[DependencyInjection] Fix lazy-proxying final classes

Author: nicolas-grekas

LazyProxy/PhpDumper/LazyServiceDumper.php

@@ -123,12 +123,13 @@ public function getProxyCode(Definition $definition, string $id = null): string
                 if (!interface_exists($tag['interface']) && !class_exists($tag['interface'], false)) {
                     throw new InvalidArgumentException(sprintf('Invalid definition for service "%s": several "proxy" tags found but "%s" is not an interface.', $id ?? $definition->getClass(), $tag['interface']));
                 }
+                if (!is_a($class->name, $tag['interface'], true)) {
+                    throw new InvalidArgumentException(sprintf('Invalid "proxy" tag for service "%s": class "%s" doesn\'t implement "%s".', $id ?? $definition->getClass(), $definition->getClass(), $tag['interface']));
+                }
                 $interfaces[] = new \ReflectionClass($tag['interface']);
             }
 
-            if (1 === \count($interfaces) && !$interfaces[0]->isInterface()) {
-                $class = array_pop($interfaces);
-            }
+            $class = 1 === \count($interfaces) && !$interfaces[0]->isInterface() ? array_pop($interfaces) : null;
         } elseif ($class->isInterface()) {
             $interfaces = [$class];
             $class = null;

Tests/LazyProxy/PhpDumper/LazyServiceDumperTest.php

@@ -14,6 +14,7 @@
 use PHPUnit\Framework\TestCase;
 use Psr\Container\ContainerInterface;
 use Symfony\Component\DependencyInjection\Definition;
+use Symfony\Component\DependencyInjection\Exception\InvalidArgumentException;
 use Symfony\Component\DependencyInjection\LazyProxy\PhpDumper\LazyServiceDumper;
 
 class LazyServiceDumperTest extends TestCase
@@ -26,4 +27,42 @@ public function testProxyInterface()
         $this->assertTrue($dumper->isProxyCandidate($definition));
         $this->assertStringContainsString('function get(', $dumper->getProxyCode($definition));
     }
+
+    public function testFinalClassInterface()
+    {
+        $dumper = new LazyServiceDumper();
+        $definition = (new Definition(TestContainer::class))
+            ->setLazy(true)
+            ->addTag('proxy', ['interface' => ContainerInterface::class]);
+
+        $this->assertTrue($dumper->isProxyCandidate($definition));
+        $this->assertStringContainsString('function get(', $dumper->getProxyCode($definition));
+    }
+
+    public function testInvalidClass()
+    {
+        $dumper = new LazyServiceDumper();
+        $definition = (new Definition(\stdClass::class))
+            ->setLazy(true)
+            ->addTag('proxy', ['interface' => ContainerInterface::class]);
+
+        $this->assertTrue($dumper->isProxyCandidate($definition));
+
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Invalid "proxy" tag for service "stdClass": class "stdClass" doesn\'t implement "Psr\Container\ContainerInterface".');
+        $dumper->getProxyCode($definition);
+    }
+}
+
+final class TestContainer implements ContainerInterface
+{
+    public function has(string $key): bool
+    {
+        return true;
+    }
+
+    public function get(string $key): string
+    {
+        return $key;
+    }
 }