Add _unsafeInheritExecutor_ version of TaskLocal.withValue

Author: DougGregor

stdlib/public/Concurrency/TaskLocal.swift

@@ -215,14 +215,21 @@ public final class TaskLocal<Value: Sendable>: Sendable, CustomStringConvertible
       file: file, line: line)
   }
 
-  @usableFromInline
+  // Note: hack to stage out @_unsafeInheritExecutor forms of various functions
+  // in favor of #isolation. The _unsafeInheritExecutor_ prefix is meaningful
+  // to the type checker.
+  //
+  // This function also doubles as an ABI-compatibility shim predating the
+  // introduction of #isolation.
   @discardableResult
   @_unsafeInheritExecutor // ABI compatibility with Swift 5.1
   @available(SwiftStdlib 5.1, *)
   @_silgen_name("$ss9TaskLocalC9withValue_9operation4file4lineqd__x_qd__yYaKXESSSutYaKlF")
-  internal func __abi_withValue<R>(_ valueDuringOperation: Value,
-                                   operation: () async throws -> R,
-                                   file: String = #fileID, line: UInt = #line) async rethrows -> R {
+  public func _unsafeInheritExecutor_withValue<R>(
+    _ valueDuringOperation: Value,
+    operation: () async throws -> R,
+    file: String = #fileID, line: UInt = #line
+  ) async rethrows -> R {
     return try await withValueImpl(valueDuringOperation, operation: operation, file: file, line: line)
   }
 

test/Concurrency/unsafe_inherit_executor.swift

@@ -1,7 +1,7 @@
-// RUN: %target-swift-frontend -emit-sil -o /dev/null -verify -disable-availability-checking %s
-// RUN: %target-swift-frontend -emit-sil -o /dev/null -verify -disable-availability-checking %s -strict-concurrency=targeted
-// RUN: %target-swift-frontend -emit-sil -o /dev/null -verify -disable-availability-checking %s -strict-concurrency=complete
-// RUN: %target-swift-frontend -emit-sil -o /dev/null -verify -disable-availability-checking %s -strict-concurrency=complete -enable-upcoming-feature RegionBasedIsolation
+// RUN: %target-swift-frontend -plugin-path %swift-plugin-dir -emit-sil -o /dev/null -verify -disable-availability-checking %s
+// RUN: %target-swift-frontend -plugin-path %swift-plugin-dir -emit-sil -o /dev/null -verify -disable-availability-checking %s -strict-concurrency=targeted
+// RUN: %target-swift-frontend -plugin-path %swift-plugin-dir -emit-sil -o /dev/null -verify -disable-availability-checking %s -strict-concurrency=complete
+// RUN: %target-swift-frontend -plugin-path %swift-plugin-dir -emit-sil -o /dev/null -verify -disable-availability-checking %s -strict-concurrency=complete -enable-upcoming-feature RegionBasedIsolation
 
 // REQUIRES: asserts
 
@@ -83,6 +83,11 @@ func unsafeCallerAvoidsNewLoop(x: some AsyncSequence<Int, Never>) async throws {
 // some concurrency library functions.
 // -------------------------------------------------------------------------
 
+enum TL {
+  @TaskLocal
+  static var string: String = "<undefined>"
+}
+
 @_unsafeInheritExecutor
 func unsafeCallerAvoidsNewLoop() async throws {
   // expected-warning@-1{{@_unsafeInheritExecutor attribute is deprecated; consider an 'isolated' parameter defaulted to '#isolation' instead}}
@@ -107,4 +112,8 @@ func unsafeCallerAvoidsNewLoop() async throws {
     5
   } onCancel: {
   }
+
+  TL.$string.withValue("hello") {
+    print(TL.string)
+  }
 }