Replace Stringable|string argument types with string-only

Methods that previously accepted `Stringable|string` as argument types
now only support `string`.

`Stringable` was added for convenience so that someone could do,
for example

```php
$user = $auth->getUser('uid');
$auth->updateUser($user, [...]);
```

While convenient, this adds overhead when processing these arguments.
For example, if a method expects a non-empty string, the SDK would
have to do a `trim((string) $arg)` and check if it's empty.

With this change, we can rely only on a `@var non-empty-string $arg`
docblock annotation.

```php
$user = $auth->getUser('uid');
$auth->updateUser($user->uid, [...]);
```

Author: jeromegamez

CHANGELOG.md

@@ -12,6 +12,7 @@ If it saves you or your team time, please consider [sponsoring its development](
 * [Firebase Dynamic Links was shut down on August 25th, 2025](https://firebase.google.com/support/dynamic-links-faq)
   and has been removed from the SDK.
 * Deprecated classes, methods and class constants have been removed.
+* Replaced `Stringable|string` argument types with `string`-only
 
 See **[UPGRADE-8.0](UPGRADE-8.0.md) for more details on the changes between 7.x and 8.0.**
 

UPGRADE-8.0.md

@@ -46,7 +46,6 @@
 use Lcobucci\JWT\UnencryptedToken;
 use Psr\Clock\ClockInterface;
 use Psr\Http\Message\ResponseInterface;
-use Stringable;
 use Throwable;
 use Traversable;
 
@@ -76,7 +75,7 @@ public function __construct(
         $this->jwtParser = new Parser(new JoseEncoder());
     }
 
-    public function getUser(Stringable|string $uid): UserRecord
+    public function getUser(string $uid): UserRecord
     {
         $uid = Uid::fromString($uid)->value;
 
@@ -91,7 +90,7 @@ public function getUser(Stringable|string $uid): UserRecord
 
     public function getUsers(array $uids): array
     {
-        $uids = array_map(static fn(\Stringable|string $uid): string => Uid::fromString($uid)->value, $uids);
+        $uids = array_map(static fn(string $uid): string => Uid::fromString($uid)->value, $uids);
 
         $users = array_fill_keys($uids, null);
 
@@ -161,7 +160,7 @@ public function createUser(array|CreateUser $properties): UserRecord
         return $this->getUserRecordFromResponseAfterUserUpdate($response);
     }
 
-    public function updateUser(Stringable|string $uid, array|UpdateUser $properties): UserRecord
+    public function updateUser(string $uid, array|UpdateUser $properties): UserRecord
     {
         $request = $properties instanceof UpdateUser
             ? $properties
@@ -174,7 +173,7 @@ public function updateUser(Stringable|string $uid, array|UpdateUser $properties)
         return $this->getUserRecordFromResponseAfterUserUpdate($response);
     }
 
-    public function createUserWithEmailAndPassword(Stringable|string $email, Stringable|string $password): UserRecord
+    public function createUserWithEmailAndPassword(string $email, string $password): UserRecord
     {
         return $this->createUser(
             CreateUser::new()
@@ -183,9 +182,9 @@ public function createUserWithEmailAndPassword(Stringable|string $email, Stringa
         );
     }
 
-    public function getUserByEmail(Stringable|string $email): UserRecord
+    public function getUserByEmail(string $email): UserRecord
     {
-        $email = Email::fromString((string) $email)->value;
+        $email = Email::fromString($email)->value;
 
         $response = $this->client->getUserByEmail($email);
 
@@ -198,10 +197,8 @@ public function getUserByEmail(Stringable|string $email): UserRecord
         return $userRecord;
     }
 
-    public function getUserByPhoneNumber(Stringable|string $phoneNumber): UserRecord
+    public function getUserByPhoneNumber(string $phoneNumber): UserRecord
     {
-        $phoneNumber = (string) $phoneNumber;
-
         $response = $this->client->getUserByPhoneNumber($phoneNumber);
 
         $userRecord = self::getFirstUserRecordFromUserListResponse($response);
@@ -213,11 +210,8 @@ public function getUserByPhoneNumber(Stringable|string $phoneNumber): UserRecord
         return $userRecord;
     }
 
