add _backDeploy and availability necessary for it

Author: ktoso

stdlib/public/BackDeployConcurrency/TaskLocal.swift

@@ -102,6 +102,7 @@ public final class TaskLocal<Value: Sendable>: Sendable, CustomStringConvertible
     self.defaultValue = defaultValue
   }
 
+  @usableFromInline
   var key: Builtin.RawPointer {
     unsafeBitCast(self, to: Builtin.RawPointer.self)
   }
@@ -135,7 +136,10 @@ public final class TaskLocal<Value: Sendable>: Sendable, CustomStringConvertible
   /// If the value is a reference type, it will be retained for the duration of
   /// the operation closure.
   @discardableResult
+  @inline(__always)
   @_unsafeInheritExecutor
+  @available(SwiftStdlib 5.1, *) // back deploy requires we declare the availability explicitly on this method
+  @_backDeploy(before: macOS 9999, iOS 9999, watchOS 9999, tvOS 9999) // SwiftStdlib 5.8 but it doesn't work with _backDeploy
   public func withValue<R>(_ valueDuringOperation: Value, operation: () async throws -> R,
                            file: String = #file, line: UInt = #line) async rethrows -> R {
     // check if we're not trying to bind a value from an illegal context; this may crash
@@ -161,6 +165,7 @@ public final class TaskLocal<Value: Sendable>: Sendable, CustomStringConvertible
   /// If the value is a reference type, it will be retained for the duration of
   /// the operation closure.
   @discardableResult
+  @inline(__always)
   public func withValue<R>(_ valueDuringOperation: Value, operation: () throws -> R,
                            file: String = #file, line: UInt = #line) rethrows -> R {
     // check if we're not trying to bind a value from an illegal context; this may crash
@@ -172,6 +177,7 @@ public final class TaskLocal<Value: Sendable>: Sendable, CustomStringConvertible
     return try operation()
   }
 
+  @inline(__always)
   public var projectedValue: TaskLocal<Value> {
     get {
       self
@@ -213,23 +219,27 @@ public final class TaskLocal<Value: Sendable>: Sendable, CustomStringConvertible
 // ==== ------------------------------------------------------------------------
 
 @available(SwiftStdlib 5.1, *)
+@usableFromInline
 @_silgen_name("swift_task_localValuePush")
 func _taskLocalValuePush<Value>(
   key: Builtin.RawPointer/*: Key*/,
   value: __owned Value
 ) // where Key: TaskLocal
 
 @available(SwiftStdlib 5.1, *)
+@usableFromInline
 @_silgen_name("swift_task_localValuePop")
 func _taskLocalValuePop()
 
 @available(SwiftStdlib 5.1, *)
+@usableFromInline
 @_silgen_name("swift_task_localValueGet")
 func _taskLocalValueGet(
   key: Builtin.RawPointer/*Key*/
 ) -> UnsafeMutableRawPointer? // where Key: TaskLocal
 
 @available(SwiftStdlib 5.1, *)
+@usableFromInline
 @_silgen_name("swift_task_localsCopyTo")
 func _taskLocalsCopy(
   to target: Builtin.NativeObject

stdlib/public/Concurrency/TaskLocal.swift

@@ -102,6 +102,7 @@ public final class TaskLocal<Value: Sendable>: Sendable, CustomStringConvertible
     self.defaultValue = defaultValue
   }
 
+  @usableFromInline
   var key: Builtin.RawPointer {
     unsafeBitCast(self, to: Builtin.RawPointer.self)
   }
@@ -136,6 +137,8 @@ public final class TaskLocal<Value: Sendable>: Sendable, CustomStringConvertible
   /// the operation closure.
   @discardableResult
   @_unsafeInheritExecutor
+  @available(SwiftStdlib 5.1, *) // back deploy requires we declare the availability explicitly on this method
+  @_backDeploy(before: macOS 9999, iOS 9999, watchOS 9999, tvOS 9999) // SwiftStdlib 5.8 but it doesn't work with _backDeploy
   public func withValue<R>(_ valueDuringOperation: Value, operation: () async throws -> R,
                            file: String = #fileID, line: UInt = #line) async rethrows -> R {
     // check if we're not trying to bind a value from an illegal context; this may crash
@@ -161,6 +164,7 @@ public final class TaskLocal<Value: Sendable>: Sendable, CustomStringConvertible
   /// If the value is a reference type, it will be retained for the duration of
   /// the operation closure.
   @discardableResult
+  @inline(__always)
   public func withValue<R>(_ valueDuringOperation: Value, operation: () throws -> R,
                            file: String = #fileID, line: UInt = #line) rethrows -> R {
     // check if we're not trying to bind a value from an illegal context; this may crash
@@ -172,6 +176,7 @@ public final class TaskLocal<Value: Sendable>: Sendable, CustomStringConvertible
     return try operation()
   }
 
+  @inline(__always)
   public var projectedValue: TaskLocal<Value> {
     get {
       self
@@ -213,23 +218,27 @@ public final class TaskLocal<Value: Sendable>: Sendable, CustomStringConvertible
 // ==== ------------------------------------------------------------------------
 
 @available(SwiftStdlib 5.1, *)
+@usableFromInline
 @_silgen_name("swift_task_localValuePush")
 func _taskLocalValuePush<Value>(
   key: Builtin.RawPointer/*: Key*/,
   value: __owned Value
 ) // where Key: TaskLocal
 
 @available(SwiftStdlib 5.1, *)
+@usableFromInline
 @_silgen_name("swift_task_localValuePop")
 func _taskLocalValuePop()
 
 @available(SwiftStdlib 5.1, *)
+@usableFromInline
 @_silgen_name("swift_task_localValueGet")
 func _taskLocalValueGet(
   key: Builtin.RawPointer/*Key*/
 ) -> UnsafeMutableRawPointer? // where Key: TaskLocal
 
 @available(SwiftStdlib 5.1, *)
+@usableFromInline
 @_silgen_name("swift_task_localsCopyTo")
 func _taskLocalsCopy(
   to target: Builtin.NativeObject