceToEnd(str, from:n)` returns the substring of `str` starting at character\n`n` to the end of the string.\n- If `n` is negative, then it is evaluated as `length(str - n)`.\n- If `n` is greater than the length of `str`, then sliceToEnd returns the empty string.\n\nSee [`String.slice`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/slice) on MDN.\n\n```res example\nJs.String2.sliceToEnd(\"abcdefg\", ~from=4) == \"efg\"\nJs.String2.sliceToEnd(\"abcdefg\", ~from=-2) == \"fg\"\nJs.String2.sliceToEnd(\"abcdefg\", ~from=7) == \"\"\n```\n"}
+  }, {
+    "label": "Js.String2.slice",
+    "kind": 12,
+    "tags": [],
+    "detail": "(t, ~from: int, ~to_: int) => t",
+    "documentation": {"kind": "markdown", "value": "\n`slice(str, from:n1, to_:n2)` returns the substring of `str` starting at\ncharacter `n1` up to but not including `n2`.\n- If either `n1` or `n2` is negative, then it is evaluated as `length(str - n1)` or `length(str - n2)`.\n- If `n2` is greater than the length of `str`, then it is treated as `length(str)`.\n- If `n1` is greater than `n2`, slice returns the empty string.\n\nSee [`String.slice`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/slice) on MDN.\n\n```res example\nJs.String2.slice(\"abcdefg\", ~from=2, ~to_=5) == \"cde\"\nJs.String2.slice(\"abcdefg\", ~from=2, ~to_=9) == \"cdefg\"\nJs.String2.slice(\"abcdefg\", ~from=-4, ~to_=-2) == \"de\"\nJs.String2.slice(\"abcdefg\", ~from=5, ~to_=1) == \"\"\n```\n"}
+  }]
+
+Complete src/CompletionInferValues.res 109:26
+posCursor:[109:26] posNoWhite:[109:25] Found expr:[109:3->109:37]
+Pexp_apply ...[109:3->109:23] (...[109:24->109:36])
+posCursor:[109:26] posNoWhite:[109:25] Found expr:[109:24->109:36]
+posCursor:[109:26] posNoWhite:[109:25] Found pattern:[109:25->109:27]
+posCursor:[109:26] posNoWhite:[109:25] Found pattern:[109:25->109:27]
 Completable: Cpattern CArgument CArgument Value[fnWithRecordCallback]($0)($0)->recordBody
 [{
     "label": "name",