[TaskLocal] Carry access control modifiers into synthesized property

lib/Macros/Sources/SwiftMacros/CMakeLists.txt

@@ -14,6 +14,7 @@ add_swift_macro_library(SwiftMacros
   OptionSetMacro.swift
   DebugDescriptionMacro.swift
   DistributedResolvableMacro.swift
+  SyntaxExtensions.swift
   TaskLocalMacro.swift
   SWIFT_DEPENDENCIES
     SwiftDiagnostics

lib/Macros/Sources/SwiftMacros/DistributedResolvableMacro.swift

@@ -45,7 +45,7 @@ extension DistributedResolvableMacro {
       return []
     }
 
-    let accessModifiers: String = proto.accessModifiersString
+    let accessModifiers = proto.accessControlModifiers
 
     let requirementStubs =
       proto.memberBlock.members // requirements
@@ -71,7 +71,7 @@ extension DistributedResolvableMacro {
     return [extensionDecl.cast(ExtensionDeclSyntax.self)]
   }
 
-  static func stubMethodDecl(access: String, _ requirement: MemberBlockItemListSyntax.Element) -> String {
+  static func stubMethodDecl(access: DeclModifierListSyntax, _ requirement: MemberBlockItemListSyntax.Element) -> String {
     // do we need to stub a computed variable?
     if let variable = requirement.decl.as(VariableDeclSyntax.self) {
       var accessorStubs: [String] = []
@@ -142,7 +142,7 @@ extension DistributedResolvableMacro {
                  """, id: .invalidApplication)
     }
 
-    let accessModifiers = proto.accessModifiersString
+    let accessModifiers = proto.accessControlModifiers
 
     for req in proto.genericWhereClause?.requirements ?? [] {
       switch req.requirement {
@@ -198,31 +198,16 @@ extension DistributedResolvableMacro {
     }
   }
 
-  private static func typealiasActorSystem(access: String, _ proto: ProtocolDeclSyntax, _ type: TypeSyntax) -> DeclSyntax {
-    "\(raw: access)typealias ActorSystem = \(type)"
+  private static func typealiasActorSystem(access: DeclModifierListSyntax,
+                                           _ proto: ProtocolDeclSyntax,
+                                           _ type: TypeSyntax) -> DeclSyntax {
+    "\(access)typealias ActorSystem = \(type)"
   }
 }
 
 // ===== -----------------------------------------------------------------------
 // MARK: Convenience Extensions
 
-extension ProtocolDeclSyntax {
-  var accessModifiersString: String {
-    let modifiers = modifiers.filter { modifier in
-        modifier.isAccessControl
-      }
-
-    guard !modifiers.isEmpty else {
-      return ""
-    }
-
-    let string = modifiers
-      .map { "\($0.trimmed)" }
-      .joined(separator: " ")
-    return "\(string) "
-  }
-}
-
 extension TypeSyntax {
   fileprivate var isActorSystem: Bool {
     self.trimmedDescription == "ActorSystem"

lib/Macros/Sources/SwiftMacros/SyntaxExtensions.swift

@@ -0,0 +1,33 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2022-2024 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+// Common Syntax extensions used by standard library macros.                  //
+//===----------------------------------------------------------------------===//
+
+import SwiftSyntax
+import SwiftSyntaxMacros
+import SwiftDiagnostics
+
+extension DeclGroupSyntax {
+  internal var accessControlModifiers: DeclModifierListSyntax {
+      modifiers.filter { modifier in
+      modifier.isAccessControl
+    }
+  }
+}
+
+extension VariableDeclSyntax {
+  internal var accessControlModifiers: DeclModifierListSyntax {
+    modifiers.filter { modifier in
+      modifier.isAccessControl
+    }
+  }
+}

lib/Macros/Sources/SwiftMacros/TaskLocalMacro.swift

@@ -69,6 +69,9 @@ extension TaskLocalMacro: PeerMacro {
         message: "'@TaskLocal' property must have default value, or be optional", id: .mustBeVar)
     }
 
+    // Copy access modifiers
+    let access = varDecl.accessControlModifiers
+
     // If the property is global, do not prefix the synthesised decl with 'static'
     let isGlobal = context.lexicalContext.isEmpty
     let staticKeyword: TokenSyntax?
@@ -80,7 +83,7 @@ extension TaskLocalMacro: PeerMacro {
 
     return [
       """
-      \(staticKeyword)let $\(name)\(explicitTypeAnnotation) = TaskLocal(wrappedValue: \(initialValue))
+      \(access)\(staticKeyword)let $\(name)\(explicitTypeAnnotation) = TaskLocal(wrappedValue: \(initialValue))
       """
     ]
   }

test/Concurrency/Macros/task_local_macro_expansion.swift

@@ -0,0 +1,39 @@
+// REQUIRES: swift_swift_parser, asserts
+//
+// UNSUPPORTED: back_deploy_concurrency
+// REQUIRES: concurrency
+//
+// RUN: %empty-directory(%t)
+// RUN: %empty-directory(%t-scratch)
+
+// RUN: %target-swift-frontend -disable-availability-checking -typecheck -verify -plugin-path %swift-plugin-dir -I %t -dump-macro-expansions %s -dump-macro-expansions 2>&1 | %FileCheck %s
+
+struct Nein {
+  @TaskLocal
+  public static var example: String = "hello"
+}
+
+// CHECK: public static let $example: TaskLocal<String> = TaskLocal(wrappedValue: "hello")
+//
+// CHECK:  {
+// CHECK:    get {
+// CHECK:      $example.get()
+// CHECK:    }
+// CHECK:  }
+
+struct Available {
+  @available(OSX 10.9, *)
+  struct AvailableValue {}
+
+  @TaskLocal
+  @available(OSX 10.9, *)
+  private static var example: AvailableValue?
+}
+
+// CHECK: private static let $example: TaskLocal<AvailableValue?> = TaskLocal(wrappedValue: nil)
+//
+// CHECK:  {
+// CHECK:    get {
+// CHECK:      $example.get()
+// CHECK:    }
+// CHECK:  }

test/Concurrency/Runtime/async_task_locals_basic.swift

@@ -1,4 +1,4 @@
-// RUN: %target-run-simple-swift( -plugin-path %swift-plugin-dir -Xfrontend -disable-availability-checking -parse-as-library %import-libdispatch) | %FileCheck %s
+// RUN: %target-run-simple-swift( -plugin-path %swift-plugin-dir -parse-as-library %import-libdispatch) | %FileCheck %s
 
 // REQUIRES: executable_test
 // REQUIRES: concurrency
@@ -37,8 +37,16 @@ enum TL {
 }
 
 @TaskLocal
+@available(SwiftStdlib 5.1, *)
 var globalTaskLocal: StringLike = StringLike("<not-set>")
 
+@available(SwiftStdlib 5.10, *)
+struct LessAvailable {}
+
+@TaskLocal
+@available(SwiftStdlib 5.10, *)
+var globalLessAvailable: LessAvailable?
+
 @available(SwiftStdlib 5.1, *)
 final class ClassTaskLocal: Sendable {
   init() {