[8.x] Support union types on event discovery

src/Illuminate/Foundation/Events/DiscoverEvents.php

@@ -21,11 +21,23 @@ class DiscoverEvents
      */
     public static function within($listenerPath, $basePath)
     {
-        return collect(static::getListenerEvents(
+        $listeners = collect(static::getListenerEvents(
             (new Finder)->files()->in($listenerPath), $basePath
-        ))->mapToDictionary(function ($event, $listener) {
-            return [$event => $listener];
-        })->all();
+        ));
+
+        $discoveredEvents = [];
+
+        foreach ($listeners as $listener => $events) {
+            foreach ($events as $event) {
+                if (! isset($discoveredEvents[$event])) {
+                    $discoveredEvents[$event] = [];
+                }
+
+                $discoveredEvents[$event][] = $listener;
+            }
+        }
+
+        return $discoveredEvents;
     }
 
     /**
@@ -59,7 +71,7 @@ protected static function getListenerEvents($listeners, $basePath)
                 }
 
                 $listenerEvents[$listener->name.'@'.$method->name] =
-                                Reflector::getParameterClassName($method->getParameters()[0]);
+                                Reflector::getParameterClassNames($method->getParameters()[0]);
             }
         }
 

src/Illuminate/Support/Reflector.php

@@ -5,6 +5,7 @@
 use ReflectionClass;
 use ReflectionMethod;
 use ReflectionNamedType;
+use ReflectionUnionType;
 
 class Reflector
 {
@@ -69,6 +70,45 @@ public static function getParameterClassName($parameter)
             return;
         }
 
+        return static::getTypeName($parameter, $type);
+    }
+
+    /**
+     * Get the class names of the given parameter's type, including union types.
+     *
+     * @param  \ReflectionParameter  $parameter
+     * @return array
+     */
+    public static function getParameterClassNames($parameter)
+    {
+        $type = $parameter->getType();
+
+        if (! $type instanceof ReflectionUnionType) {
+            return [static::getParameterClassName($parameter)];
+        }
+
+        $unionTypes = [];
+
+        foreach ($type->getTypes() as $listedType) {
+            if (! $listedType instanceof ReflectionNamedType || $listedType->isBuiltin()) {
+                continue;
+            }
+
+            $unionTypes[] = static::getTypeName($parameter, $listedType);
+        }
+
+        return $unionTypes;
+    }
+
+    /**
+     * Get the given type's class name.
+     *
+     * @param  \ReflectionParameter  $parameter
+     * @param  \ReflectionNamedType  $type
+     * @return string
+     */
+    protected static function getTypeName($parameter, $type)
+    {
         $name = $type->getName();
 
         if (! is_null($class = $parameter->getDeclaringClass())) {

tests/Integration/Foundation/DiscoverEventsTest.php

@@ -8,6 +8,7 @@
 use Illuminate\Tests\Integration\Foundation\Fixtures\EventDiscovery\Listeners\AbstractListener;
 use Illuminate\Tests\Integration\Foundation\Fixtures\EventDiscovery\Listeners\Listener;
 use Illuminate\Tests\Integration\Foundation\Fixtures\EventDiscovery\Listeners\ListenerInterface;
+use Illuminate\Tests\Integration\Foundation\Fixtures\EventDiscovery\UnionListeners\UnionListener;
 use Orchestra\Testbench\TestCase;
 
 class DiscoverEventsTest extends TestCase
@@ -30,4 +31,24 @@ class_alias(ListenerInterface::class, 'Tests\Integration\Foundation\Fixtures\Eve
             ],
         ], $events);
     }
+
+    public function testUnionEventsCanBeDiscovered()
+    {
+        if (version_compare(phpversion(), '8.0.0', '<')) {
+            $this->markTestSkipped('Test uses union types.');
+        }
+
+        class_alias(UnionListener::class, 'Tests\Integration\Foundation\Fixtures\EventDiscovery\UnionListeners\UnionListener');
+
+        $events = DiscoverEvents::within(__DIR__.'/Fixtures/EventDiscovery/UnionListeners', getcwd());
+
+        $this->assertEquals([
+            EventOne::class => [
+                UnionListener::class.'@handle',
+            ],
+            EventTwo::class => [
+                UnionListener::class.'@handle',
+            ],
+        ], $events);
+    }
 }

tests/Integration/Foundation/Fixtures/EventDiscovery/UnionListeners/UnionListener.php

@@ -0,0 +1,14 @@
+<?php
+
+namespace Illuminate\Tests\Integration\Foundation\Fixtures\EventDiscovery\UnionListeners;
+
+use Illuminate\Tests\Integration\Foundation\Fixtures\EventDiscovery\Events\EventOne;
+use Illuminate\Tests\Integration\Foundation\Fixtures\EventDiscovery\Events\EventTwo;
+
+class UnionListener
+{
+    public function handle(EventOne|EventTwo $event)
+    {
+        //
+    }
+}