-    public function getUserByProviderUid(Stringable|string $providerId, Stringable|string $providerUid): UserRecord
+    public function getUserByProviderUid(string $providerId, string $providerUid): UserRecord
     {
-        $providerId = (string) $providerId;
-        $providerUid = (string) $providerUid;
-
         $response = $this->client->getUserByProviderUid($providerId, $providerUid);
 
         $userRecord = self::getFirstUserRecordFromUserListResponse($response);
@@ -234,27 +228,27 @@ public function createAnonymousUser(): UserRecord
         return $this->createUser(CreateUser::new());
     }
 
-    public function changeUserPassword(Stringable|string $uid, Stringable|string $newPassword): UserRecord
+    public function changeUserPassword(string $uid, string $newPassword): UserRecord
     {
         return $this->updateUser($uid, UpdateUser::new()->withClearTextPassword($newPassword));
     }
 
-    public function changeUserEmail(Stringable|string $uid, Stringable|string $newEmail): UserRecord
+    public function changeUserEmail(string $uid, string $newEmail): UserRecord
     {
         return $this->updateUser($uid, UpdateUser::new()->withEmail($newEmail));
     }
 
-    public function enableUser(Stringable|string $uid): UserRecord
+    public function enableUser(string $uid): UserRecord
     {
         return $this->updateUser($uid, UpdateUser::new()->markAsEnabled());
     }
 
-    public function disableUser(Stringable|string $uid): UserRecord
+    public function disableUser(string $uid): UserRecord
     {
         return $this->updateUser($uid, UpdateUser::new()->markAsDisabled());
     }
 
-    public function deleteUser(Stringable|string $uid): void
+    public function deleteUser(string $uid): void
     {
         $uid = Uid::fromString($uid)->value;
 
@@ -277,9 +271,9 @@ public function deleteUsers(iterable $uids, bool $forceDeleteEnabledUsers = fals
         return DeleteUsersResult::fromRequestAndResponse($request, $response);
     }
 
-    public function getEmailActionLink(string $type, Stringable|string $email, $actionCodeSettings = null, ?string $locale = null): string
+    public function getEmailActionLink(string $type, string $email, $actionCodeSettings = null, ?string $locale = null): string
     {
-        $email = Email::fromString((string) $email)->value;
+        $email = Email::fromString($email)->value;
 
         if ($actionCodeSettings === null) {
             $actionCodeSettings = ValidatedActionCodeSettings::empty();
@@ -292,9 +286,9 @@ public function getEmailActionLink(string $type, Stringable|string $email, $acti
         return $this->client->getEmailActionLink($type, $email, $actionCodeSettings, $locale);
     }
 
-    public function sendEmailActionLink(string $type, Stringable|string $email, $actionCodeSettings = null, ?string $locale = null): void
+    public function sendEmailActionLink(string $type, string $email, $actionCodeSettings = null, ?string $locale = null): void
     {
-        $email = Email::fromString((string) $email)->value;
+        $email = Email::fromString($email)->value;
 
         if ($actionCodeSettings === null) {
             $actionCodeSettings = ValidatedActionCodeSettings::empty();
@@ -330,45 +324,45 @@ public function sendEmailActionLink(string $type, Stringable|string $email, $act
         $this->client->sendEmailActionLink($type, $email, $actionCodeSettings, $locale, $idToken);
     }
 
-    public function getEmailVerificationLink(Stringable|string $email, $actionCodeSettings = null, ?string $locale = null): string
+    public function getEmailVerificationLink(string $email, $actionCodeSettings = null, ?string $locale = null): string
     {
         return $this->getEmailActionLink('VERIFY_EMAIL', $email, $actionCodeSettings, $locale);
     }
 
-    public function sendEmailVerificationLink(Stringable|string $email, $actionCodeSettings = null, ?string $locale = null): void
+    public function sendEmailVerificationLink(string $email, $actionCodeSettings = null, ?string $locale = null): void
     {
         $this->sendEmailActionLink('VERIFY_EMAIL', $email, $actionCodeSettings, $locale);
     }
 
-    public function getPasswordResetLink(Stringable|string $email, $actionCodeSettings = null, ?string $locale = null): string
+    public function getPasswordResetLink(string $email, $actionCodeSettings = null, ?string $locale = null): string
     {
         return $this->getEmailActionLink('PASSWORD_RESET', $email, $actionCodeSettings, $locale);
     }
 
