Expand type aliases when hovering (#881)

* expand type aliases when hovering

* changelog

Author: zth

CHANGELOG.md

@@ -14,6 +14,8 @@
 
 ## 1.32.0
 
+- Expand type aliases in hovers. https://github.com/rescript-lang/rescript-vscode/pull/881
+
 #### :bug: Bug Fix
 
 - Fix so that you don't need a leading `#` to complete for polyvariant constructors. https://github.com/rescript-lang/rescript-vscode/pull/874

analysis/src/Hover.ml

@@ -100,27 +100,27 @@ let findRelevantTypesFromType ~file ~package typ =
   let constructors = Shared.findTypeConstructors typesToSearch in
   constructors |> List.filter_map (fromConstructorPath ~env:envToSearch)
 
+let expandTypes ~file ~package ~supportsMarkdownLinks typ =
+  findRelevantTypesFromType typ ~file ~package
+  |> List.map (fun {decl; env; loc; path} ->
+         let linkToTypeDefinitionStr =
+           if supportsMarkdownLinks then
+             Markdown.goToDefinitionText ~env ~pos:loc.Warnings.loc_start
+           else ""
+         in
+         Markdown.divider
+         ^ (if supportsMarkdownLinks then Markdown.spacing else "")
+         ^ Markdown.codeBlock
+             (decl
+             |> Shared.declToString ~printNameAsIs:true
+                  (SharedTypes.pathIdentToString path))
+         ^ linkToTypeDefinitionStr ^ "\n")
+
 (* Produces a hover with relevant types expanded in the main type being hovered. *)
 let hoverWithExpandedTypes ~file ~package ~supportsMarkdownLinks typ =
   let typeString = Markdown.codeBlock (typ |> Shared.typeToString) in
-  let types = findRelevantTypesFromType typ ~file ~package in
-  let typeDefinitions =
-    types
-    |> List.map (fun {decl; env; loc; path} ->
-           let linkToTypeDefinitionStr =
-             if supportsMarkdownLinks then
-               Markdown.goToDefinitionText ~env ~pos:loc.Warnings.loc_start
-             else ""
-           in
-           Markdown.divider
-           ^ (if supportsMarkdownLinks then Markdown.spacing else "")
-           ^ Markdown.codeBlock
-               (decl
-               |> Shared.declToString ~printNameAsIs:true
-                    (SharedTypes.pathIdentToString path))
-           ^ linkToTypeDefinitionStr ^ "\n")
-  in
-  typeString :: typeDefinitions |> String.concat "\n"
+  typeString :: expandTypes ~file ~package ~supportsMarkdownLinks typ
+  |> String.concat "\n"
 
 (* Leverages autocomplete functionality to produce a hover for a position. This
    makes it (most often) work with unsaved content. *)
@@ -166,9 +166,14 @@ let getHoverViaCompletions ~debug ~path ~pos ~currentFile ~forHover
 
 let newHover ~full:{file; package} ~supportsMarkdownLinks locItem =
   match locItem.locType with
-  | TypeDefinition (name, decl, _stamp) ->
-    let typeDef = Shared.declToString name decl in
-    Some (Markdown.codeBlock typeDef)
+  | TypeDefinition (name, decl, _stamp) -> (
+    let typeDef = Markdown.codeBlock (Shared.declToString name decl) in
+    match decl.type_manifest with
+    | None -> Some typeDef
+    | Some typ ->
+      Some
+        (typeDef :: expandTypes ~file ~package ~supportsMarkdownLinks typ
+        |> String.concat "\n"))
   | LModule (Definition (stamp, _tip)) | LModule (LocalReference (stamp, _tip))
     -> (
     match Stamps.findModule file.stamps stamp with

analysis/tests/src/Hover.res

@@ -262,4 +262,7 @@ let coolVariant = CoolVariant
 //                               ^hov
 
 module Arr = Belt.Array
-//      ^hov
+//      ^hov
+
+type aliased = variant
+//    ^hov

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

@@ -264,3 +264,6 @@ Path x
 Hover src/Hover.res 263:8
 {"contents": {"kind": "markdown", "value": "\n [`Belt.Array`]()\n\n  **mutable array**: Utilities functions\n\n```rescript\nmodule Array: {\n  module Id\n  module Array\n  module SortArray\n  module MutableQueue\n  module MutableStack\n  module List\n  module Range\n  module Set\n  module Map\n  module MutableSet\n  module MutableMap\n  module HashSet\n  module HashMap\n  module Option\n  module Result\n  module Int\n  module Float\n}\n```"}}
 
+Hover src/Hover.res 266:6
+{"contents": {"kind": "markdown", "value": "```rescript\ntype aliased = variant\n```\n\n---\n\n```\n \n```\n```rescript\ntype variant = CoolVariant | OtherCoolVariant\n```\nGo to: [Type definition](command:rescript-vscode.go_to_location?%5B%22Hover.res%22%2C251%2C0%5D)\n"}}
+