Merge pull request swiftlang#39720 from DougGregor/pick-fix-task-instance-isCancelled

Author: DougGregor

stdlib/public/Concurrency/CMakeLists.txt

@@ -41,13 +41,10 @@ endif()
 # Don't emit extended frame info on platforms other than darwin, system
 # backtracer and system debugger are unlikely to support it.
 if(CMAKE_SYSTEM_NAME STREQUAL Darwin)
-  list(APPEND SWIFT_RUNTIME_CONCURRENCY_C_FLAGS
-    "-fswift-async-fp=${swift_concurrency_async_fp_mode}")
   list(APPEND SWIFT_RUNTIME_CONCURRENCY_SWIFT_FLAGS
     "-Xfrontend"
     "-swift-async-frame-pointer=${swift_concurrency_async_fp_mode}")
 else()
-  list(APPEND SWIFT_RUNTIME_CONCURRENCY_C_FLAGS "-fswift-async-fp=never")
 endif()
 
 add_swift_target_library(swift_Concurrency ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} IS_STDLIB

stdlib/public/Concurrency/Task.swift

@@ -860,6 +860,7 @@ func _taskCancel(_ task: Builtin.NativeObject)
 
 @available(SwiftStdlib 5.5, *)
 @_silgen_name("swift_task_isCancelled")
+@usableFromInline
 func _taskIsCancelled(_ task: Builtin.NativeObject) -> Bool
 
 @available(SwiftStdlib 5.5, *)

stdlib/public/Concurrency/TaskCancellation.swift

@@ -50,14 +50,8 @@ extension Task {
   /// There is no way to uncancel a task.
   ///
   /// - SeeAlso: `checkCancellation()`
-  public var isCancelled: Bool {
-    withUnsafeCurrentTask { task in
-      guard let task = task else {
-        return false
-      }
-
-      return _taskIsCancelled(task._task)
-    }
+  @_transparent public var isCancelled: Bool {
+    _taskIsCancelled(_task)
   }
 }
 

test/Concurrency/Runtime/async_task_handle_cancellation.swift

@@ -17,17 +17,22 @@
 @available(SwiftStdlib 5.5, *)
 @main struct Main {
   static func main() async {
-    let handle = detach {
+    let task = Task.detached {
       while (!Task.isCancelled) { // no need for await here, yay
         print("waiting")
       }
 
-      print("done")
+      print("inside: Task.isCancelled = \(Task.isCancelled)")
     }
 
-    handle.cancel()
+    task.cancel()
 
-    // CHECK: done
-    await handle.get()
+    await task.value
+    print("outside: task.isCancelled = \(task.isCancelled)")
+    print("outside: Task.isCancelled = \(Task.isCancelled)")
+
+    // CHECK-DAG: inside: Task.isCancelled = true
+    // CHECK-DAG: outside: task.isCancelled = true
+    // CHECK-DAG: outside: Task.isCancelled = false
   }
 }