Concurrency: Address new -strict-memory-safety warnings.

Author: tshortli

stdlib/public/Concurrency/ContinuousClock.swift

@@ -144,7 +144,9 @@ extension ContinuousClock: Clock {
 extension ContinuousClock {
   @available(SwiftStdlib 5.7, *)
   @_alwaysEmitIntoClient
-  public var systemEpoch: Instant { unsafeBitCast(Duration.seconds(0), to: Instant.self) }
+  public var systemEpoch: Instant {
+    unsafe unsafeBitCast(Duration.seconds(0), to: Instant.self)
+  }
 }
 
 @available(SwiftStdlib 5.7, *)

stdlib/public/Concurrency/Executor.swift

@@ -385,7 +385,7 @@ extension SerialExecutor {
   #if SWIFT_CONCURRENCY_USES_DISPATCH
   @available(SwiftStdlib 6.2, *)
   private var _dispatchQueue: OpaquePointer? {
-    return _getDispatchQueueForExecutor(self.asUnownedSerialExecutor())
+    return unsafe _getDispatchQueueForExecutor(self.asUnownedSerialExecutor())
   }
   #endif
 
@@ -395,8 +395,8 @@ extension SerialExecutor {
       return true
     }
     #if SWIFT_CONCURRENCY_USES_DISPATCH
-    if let rhsQueue = rhs._dispatchQueue {
-      if let ourQueue = _dispatchQueue, ourQueue == rhsQueue {
+    if let rhsQueue = unsafe rhs._dispatchQueue {
+      if let ourQueue = unsafe _dispatchQueue, ourQueue == rhsQueue {
         return true
       }
       return false

stdlib/public/Concurrency/SuspendingClock.swift

@@ -132,7 +132,9 @@ extension SuspendingClock: Clock {
 extension SuspendingClock {
   @available(SwiftStdlib 5.7, *)
   @_alwaysEmitIntoClient
-  public var systemEpoch: Instant { unsafeBitCast(Duration.seconds(0), to: Instant.self) }
+  public var systemEpoch: Instant {
+    unsafe unsafeBitCast(Duration.seconds(0), to: Instant.self)
+  }
 }
 
 @available(SwiftStdlib 5.7, *)