Support package access in NoAccessLevelOnExtensionDeclaration.

Author: allevato

Sources/SwiftFormat/Core/ModifierListSyntax+Convenience.swift

@@ -17,7 +17,8 @@ extension DeclModifierListSyntax {
   var accessLevelModifier: DeclModifierSyntax? {
     for modifier in self {
       switch modifier.name.tokenKind {
-      case .keyword(.public), .keyword(.private), .keyword(.fileprivate), .keyword(.internal):
+      case .keyword(.public), .keyword(.private), .keyword(.fileprivate), .keyword(.internal),
+          .keyword(.package):
         return modifier
       default:
         continue

Sources/SwiftFormat/Rules/NoAccessLevelOnExtensionDeclaration.swift

@@ -32,8 +32,8 @@ public final class NoAccessLevelOnExtensionDeclaration: SyntaxFormatRule {
     var result = node
 
     switch keyword {
-    // Public, private, or fileprivate keywords need to be moved to members
-    case .public, .private, .fileprivate:
+    // Public, private, fileprivate, or package keywords need to be moved to members
+    case .public, .private, .fileprivate, .package:
       // The effective access level of the members of a `private` extension is `fileprivate`, so
       // we have to update the keyword to ensure that the result is correct.
       var accessKeywordToAdd = accessKeyword

Tests/SwiftFormatTests/Rules/NoAccessLevelOnExtensionDeclarationTests.swift

@@ -128,6 +128,31 @@ final class NoAccessLevelOnExtensionDeclarationTests: LintOrFormatRuleTestCase {
     )
   }
 
+  func testPackageAccessLevel() {
+    assertFormatting(
+      NoAccessLevelOnExtensionDeclaration.self,
+      input: """
+        1️⃣package extension Foo {
+          2️⃣func f() {}
+        }
+        """,
+      expected: """
+        extension Foo {
+          package func f() {}
+        }
+        """,
+      findings: [
+        FindingSpec(
+          "1️⃣",
+          message: "move this 'package' access modifier to precede each member inside this extension",
+          notes: [
+            NoteSpec("2️⃣", message: "add 'package' access modifier to this declaration"),
+          ]
+        ),
+      ]
+    )
+  }
+
   func testPrivateIsEffectivelyFileprivate() {
     assertFormatting(
       NoAccessLevelOnExtensionDeclaration.self,