Pass on previous exception in FatalThrowableError

This PR was squashed before being merged into the 2.7 branch (closes #25653).

Discussion
----------

PHP CS Fixer: clean up repo and adjust config

| Q             | A
| ------------- | ---
| Branch?       | 2.7
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | n/a
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

Reason for this PR is that one want to have `php-cs-fixer fix -v` command executed without changes that shall not be applied for this repo. To achieve that, we need to groom config to exclude files that violate CS willingly, fix files that are violating CS unwillingly, and deliver missing case handling at PHP CS Fixer itself (https://github.com/FriendsOfPHP/PHP-CS-Fixer/pull/3359) (already merged!).

Commits
-------

b14cbc1 PHP CS Fixer: clean up repo and adjust config

DebugClassLoader.php

@@ -142,7 +142,7 @@ class DebugClassLoader
      */
     public function findFile($class)
     {
-        @trigger_error('The '.__METHOD__.' method is deprecated since version 2.5 and will be removed in 3.0.', E_USER_DEPRECATED);
+        @trigger_error('The '.__METHOD__.' method is deprecated since Symfony 2.5 and will be removed in 3.0.', E_USER_DEPRECATED);
 
         if ($this->wasFinder) {
             return $this->classLoader[0]->findFile($class);
@@ -203,18 +203,11 @@ class DebugClassLoader
             } elseif (preg_match('#\n \* @deprecated (.*?)\r?\n \*(?: @|/$)#s', $refl->getDocComment(), $notice)) {
                 self::$deprecated[$name] = preg_replace('#\s*\r?\n \* +#', ' ', $notice[1]);
             } else {
-                if (2 > $len = 1 + (strpos($name, '\\', 1 + strpos($name, '\\')) ?: strpos($name, '_'))) {
+                if (2 > $len = 1 + (strpos($name, '\\') ?: strpos($name, '_'))) {
                     $len = 0;
                     $ns = '';
                 } else {
-                    switch ($ns = substr($name, 0, $len)) {
-                        case 'Symfony\Bridge\\':
-                        case 'Symfony\Bundle\\':
-                        case 'Symfony\Component\\':
-                            $ns = 'Symfony\\';
-                            $len = strlen($ns);
-                            break;
-                    }
+                    $ns = substr($name, 0, $len);
                 }
                 $parent = get_parent_class($class);
 

ErrorHandler.php

@@ -147,10 +147,24 @@ class ErrorHandler
             $handler = $prev[0];
             $replace = false;
         }
-        if ($replace || !$prev) {
-            $handler->setExceptionHandler(set_exception_handler(array($handler, 'handleException')));
-        } else {
+        if (!$replace && $prev) {
             restore_error_handler();
+            $handlerIsRegistered = is_array($prev) && $handler === $prev[0];
+        } else {
+            $handlerIsRegistered = true;
+        }
+        if (is_array($prev = set_exception_handler(array($handler, 'handleException'))) && $prev[0] instanceof self) {
+            restore_exception_handler();
+            if (!$handlerIsRegistered) {
+                $handler = $prev[0];
+            } elseif ($handler !== $prev[0] && $replace) {
+                set_exception_handler(array($handler, 'handleException'));
+                $p = $prev[0]->setExceptionHandler(null);
+                $handler->setExceptionHandler($p);
+                $prev[0]->setExceptionHandler($p);
+            }
+        } else {
+            $handler->setExceptionHandler($prev);
         }
 
         $handler->throwAt($levels & $handler->thrownErrors, true);
@@ -485,6 +499,7 @@ class ErrorHandler
             $exception = new FatalThrowableError($exception);
         }
         $type = $exception instanceof FatalErrorException ? $exception->getSeverity() : E_ERROR;
+        $handlerException = null;
 
         if (($this->loggedErrors & $type) || $exception instanceof FatalThrowableError) {
             $e = array(
@@ -529,18 +544,20 @@ class ErrorHandler
                 }
             }
         }
-        if (empty($this->exceptionHandler)) {
-            throw $exception; // Give back $exception to the native handler
-        }
         try {
-            call_user_func($this->exceptionHandler, $exception);
+            if (null !== $this->exceptionHandler) {
+                return \call_user_func($this->exceptionHandler, $exception);
+            }
+            $handlerException = $handlerException ?: $exception;
         } catch (\Exception $handlerException) {
         } catch (\Throwable $handlerException) {
         }
-        if (isset($handlerException)) {
-            $this->exceptionHandler = null;
-            $this->handleException($handlerException);
+        $this->exceptionHandler = null;
+        if ($exception === $handlerException) {
+            self::$reservedMemory = null; // Disable the fatal error handler
+            throw $exception; // Give back $exception to the native handler
         }
+        $this->handleException($handlerException);
     }
 