-    public function sendPasswordResetLink(Stringable|string $email, $actionCodeSettings = null, ?string $locale = null): void
+    public function sendPasswordResetLink(string $email, $actionCodeSettings = null, ?string $locale = null): void
     {
         $this->sendEmailActionLink('PASSWORD_RESET', $email, $actionCodeSettings, $locale);
     }
 
-    public function getSignInWithEmailLink(Stringable|string $email, $actionCodeSettings = null, ?string $locale = null): string
+    public function getSignInWithEmailLink(string $email, $actionCodeSettings = null, ?string $locale = null): string
     {
         return $this->getEmailActionLink('EMAIL_SIGNIN', $email, $actionCodeSettings, $locale);
     }
 
-    public function sendSignInWithEmailLink(Stringable|string $email, $actionCodeSettings = null, ?string $locale = null): void
+    public function sendSignInWithEmailLink(string $email, $actionCodeSettings = null, ?string $locale = null): void
     {
         $this->sendEmailActionLink('EMAIL_SIGNIN', $email, $actionCodeSettings, $locale);
     }
 
-    public function setCustomUserClaims(Stringable|string $uid, ?array $claims): void
+    public function setCustomUserClaims(string $uid, ?array $claims): void
     {
         $uid = Uid::fromString($uid)->value;
         $claims ??= [];
 
         $this->client->setCustomUserClaims($uid, $claims);
     }
 
-    public function createCustomToken(Stringable|string $uid, array $claims = [], $ttl = 3600): UnencryptedToken
+    public function createCustomToken(string $uid, array $claims = [], $ttl = 3600): UnencryptedToken
     {
         if ($this->tokenGenerator === null) {
             throw new AuthError('Custom Token Generation is disabled because the current credentials do not permit it');
@@ -507,7 +501,7 @@ public function confirmPasswordReset(string $oobCode, $newPassword, bool $invali
         return $email;
     }
 
-    public function revokeRefreshTokens(Stringable|string $uid): void
+    public function revokeRefreshTokens(string $uid): void
     {
         $uid = Uid::fromString($uid)->value;
 
@@ -518,12 +512,7 @@ public function unlinkProvider($uid, $provider): UserRecord
     {
         $uid = Uid::fromString($uid)->value;
 
-        $provider = array_values(
-            array_filter(
-                array_map(strval(...), (array) $provider),
-                static fn(string $value): bool => $value !== '',
-            ),
-        );
+        $provider = array_map(strval(...), (array) $provider);
 
         $response = $this->client->unlinkProvider($uid, $provider);
 
@@ -533,7 +522,7 @@ public function unlinkProvider($uid, $provider): UserRecord
     public function signInAsUser($user, ?array $claims = null): SignInResult
     {
         $claims ??= [];
-        $uid = $user instanceof UserRecord ? $user->uid : (string) $user;
+        $uid = $user instanceof UserRecord ? $user->uid : $user;
 
         try {
             $customToken = $this->createCustomToken($uid, $claims);
@@ -560,15 +549,15 @@ public function signInWithRefreshToken(string $refreshToken): SignInResult
 
     public function signInWithEmailAndPassword($email, $clearTextPassword): SignInResult
     {
-        $email = Email::fromString((string) $email)->value;
+        $email = Email::fromString($email)->value;
         $clearTextPassword = ClearTextPassword::fromString($clearTextPassword)->value;
 
         return $this->client->handleSignIn(SignInWithEmailAndPassword::fromValues($email, $clearTextPassword));
     }
 
     public function signInWithEmailAndOobCode($email, string $oobCode): SignInResult
     {
-        $email = Email::fromString((string) $email)->value;
+        $email = Email::fromString($email)->value;
 
         return $this->client->handleSignIn(SignInWithEmailAndOobCode::fromValues($email, $oobCode));
     }
@@ -591,7 +580,6 @@ public function signInAnonymously(): SignInResult
 
