feat: Add Semantic modifier to parameter labels

Author: GrayJack

Sources/LanguageServerProtocol/SupportTypes/SemanticTokenModifiers.swift

@@ -47,6 +47,9 @@ public struct SemanticTokenModifiers: OptionSet, Hashable, Sendable {
   public static let fileScope = Self(rawValue: 1 << 19)
   public static let globalScope = Self(rawValue: 1 << 20)
 
+  // The following are our LSP extensions
+  public static let parameterLabel = Self(rawValue: 1 << 21)
+
   public var name: String? {
     switch self {
     case .declaration: return "declaration"
@@ -70,6 +73,7 @@ public struct SemanticTokenModifiers: OptionSet, Hashable, Sendable {
     case .classScope: return "classScope"
     case .fileScope: return "fileScope"
     case .globalScope: return "globalScope"
+    case .parameterLabel: return "parameterLabel"
     default: return nil
     }
   }
@@ -98,5 +102,6 @@ public struct SemanticTokenModifiers: OptionSet, Hashable, Sendable {
     .classScope,
     .fileScope,
     .globalScope,
+    .parameterLabel,
   ]
 }

Sources/SourceKitLSP/Swift/SemanticTokens.swift

@@ -150,7 +150,7 @@ extension SyntaxClassification {
     case .docLineComment, .docBlockComment:
       return (.comment, .documentation)
     case .argumentLabel:
-      return (.function, [])
+        return (.function, [.parameterLabel])
     }
   }
 }

Sources/SourceKitLSP/Swift/SyntaxHighlightingTokenParser.swift

@@ -164,7 +164,7 @@ struct SyntaxHighlightingTokenParser {
       // therefore we don't use .parameter here (which LSP clients like
       // VSCode seem to interpret as variable identifiers, however
       // causing a 'wrong highlighting' e.g. of `x` in `f(x y: Int) {}`)
-      return (.function, [.declaration])
+      return (.function, [.declaration, .parameterLabel])
     case values.refVarStatic,
       values.refVarClass,
       values.refVarInstance:

Tests/SourceKitLSPTests/SemanticTokensTests.swift

@@ -335,7 +335,7 @@ final class SemanticTokensTests: XCTestCase {
       expected: [
         TokenSpec(marker: "1️⃣", length: 4, kind: .keyword),
         TokenSpec(marker: "2️⃣", length: 1, kind: .identifier),
-        TokenSpec(marker: "3️⃣", length: 1, kind: .function),
+        TokenSpec(marker: "3️⃣", length: 1, kind: .function, modifiers: .parameterLabel),
         TokenSpec(marker: "4️⃣", length: 3, kind: .struct, modifiers: .defaultLibrary),
         TokenSpec(marker: "5️⃣", length: 1, kind: .identifier),
         TokenSpec(marker: "6️⃣", length: 6, kind: .struct, modifiers: .defaultLibrary),