Review from @dmolineus

core-bundle/src/DependencyInjection/Configuration.php

@@ -73,7 +73,7 @@ public function getConfigTreeBuilder(): TreeBuilder
                 ->end()
                 ->booleanNode('prepend_locale')
                     ->info('Whether or not to add the page language to the URL.')
-                    ->setDeprecated('The language prefix is configured per root page since Contao 4.10')
+                    ->setDeprecated('The language prefix is configured per root page since Contao 4.10. Enabling this option will activate legacy routing.')
                 ->end()
                 ->booleanNode('pretty_error_screens')
                     ->info('Show customizable, pretty error screens instead of the default PHP error messages.')
@@ -108,7 +108,7 @@ static function (string $v): int {
                     ->defaultValue('css,csv,html,ini,js,json,less,md,scss,svg,svgz,txt,xliff,xml,yml,yaml')
                 ->end()
                 ->scalarNode('url_suffix')
-                    ->setDeprecated('The URL suffix is configured per root page since Contao 4.10')
+                    ->setDeprecated('The URL suffix is configured per root page since Contao 4.10. Enabling this option will activate legacy routing.')
                 ->end()
                 ->scalarNode('web_dir')
                     ->info('Absolute path to the web directory. Defaults to %kernel.project_dir%/web.')

core-bundle/src/Event/FilterPageTypeEvent.php

@@ -39,7 +39,7 @@ public function getDataContainer(): DataContainer
 
     public function getOptions(): array
     {
-        return $this->options;
+        return array_values($this->options);
     }
 
     public function setOptions(array $options): self

core-bundle/src/Exception/ContentRouteNotFoundException.php

@@ -18,12 +18,21 @@
 
 class ContentRouteNotFoundException extends RouteNotFoundException
 {
+    private $content;
+
     public function __construct($content, $code = 0, \Throwable $previous = null)
     {
-        parent::__construct('No route found for '.static::getRouteDebugMessage($content), $code, $previous);
+        parent::__construct('No route found for '.$this->getRouteDebugMessage($content), $code, $previous);
+
+        $this->content = $content;
+    }
+
+    public function getContent()
+    {
+        return $this->content;
     }
 
-    public static function getRouteDebugMessage($content): string
+    private function getRouteDebugMessage($content): string
     {
         if (is_scalar($content)) {
             return $content;
@@ -45,6 +54,6 @@ public static function getRouteDebugMessage($content): string
             return \get_class($content);
         }
 
-        return 'null route';
+        return 'unknown route';
     }
 }

core-bundle/src/Resources/contao/languages/en/tl_page.xlf

@@ -14,6 +14,12 @@
       <trans-unit id="tl_page.alias.1">
         <source>The page alias is a unique reference to the page which can be called instead of its numeric ID.</source>
       </trans-unit>
+      <trans-unit id="tl_page.alias.0">
+        <source>URL parameters</source>
+      </trans-unit>
+      <trans-unit id="tl_page.alias.1">
+        <source>URL parameters are placeholders for the current reader page item, e.g. a news alias. Refer to the current page type for available parameters.</source>
+      </trans-unit>
       <trans-unit id="tl_page.type.0">
         <source>Page type</source>
       </trans-unit>

core-bundle/tests/Event/FilterPageTypeEventTest.php

@@ -0,0 +1,93 @@
+<?php
+
+namespace Contao\CoreBundle\Tests\Event;
+
+use Contao\CoreBundle\Event\FilterPageTypeEvent;
+use Contao\DataContainer;
+use PHPUnit\Framework\TestCase;
+
+class FilterPageTypeEventTest extends TestCase
+{
+    public function testReturnsDataContainer(): void
+    {
+        $dc = $this->createMock(DataContainer::class);
+
+        $event = new FilterPageTypeEvent([], $dc);
+
+        $this->assertSame($dc, $event->getDataContainer());
+    }
+
+    public function testReturnsOptionsWithNumericKeys(): void
+    {
+        $dc = $this->createMock(DataContainer::class);
+
+        $event = new FilterPageTypeEvent(['foo' => 'bar'], $dc);
+
+        $this->assertSame(['bar'], $event->getOptions());
+    }
+
+    public function testCanAddOption(): void
+    {
+        $dc = $this->createMock(DataContainer::class);
+
+        $event = new FilterPageTypeEvent([], $dc);
+
+        $this->assertSame([], $event->getOptions());
+
+        $event->addOption('foo');
+
+        $this->assertSame(['foo'], $event->getOptions());
+    }
+
+    public function testDoesNotAddDuplicateOptions(): void
+    {
+        $dc = $this->createMock(DataContainer::class);
+
+        $event = new FilterPageTypeEvent(['foo'], $dc);
+
+        $this->assertSame(['foo'], $event->getOptions());
+
+        $event->addOption('foo');
+
+        $this->assertSame(['foo'], $event->getOptions());
+    }
+
+    public function testCanSetOptions(): void
+    {
+        $dc = $this->createMock(DataContainer::class);
+
+        $event = new FilterPageTypeEvent(['foo'], $dc);
+
+        $this->assertSame(['foo'], $event->getOptions());
+
+        $event->setOptions(['foo' => 'bar']);
+
+        $this->assertSame(['bar'], $event->getOptions());
+    }
+
+    public function testCanRemoveOption(): void
+    {
+        $dc = $this->createMock(DataContainer::class);
+
+        $event = new FilterPageTypeEvent(['foo'], $dc);
+
+        $this->assertSame(['foo'], $event->getOptions());
+
+        $event->removeOption('foo');
+
+        $this->assertSame([], $event->getOptions());
+    }
+
+    public function testIgnoresMissingWhenRemovingOptions(): void
+    {
+        $dc = $this->createMock(DataContainer::class);
+
+        $event = new FilterPageTypeEvent(['foo'], $dc);
+
+        $this->assertSame(['foo'], $event->getOptions());
+
+        $event->removeOption('bar');
+
+        $this->assertSame(['foo'], $event->getOptions());
+    }
+}