[DependencyInjection][Config][Routing] Deprecate using $this or the internal scope of the loader from PHP config files

Author: nicolas-grekas

CHANGELOG.md

@@ -11,6 +11,7 @@ CHANGELOG
  * Deprecate registering a service without a class when its id is a non-existing FQCN
  * Allow multiple `#[AsDecorator]` attributes
  * Handle returning arrays and config-builders from config files
+ * Deprecate using `$this` or its internal scope from PHP config files; use the `$loader` variable instead
 
 7.3
 ---

Loader/PhpFileLoader.php

@@ -61,13 +61,25 @@ public function load(mixed $resource, ?string $type = null): mixed
         class_exists(ContainerConfigurator::class);
 
         // the closure forbids access to the private scope in the included file
-        $load = \Closure::bind(function ($path, $env) use ($container, $loader, $resource, $type) {
+        $load = \Closure::bind(static function ($path, $env) use ($container, $loader, $resource, $type) {
             return include $path;
-        }, $this, ProtectedPhpFileLoader::class);
+        }, null, null);
 
         try {
-            if (1 === $result = $load($path, $this->env)) {
-                $result = null;
+            try {
+                if (1 === $result = $load($path, $this->env)) {
+                    $result = null;
+                }
+            } catch (\Error $e) {
+                $load = \Closure::bind(function ($path, $env) use ($container, $loader, $resource, $type) {
+                    return include $path;
+                }, $this, ProtectedPhpFileLoader::class);
+
+                if (1 === $result = $load($path, $this->env)) {
+                    $result = null;
+                }
+
+                trigger_deprecation('symfony/dependency-injection', '8.1', 'Using `$this` or its internal scope in config files is deprecated, use the `$loader` variable instead in "%s" on line %d.', $e->getFile(), $e->getLine());
             }
 
             if (\is_object($result) && \is_callable($result)) {

Tests/Fixtures/config/legacy_internal_scope.php

@@ -0,0 +1,4 @@
+<?php
+
+// access the loader's internal scope to trigger deprecation
+$this->supports('dummy.php');

Tests/Loader/PhpFileLoaderTest.php

@@ -15,6 +15,8 @@
 require_once __DIR__.'/../Fixtures/includes/fixture_app_services.php';
 
 use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\Attributes\Group;
+use PHPUnit\Framework\Attributes\IgnoreDeprecations;
 use PHPUnit\Framework\TestCase;
 use Symfony\Component\Config\Builder\ConfigBuilderGenerator;
 use Symfony\Component\Config\FileLocator;
@@ -365,4 +367,16 @@ public function testReturnsGenerator()
         $loader->load('return_generator.php');
         $this->assertSame([['color' => 'red']], $container->getExtensionConfig('acme'));
     }
+
+    #[IgnoreDeprecations]
+    #[Group('legacy')]
+    public function testTriggersDeprecationWhenAccessingLoaderInternalScope()
+    {
+        $fixtures = realpath(__DIR__.'/../Fixtures');
+        $loader = new PhpFileLoader(new ContainerBuilder(), new FileLocator($fixtures.'/config'));
+
+        $this->expectUserDeprecationMessageMatches('{^Since symfony/dependency-injection 8.1: Using \`\$this\` or its internal scope in config files is deprecated, use the \`\$loader\` variable instead in ".+" on line \d+\.$}');
+
+        $loader->load('legacy_internal_scope.php');
+    }
 }