Revert "[5.9 🍒] Add support for various new 5.9 features."

Sources/SwiftFormat/Core/ModifierListSyntax+Convenience.swift

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

Sources/SwiftFormat/PrettyPrint/TokenStreamCreator.swift

@@ -2293,7 +2293,6 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
 
   override func visit(_ node: GenericParameterSyntax) -> SyntaxVisitorContinueKind {
     before(node.firstToken(viewMode: .sourceAccurate), tokens: .open)
-    after(node.eachKeyword, tokens: .break)
     after(node.colon, tokens: .break)
     if let trailingComma = node.trailingComma {
       after(trailingComma, tokens: .close, .break(.same))
@@ -2313,28 +2312,6 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
     return .visitChildren
   }
 
-  override func visit(_ node: PackElementExprSyntax) -> SyntaxVisitorContinueKind {
-    // `each` cannot be separated from the following token, or it is parsed as an identifier itself.
-    after(node.eachKeyword, tokens: .space)
-    return .visitChildren
-  }
-
-  override func visit(_ node: PackElementTypeSyntax) -> SyntaxVisitorContinueKind {
-    // `each` cannot be separated from the following token, or it is parsed as an identifier itself.
-    after(node.eachKeyword, tokens: .space)
-    return .visitChildren
-  }
-
-  override func visit(_ node: PackExpansionExprSyntax) -> SyntaxVisitorContinueKind {
-    after(node.repeatKeyword, tokens: .break)
-    return .visitChildren
-  }
-
-  override func visit(_ node: PackExpansionTypeSyntax) -> SyntaxVisitorContinueKind {
-    after(node.repeatKeyword, tokens: .break)
-    return .visitChildren
-  }
-
   override func visit(_ node: ExpressionPatternSyntax) -> SyntaxVisitorContinueKind {
     return .visitChildren
   }
@@ -2504,27 +2481,6 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
     return .visitChildren
   }
 
-  override func visit(_ node: ConsumeExprSyntax) -> SyntaxVisitorContinueKind {
-    // The `consume` keyword cannot be separated from the following token or it will be parsed as
-    // an identifier.
-    after(node.consumeKeyword, tokens: .space)
-    return .visitChildren
-  }
-
-  override func visit(_ node: CopyExprSyntax) -> SyntaxVisitorContinueKind {
-    // The `copy` keyword cannot be separated from the following token or it will be parsed as an
-    // identifier.
-    after(node.copyKeyword, tokens: .space)
-    return .visitChildren
-  }
-
-  override func visit(_ node: DiscardStmtSyntax) -> SyntaxVisitorContinueKind {
-    // The `discard` keyword cannot be separated from the following token or it will be parsed as
-    // an identifier.
-    after(node.discardKeyword, tokens: .space)
-    return .visitChildren
-  }
-
   override func visit(_ node: InheritanceClauseSyntax) -> SyntaxVisitorContinueKind {
     // Normally, the open-break is placed before the open token. In this case, it's intentionally
     // ordered differently so that the inheritance list can start on the current line and only

Sources/SwiftFormat/Rules/AlwaysUseLiteralForEmptyCollectionInit.swift

@@ -166,7 +166,8 @@ public final class AlwaysUseLiteralForEmptyCollectionInit : SyntaxFormatRule {
   }
 
   private func getLiteralType(_ arrayLiteral: ArrayExprSyntax) -> TypeSyntax? {
-    guard arrayLiteral.elements.count == 1 else {
+    guard let elementExpr = arrayLiteral.elements.firstAndOnly,
+          elementExpr.is(ArrayElementSyntax.self) else {
       return nil
     }
 

Sources/SwiftFormat/Rules/NoAccessLevelOnExtensionDeclaration.swift

@@ -32,8 +32,8 @@ public final class NoAccessLevelOnExtensionDeclaration: SyntaxFormatRule {
     var result = node
 
     switch keyword {
-    // Public, private, fileprivate, or package keywords need to be moved to members
-    case .public, .private, .fileprivate, .package:
+    // Public, private, or fileprivate keywords need to be moved to members
+    case .public, .private, .fileprivate:
       // 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

@@ -128,31 +128,6 @@ 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,