Fixes #3542: Removed requirement to specify `extensions` in application config

apps/advanced/common/config/main.php

 <?php
 return [
     'vendorPath' => dirname(dirname(__DIR__)) . '/vendor',
-    'extensions' => require(__DIR__ . '/../../vendor/yiisoft/extensions.php'),
     'components' => [
         'cache' => [
             'class' => 'yii\caching\FileCache',

apps/basic/config/console.php

@@ -10,7 +10,6 @@ return [
     'basePath' => dirname(__DIR__),
     'bootstrap' => ['log'],
     'controllerNamespace' => 'app\commands',
-    'extensions' => require(__DIR__ . '/../vendor/yiisoft/extensions.php'),
     'components' => [
         'cache' => [
             'class' => 'yii\caching\FileCache',

apps/basic/config/web.php

@@ -6,7 +6,6 @@ $config = [
     'id' => 'basic',
     'basePath' => dirname(__DIR__),
     'bootstrap' => ['log'],
-    'extensions' => require(__DIR__ . '/../vendor/yiisoft/extensions.php'),
     'components' => [
         'cache' => [
             'class' => 'yii\caching\FileCache',

framework/CHANGELOG.md

@@ -54,6 +54,7 @@ Yii Framework 2 Change Log
 - Enh #3472: Added configurable option to encode spaces in dropDownLists and listBoxes (kartik-v)
 - Enh #3518: `yii\helpers\Html::encode()` now replaces invalid code sequences with "?" (DaSourcerer)
 - Enh #3521: Added `yii\filters\HttpCache::sessionCacheLimiter` (qiangxue)
+- Enh #3542: Removed requirement to specify `extensions` in application config (samdark)
 - Enh: Added support for using sub-queries when building a DB query with `IN` condition (qiangxue)
 - Enh: Supported adding a new response formatter without the need to reconfigure existing formatters (qiangxue)
 - Enh: Added `yii\web\UrlManager::addRules()` to simplify adding new URL rules (qiangxue)

framework/base/Application.php

@@ -8,6 +8,7 @@
 namespace yii\base;
 
 use Yii;
+use yii\log\Logger;
 
 /**
  * Application is the base class for all application classes.
@@ -151,8 +152,11 @@ abstract class Application extends Module
      * The "bootstrap" class listed above will be instantiated during the application
      * [[bootstrap()|bootstrapping process]]. If the class implements [[BootstrapInterface]],
      * its [[BootstrapInterface::bootstrap()|bootstrap()]] method will be also be called.
+     *
+     * If the property isn't specified in the application bootstrap file i.e. index.php, content is loaded automatically
+     * from @vendor/yiisoft/extensions.php.
      */
-    public $extensions = [];
+    public $extensions;
     /**
      * @var array list of components that should be run during the application [[bootstrap()|bootstrapping process]].
      *
@@ -262,6 +266,13 @@ abstract class Application extends Module
      */
     protected function bootstrap()
     {
+        if ($this->extensions === null) {
+            try {
+                $this->extensions = include Yii::getAlias('@vendor/yiisoft/extensions.php');
+            } catch (ErrorException $e) {
+                $this->extensions = [];
+            }
+        }
         foreach ($this->extensions as $extension) {
             if (!empty($extension['alias'])) {
                 foreach ($extension['alias'] as $name => $path) {