minor symfony#57571 Add return type to __toString() methods (seriquynh)

This PR was merged into the 7.2 branch.

Discussion
----------

Add return type to `__toString()` methods

| Q             | A
| ------------- | ---
| Branch?       | 7.2
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Issues        | N/A
| License       | MIT

CompletionInput::__toString() method should have string as the return type, synchronized with it's parent class.

Commits
-------

3934380 Add return type to __toString() methods

Author: nicolas-grekas

src/Symfony/Component/Console/Completion/CompletionInput.php

@@ -226,7 +226,7 @@ private function isCursorFree(): bool
         return $this->currentIndex >= $nrOfTokens;
     }
 
-    public function __toString()
+    public function __toString(): string
     {
         $str = '';
         foreach ($this->tokens as $i => $token) {

src/Symfony/Component/DependencyInjection/Tests/EnvVarProcessorTest.php

@@ -871,7 +871,7 @@ public function loadEnvVars(): array
                         'FOO_ENV_LOADER' => '123',
                         'BAZ_ENV_LOADER' => '',
                         'LAZY_ENV_LOADER' => new class() {
-                            public function __toString()
+                            public function __toString(): string
                             {
                                 return '';
                             }
@@ -888,7 +888,7 @@ public function loadEnvVars(): array
                         'BAR_ENV_LOADER' => '456',
                         'BAZ_ENV_LOADER' => '567',
                         'LAZY_ENV_LOADER' => new class() {
-                            public function __toString()
+                            public function __toString(): string
                             {
                                 return '678';
                             }

src/Symfony/Component/HttpClient/Tests/MockHttpClientTest.php

@@ -519,7 +519,7 @@ public function testStringableBodyParam()
         $client = new MockHttpClient();
 
         $param = new class() {
-            public function __toString()
+            public function __toString(): string
             {
                 return 'bar';
             }

src/Symfony/Component/Routing/Tests/Generator/UrlGeneratorTest.php

@@ -1076,7 +1076,7 @@ protected function getRoutes($name, Route $route)
 
 class StringableObject
 {
-    public function __toString()
+    public function __toString(): string
     {
         return 'bar';
     }
@@ -1086,7 +1086,7 @@ class StringableObjectWithPublicProperty
 {
     public $foo = 'property';
 
-    public function __toString()
+    public function __toString(): string
     {
         return 'bar';
     }

src/Symfony/Component/Security/Http/Tests/Authenticator/FormLoginAuthenticatorTest.php

@@ -176,7 +176,7 @@ public function testHandleNonStringPasswordWithArray(bool $postOnly)
     public function testHandleNonStringPasswordWithToString(bool $postOnly)
     {
         $passwordObject = new class() {
-            public function __toString()
+            public function __toString(): string
             {
                 return 's$cr$t';
             }