[Auth] Fix Xcode 26.2 build warning

FirebaseAuth/CHANGELOG.md

@@ -1,5 +1,6 @@
 # Unreleased
 - [fixed] Add a mechanism to prevent concurrent token refreshes. (#15474)
+- [fixed] Fix "weak never mutated" build warning introduced in Xcode 26.2.
 
 # 12.2.0
 - [added] Added TOTP support for macOS.

FirebaseAuth/Sources/Swift/Auth/Auth.swift

@@ -1938,30 +1938,30 @@ extension Auth: AuthInterop {
         "for the new token.")
     }
     autoRefreshScheduled = true
-    weak var weakSelf = self
-    authDispatcher.dispatch(afterDelay: delay, queue: kAuthGlobalWorkQueue) {
-      guard let strongSelf = weakSelf else {
+    authDispatcher.dispatch(afterDelay: delay, queue: kAuthGlobalWorkQueue) { [weak self] in
+      guard let self else {
         return
       }
-      guard strongSelf._currentUser?.rawAccessToken() == accessToken else {
+      guard self._currentUser?.rawAccessToken() == accessToken else {
         // Another auto refresh must have been scheduled, so keep _autoRefreshScheduled unchanged.
         return
       }
-      strongSelf.autoRefreshScheduled = false
-      if strongSelf.isAppInBackground {
+      self.autoRefreshScheduled = false
+      if self.isAppInBackground {
         return
       }
-      let uid = strongSelf._currentUser?.uid
-      strongSelf._currentUser?
-        .internalGetToken(forceRefresh: true, backend: strongSelf.backend) { token, error in
-          if strongSelf._currentUser?.uid != uid {
+      let uid = self._currentUser?.uid
+      self._currentUser?
+        .internalGetToken(forceRefresh: true, backend: self.backend) { [weak self] token, error in
+          guard let self else { return }
+          if self._currentUser?.uid != uid {
             return
           }
           if error != nil {
             // Kicks off exponential back off logic to retry failed attempt. Starts with one minute
             // delay (60 seconds) if this is the first failed attempt.
             let rescheduleDelay = retry ? min(delay * 2, 16 * 60) : 60
-            strongSelf.scheduleAutoTokenRefresh(withDelay: rescheduleDelay, retry: true)
+            self.scheduleAutoTokenRefresh(withDelay: rescheduleDelay, retry: true)
           }
         }
     }