Fix semantic highlighting for array spreads, array access and dict literals (#7789)

* Don't emit tokens for Belt.Array.concatMany generated by array spread

* Don't emit tokens for Primitive_dict.make generated by dict literal syntax

* Don't emit tokens for Array.get generated by array access syntax

* Output semantic tokens for direct usage of Belt.Array.concatMany

* Don't emit tokens for Array.set generated by array mutation syntax

* Add CHANGELOG entry

Author: mediremi

CHANGELOG.md

@@ -44,6 +44,7 @@
 
 #### :bug: Bug fix
 
+- Fix semantic highlighting for array spreads, array access and dict literals. https://github.com/rescript-lang/rescript/pull/7789
 - Preserve `@as(...)` decorator on record fields when creating interface. https://github.com/rescript-lang/rescript/pull/7779
 - Fix parse error with nested record types and attributes on the field name that has the nested record type. https://github.com/rescript-lang/rescript/pull/7781
 - Fix ppx resolution with package inside monorepo. https://github.com/rescript-lang/rescript/pull/7776

analysis/src/SemanticTokens.ml

@@ -247,12 +247,32 @@ let command ~debug ~emitter ~path =
     match e.pexp_desc with
     | Pexp_ident {txt = lid; loc} ->
       if lid <> Lident "not" then
-        if not loc.loc_ghost then
-          emitter
-          |> emitLongident ~pos:(Loc.start loc)
-               ~posEnd:(Some (Loc.end_ loc))
-               ~lid ~debug;
-      Ast_iterator.default_iterator.expr iterator e
+        if not loc.loc_ghost then (
+          (* Don't emit semantic tokens for identifiers not present in source code *)
+          let should_emit =
+            match lid with
+            (* Array spread (`...`) is converted to `Belt.Array.concatMany` with `@res.spread` decorator *)
+            | Ldot (Ldot (Lident "Belt", "Array"), "concatMany") ->
+              let has_spread_attr =
+                e.pexp_attributes
+                |> List.exists (fun ({Location.txt}, _) -> txt = "res.spread")
+              in
+              not has_spread_attr
+            (* Dict syntax (`dict{...}`) is converted to `Primitive_dict.make` *)
+            | Ldot (Lident "Primitive_dict", "make") -> false
+            | Lident "Primitive_dict" -> false
+            (* Array access (`arr[index]`) is converted to `Array.get` *)
+            | Ldot (Lident "Array", "get") -> false
+            (* Array mutation (`arr[index]`) is converted to `Array.set` *)
+            | Ldot (Lident "Array", "set") -> false
+            | _ -> true
+          in
+          if should_emit then
+            emitter
+            |> emitLongident ~pos:(Loc.start loc)
+                 ~posEnd:(Some (Loc.end_ loc))
+                 ~lid ~debug;
+          Ast_iterator.default_iterator.expr iterator e)
     | Pexp_jsx_element (Jsx_unary_element {jsx_unary_element_tag_name = lident})
       ->
       (*

tests/analysis_tests/tests/not_compiled/SemanticTokensArray.res

@@ -0,0 +1,3 @@
+let xs = [1, 2]
+let ys = [...xs, 3]
+//^sem

tests/analysis_tests/tests/not_compiled/SemanticTokensArrayAccess.res

@@ -0,0 +1,3 @@
+let x = xs[0]
+let x = xs[index]
+//^sem

tests/analysis_tests/tests/not_compiled/SemanticTokensArrayMutation.res

@@ -0,0 +1,2 @@
+xs[0] = 42
+//^sem

tests/analysis_tests/tests/not_compiled/SemanticTokensDict.res

@@ -0,0 +1,2 @@
+let d = dict{"foo": bar}
+//^sem

tests/analysis_tests/tests/not_compiled/expected/SemanticTokensArray.res.txt

@@ -0,0 +1 @@
+{"data":[0,4,2,1,0,1,4,2,1,0,0,9,2,1,0]}

tests/analysis_tests/tests/not_compiled/expected/SemanticTokensArrayAccess.res.txt

@@ -0,0 +1 @@
+{"data":[0,4,1,1,0,0,4,2,1,0,1,4,1,1,0,0,4,2,1,0,0,3,5,1,0]}

tests/analysis_tests/tests/not_compiled/expected/SemanticTokensArrayMutation.res.txt

@@ -0,0 +1 @@
+{"data":[0,0,2,1,0]}

tests/analysis_tests/tests/not_compiled/expected/SemanticTokensDict.res.txt

@@ -0,0 +1 @@
+{"data":[0,4,1,1,0,0,16,3,1,0]}