Merge pull request swiftlang#35071 from DougGregor/with-one-unsafe-continuation

[Concurrency] Remove extraneous copies of withUnsafe(Throwing)Continuation

Author: DougGregor

stdlib/public/Concurrency/PartialAsyncTask.swift

@@ -79,7 +79,9 @@ internal func _resumeUnsafeThrowingContinuationWithError<T>(
 
 #endif
 
-// Wrappers around unsafe continuation builtins
+/// The operation functions must resume the continuation *exactly once*.
+///
+/// The continuation will not begin executing until the operation function returns.
 @_alwaysEmitIntoClient
 public func withUnsafeContinuation<T>(
   _ fn: (UnsafeContinuation<T>) -> Void
@@ -89,6 +91,9 @@ public func withUnsafeContinuation<T>(
   }
 }
 
+/// The operation functions must resume the continuation *exactly once*.
+///
+/// The continuation will not begin executing until the operation function returns.
 @_alwaysEmitIntoClient
 public func withUnsafeThrowingContinuation<T>(
   _ fn: (UnsafeThrowingContinuation<T>) -> Void

stdlib/public/Concurrency/Task.swift

@@ -343,36 +343,6 @@ extension Task {
   }
 }
 
-// ==== UnsafeContinuation -----------------------------------------------------
-
-extension Task {
-  /// The operation functions must resume the continuation *exactly once*.
-  ///
-  /// The continuation will not begin executing until the operation function returns.
-  ///
-  /// ### Suspension
-  /// This function returns instantly and will never suspend.
-  /* @instantaneous */
-  public static func withUnsafeContinuation<T>(
-    operation: (UnsafeContinuation<T>) -> Void
-  ) async -> T {
-    fatalError("\(#function) not implemented yet.")
-  }
-
-  /// The operation functions must resume the continuation *exactly once*.
-  ///
-  /// The continuation will not begin executing until the operation function returns.
-  ///
-  /// ### Suspension
-  /// This function returns instantly and will never suspend.
-  /* @instantaneous */
-  public static func withUnsafeThrowingContinuation<T>(
-    operation: (UnsafeThrowingContinuation<T>) -> Void
-  ) async throws -> T {
-    fatalError("\(#function) not implemented yet.")
-  }
-}
-
 @_silgen_name("swift_task_getJobFlags")
 func getJobFlags(_ task: Builtin.NativeObject) -> Task.JobFlags
 

test/Concurrency/async_tasks.swift

@@ -26,7 +26,7 @@ func buyVegetables(
 
 // returns 1 or more vegetables or throws an error
 func buyVegetables(shoppingList: [String]) async throws -> [Vegetable] {
-  await try Task.withUnsafeThrowingContinuation { continuation in
+  await try withUnsafeThrowingContinuation { continuation in
     var veggies: [Vegetable] = []
 
     buyVegetables(
@@ -43,22 +43,22 @@ func buyVegetables(shoppingList: [String]) async throws -> [Vegetable] {
 func test_unsafeContinuations() async {
   // the closure should not allow async operations;
   // after all: if you have async code, just call it directly, without the unsafe continuation
-  let _: String = Task.withUnsafeContinuation { continuation in // expected-error{{invalid conversion from 'async' function of type '(UnsafeContinuation<String>) async -> Void' to synchronous function type '(UnsafeContinuation<String>) -> Void'}}
+  let _: String = withUnsafeContinuation { continuation in // expected-error{{invalid conversion from 'async' function of type '(UnsafeContinuation<String>) async -> Void' to synchronous function type '(UnsafeContinuation<String>) -> Void'}}
     let s = await someAsyncFunc() // rdar://70610141 for getting a better error message here
     continuation.resume(returning: s)
   }
 
-  let _: String = await Task.withUnsafeContinuation { continuation in
+  let _: String = await withUnsafeContinuation { continuation in
     continuation.resume(returning: "")
   }
 }
 
 func test_unsafeThrowingContinuations() async {
-  let _: String = await try Task.withUnsafeThrowingContinuation { continuation in
+  let _: String = await try withUnsafeThrowingContinuation { continuation in
     continuation.resume(returning: "")
   }
 
-  let _: String = await try Task.withUnsafeThrowingContinuation { continuation in
+  let _: String = await try withUnsafeThrowingContinuation { continuation in
     continuation.resume(throwing: MyError())
   }