[Debug] Tell that the extension is for PHP 5 only

```
php > echo (E_ALL | E_STRICT) & (0 | E_RECOVERABLE_ERROR | E_USER_ERROR) & ~E_USER_DEPRECATED & ~E_DEPRECATED;
4352
php > echo (0 | E_RECOVERABLE_ERROR | E_USER_ERROR) & ~E_USER_DEPRECATED & ~E_DEPRECATED;
4352
php > echo (2 | E_RECOVERABLE_ERROR | E_USER_ERROR) & ~E_USER_DEPRECATED & ~E_DEPRECATED;
4354
```

DebugClassLoader.php

@@ -224,7 +224,7 @@ class DebugClassLoader
                 $i = count($tail) - 1;
                 $j = count($real) - 1;
 
-                 while (isset($tail[$i], $real[$j]) && $tail[$i] === $real[$j]) {
+                while (isset($tail[$i], $real[$j]) && $tail[$i] === $real[$j]) {
                     --$i;
                     --$j;
                 }

ErrorHandler.php

@@ -257,7 +257,7 @@ class ErrorHandler
     public function throwAt($levels, $replace = false)
     {
         $prev = $this->thrownErrors;
-        $this->thrownErrors = (E_ALL | E_STRICT) & ($levels | E_RECOVERABLE_ERROR | E_USER_ERROR) & ~E_USER_DEPRECATED & ~E_DEPRECATED;
+        $this->thrownErrors = ($levels | E_RECOVERABLE_ERROR | E_USER_ERROR) & ~E_USER_DEPRECATED & ~E_DEPRECATED;
         if (!$replace) {
             $this->thrownErrors |= $prev;
         }

Resources/ext/README.md

@@ -1,7 +1,9 @@
-Symfony Debug Extension
-=======================
+Symfony Debug Extension for PHP 5
+=================================
 
 This extension publishes several functions to help building powerful debugging tools.
+It is compatible with PHP 5.3, 5.4, 5.5 and 5.6; with ZTS and non-ZTS modes.
+It is not required thus not provided for PHP 7.
 
 symfony_zval_info()
 -------------------
@@ -122,7 +124,6 @@ array(3) {
 Usage
 -----
 
-The extension is compatible with ZTS mode, and should be supported by PHP5.3, 5.4, 5.5 and 5.6.
 To enable the extension from source, run:
 
 ```

Tests/DebugClassLoaderTest.php

@@ -175,7 +175,7 @@ class DebugClassLoaderTest extends \PHPUnit_Framework_TestCase
      */
     public function testDeprecatedSuper($class, $super, $type)
     {
-        set_error_handler(function() { return false; });
+        set_error_handler(function () { return false; });
         $e = error_reporting(0);
         trigger_error('', E_USER_DEPRECATED);
 
@@ -205,7 +205,7 @@ class DebugClassLoaderTest extends \PHPUnit_Framework_TestCase
 
     public function testDeprecatedSuperInSameNamespace()
     {
-        set_error_handler(function() { return false; });
+        set_error_handler(function () { return false; });
         $e = error_reporting(0);
         trigger_error('', E_USER_NOTICE);
 
@@ -231,7 +231,7 @@ class DebugClassLoaderTest extends \PHPUnit_Framework_TestCase
             $this->markTestSkipped('PHP7 already prevents using reserved names.');
         }
 
-        set_error_handler(function() { return false; });
+        set_error_handler(function () { return false; });
         $e = error_reporting(0);
         trigger_error('', E_USER_NOTICE);