Add deprecation warning.

src/Twig/TwigSortTokenParser.php

@@ -19,6 +19,7 @@ final class TwigSortTokenParser extends AbstractTokenParser {
    * {@inheritdoc}
    */
   public function parse(Token $token): Node {
+    \trigger_error('The sort tag is deprecated in 3.6.0 and will be removed in 4.x, use the sort_namespaces twig filter.', \E_USER_WARNING);
     $this->parser->getStream()->expect(Token::BLOCK_END_TYPE);
     $body = $this->parser->subparse(
       static fn (Token $token): bool => $token->test('endsort'),

tests/unit/TwigEnvironmentTest.php

@@ -6,6 +6,7 @@
 
 use DrupalCodeGenerator\Twig\TwigEnvironment;
 use PHPUnit\Framework\TestCase;
+use Twig\Error\SyntaxError;
 use Twig\Loader\FilesystemLoader;
 
 /**
@@ -20,8 +21,20 @@ public function testTwigEnvironment(): void {
     $twig_loader = new FilesystemLoader(__DIR__);
     $twig = new TwigEnvironment($twig_loader);
     $expected = \file_get_contents(__DIR__ . '/_twig_environment_fixture.txt');
-    $result = $twig->render('twig-environment-template.twig', []);
+    \error_reporting(\error_reporting() & ~ \E_USER_WARNING);
+    $result = $twig->render('twig-environment-template.twig');
     self::assertSame($expected, $result);
   }
 
+  /**
+   * Test callback.
+   */
+  public function testDeprecateTagTwigEnvironment(): void {
+    $twig_loader = new FilesystemLoader(__DIR__);
+    $twig = new TwigEnvironment($twig_loader);
+    $this->expectException(SyntaxError::class);
+    $this->expectExceptionMessage('An exception has been thrown during the compilation of a template ("The sort tag is deprecated in 3.6.0 and will be removed in 4.x, use the sort_namespaces twig filter.") in "twig-environment-template.twig".');
+    $twig->render('twig-environment-template.twig');
+  }
+
 }