[11.x] Fix issue where $name variable in non base config file becomes it's key (#52738)

* Prepare example where the `$name` variable becomes the key of the config

* Require path in isolation

* Use arrow function

Author: rojtjo

src/Illuminate/Foundation/Bootstrap/LoadConfiguration.php

@@ -93,7 +93,7 @@ protected function loadConfigurationFiles(Application $app, RepositoryContract $
      */
     protected function loadConfigurationFile(RepositoryContract $repository, $name, $path, array $base)
     {
-        $config = require $path;
+        $config = (fn () => require $path)();
 
         if (isset($base[$name])) {
             $config = array_merge($base[$name], $config);

tests/Foundation/Bootstrap/LoadConfigurationTest.php

@@ -26,4 +26,15 @@ public function testDontLoadBaseConfiguration()
 
         $this->assertNull($app['config']['app.name']);
     }
+
+    public function testLoadsConfigurationInIsolation()
+    {
+        $app = new Application(__DIR__.'/../fixtures');
+        $app->useConfigPath(__DIR__.'/../fixtures/config');
+
+        (new LoadConfiguration())->bootstrap($app);
+
+        $this->assertNull($app['config']['bar.foo']);
+        $this->assertSame('bar', $app['config']['custom.foo']);
+    }
 }

tests/Foundation/fixtures/config/custom.php

@@ -0,0 +1,7 @@
+<?php
+
+$name = 'bar';
+
+return [
+    'foo' => $name,
+];