     public function signInWithIdpAccessToken($provider, string $accessToken, $redirectUrl = null, ?string $oauthTokenSecret = null, ?string $linkingIdToken = null, ?string $rawNonce = null): SignInResult
     {
-        $provider = (string) $provider;
         $redirectUrl = trim((string) ($redirectUrl ?? 'http://localhost'));
         $linkingIdToken = trim((string) $linkingIdToken);
         $oauthTokenSecret = trim((string) $oauthTokenSecret);
@@ -620,7 +608,6 @@ public function signInWithIdpAccessToken($provider, string $accessToken, $redire
 
     public function signInWithIdpIdToken($provider, $idToken, $redirectUrl = null, ?string $linkingIdToken = null, ?string $rawNonce = null): SignInResult
     {
-        $provider = trim((string) $provider);
         $redirectUrl = trim((string) ($redirectUrl ?? 'http://localhost'));
         $linkingIdToken = trim((string) $linkingIdToken);
         $rawNonce = trim((string) $rawNonce);

src/Firebase/Auth.php

@@ -20,7 +20,6 @@
 use Kreait\Firebase\Request\UpdateUser;
 use Psr\Clock\ClockInterface;
 use Psr\Http\Message\ResponseInterface;
-use Stringable;
 use Throwable;
 
 use function array_filter;
@@ -239,7 +238,7 @@ public function revokeRefreshTokens(string $uid): ResponseInterface
     }
 
     /**
-     * @param list<Stringable|non-empty-string> $providers
+     * @param list<non-empty-string> $providers
      *
      * @throws AuthException
      */

src/Firebase/Auth/ApiClient.php

@@ -5,7 +5,6 @@
 namespace Kreait\Firebase\Auth;
 
 use Kreait\Firebase\Value\Email;
-use Stringable;
 
 /**
  * @internal
@@ -21,9 +20,9 @@ private function __construct(
     ) {
     }
 
-    public static function new(string $type, Stringable|string $email, ActionCodeSettings $settings, ?string $tenantId = null, ?string $locale = null): self
+    public static function new(string $type, string $email, ActionCodeSettings $settings, ?string $tenantId = null, ?string $locale = null): self
     {
-        $email = Email::fromString((string) $email)->value;
+        $email = Email::fromString($email)->value;
 
         return new self($tenantId, $locale, $type, $email, $settings);
     }

src/Firebase/Auth/CreateActionLink.php

@@ -13,7 +13,6 @@
 use Lcobucci\JWT\Encoding\JoseEncoder;
 use Lcobucci\JWT\Token;
 use Lcobucci\JWT\Token\Parser;
-use Stringable;
 
 /**
  * @internal
@@ -31,13 +30,15 @@ public function __construct(private SignBlobInterface $signer, private ?string $
     }
 
     /**
-     * @param Stringable|string $uid
+     * @param non-empty-string $uid
      * @param array<non-empty-string, mixed> $claims
      *
      * @throws AuthError
      */
-    public function createCustomToken($uid, array $claims = [], ?DateTimeInterface $expiresAt = null): Token
+    public function createCustomToken(string $uid, ?array $claims = null, ?DateTimeInterface $expiresAt = null): Token
     {
+        $claims ??= [];
+
         $now = new DateTimeImmutable();
         $expiresAt = ($expiresAt !== null)
             ? DT::toUTCDateTimeImmutable($expiresAt)
@@ -50,7 +51,7 @@ public function createCustomToken($uid, array $claims = [], ?DateTimeInterface $
             'aud' => 'https://identitytoolkit.googleapis.com/google.identity.identitytoolkit.v1.IdentityToolkit',
             'iat' => $now->getTimestamp(),
             'exp' => $expiresAt->getTimestamp(),
-            'uid' => (string) $uid,
+            'uid' => $uid,
         ];
 
         if ($this->tenantId !== null) {

src/Firebase/Auth/CustomTokenViaGoogleCredentials.php

@@ -6,7 +6,6 @@
 
 use Kreait\Firebase\Exception\InvalidArgumentException;
 use Kreait\Firebase\Value\Uid;
-use Stringable;
 
 /**
  * @internal
@@ -23,7 +22,7 @@ private function __construct(
     }
 
     /**
-     * @param iterable<Stringable|string> $uids
+     * @param iterable<string> $uids
      */
     public static function withUids(iterable $uids, bool $forceDeleteEnabledUsers = false): self
     {