[stdlib] Add a non-failable initializer

Author: benrimmington

stdlib/public/Distributed/DistributedActor.swift

@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2020 Apple Inc. and the Swift project authors
+// Copyright (c) 2020 - 2023 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
@@ -290,7 +290,7 @@ extension CodingUserInfoKey {
   /// Forgetting to set this key will result in that initializer throwing, because
   /// an actor system is required in order to call ``DistributedActor/resolve(id:using:)`` using it.
   @available(SwiftStdlib 5.7, *)
-  public static let actorSystemKey = CodingUserInfoKey(rawValue: "$distributed_actor_system")!
+  public static let actorSystemKey = CodingUserInfoKey("$distributed_actor_system")
 }
 
 @available(SwiftStdlib 5.7, *)

stdlib/public/core/Codable.swift

@@ -3137,6 +3137,14 @@ public struct CodingUserInfoKey: RawRepresentable, Equatable, Hashable, Sendable
     self.rawValue = rawValue
   }
 
+  /// Creates a new instance with the given raw value.
+  ///
+  /// - parameter rawValue: The value of the key.
+  @_alwaysEmitIntoClient
+  public init(_ rawValue: String) {
+    self.init(rawValue: rawValue)!
+  }
+
   /// Returns a Boolean value indicating whether the given keys are equal.
   ///
   /// - parameter lhs: The key to compare against.