     /**
@@ -556,15 +573,39 @@ class ErrorHandler
             return;
         }
 
-        self::$reservedMemory = null;
+        $handler = self::$reservedMemory = null;
+        $handlers = array();
+        $previousHandler = null;
+        $sameHandlerLimit = 10;
 
-        $handler = set_error_handler('var_dump');
-        $handler = is_array($handler) ? $handler[0] : null;
-        restore_error_handler();
+        while (!is_array($handler) || !$handler[0] instanceof self) {
+            $handler = set_exception_handler('var_dump');
+            restore_exception_handler();
 
-        if (!$handler instanceof self) {
+            if (!$handler) {
+                break;
+            }
+            restore_exception_handler();
+
+            if ($handler !== $previousHandler) {
+                array_unshift($handlers, $handler);
+                $previousHandler = $handler;
+            } elseif (0 === --$sameHandlerLimit) {
+                $handler = null;
+                break;
+            }
+        }
+        foreach ($handlers as $h) {
+            set_exception_handler($h);
+        }
+        if (!$handler) {
             return;
         }
+        if ($handler !== $h) {
+            $handler[0]->setExceptionHandler($h);
+        }
+        $handler = $handler[0];
+        $handlers = array();
 
         if ($exit = null === $error) {
             $error = error_get_last();
@@ -673,7 +714,7 @@ class ErrorHandler
      */
     public function setLevel($level)
     {
-        @trigger_error('The '.__METHOD__.' method is deprecated since version 2.6 and will be removed in 3.0. Use the throwAt() method instead.', E_USER_DEPRECATED);
+        @trigger_error('The '.__METHOD__.' method is deprecated since Symfony 2.6 and will be removed in 3.0. Use the throwAt() method instead.', E_USER_DEPRECATED);
 
         $level = null === $level ? error_reporting() : $level;
         $this->throwAt($level, true);
@@ -688,7 +729,7 @@ class ErrorHandler
      */
     public function setDisplayErrors($displayErrors)
     {
-        @trigger_error('The '.__METHOD__.' method is deprecated since version 2.6 and will be removed in 3.0. Use the throwAt() method instead.', E_USER_DEPRECATED);
+        @trigger_error('The '.__METHOD__.' method is deprecated since Symfony 2.6 and will be removed in 3.0. Use the throwAt() method instead.', E_USER_DEPRECATED);
 
         if ($displayErrors) {
             $this->throwAt($this->displayErrors, true);
@@ -709,7 +750,7 @@ class ErrorHandler
      */
     public static function setLogger(LoggerInterface $logger, $channel = 'deprecation')
     {
-        @trigger_error('The '.__METHOD__.' static method is deprecated since version 2.6 and will be removed in 3.0. Use the setLoggers() or setDefaultLogger() methods instead.', E_USER_DEPRECATED);
+        @trigger_error('The '.__METHOD__.' static method is deprecated since Symfony 2.6 and will be removed in 3.0. Use the setLoggers() or setDefaultLogger() methods instead.', E_USER_DEPRECATED);
 
         $handler = set_error_handler('var_dump');
         $handler = is_array($handler) ? $handler[0] : null;
@@ -734,7 +775,7 @@ class ErrorHandler
      */
     public function handle($level, $message, $file = 'unknown', $line = 0, $context = array())
     {
-        $this->handleError(E_USER_DEPRECATED, 'The '.__METHOD__.' method is deprecated since version 2.6 and will be removed in 3.0. Use the handleError() method instead.', __FILE__, __LINE__, array());
+        $this->handleError(E_USER_DEPRECATED, 'The '.__METHOD__.' method is deprecated since Symfony 2.6 and will be removed in 3.0. Use the handleError() method instead.', __FILE__, __LINE__, array());
 
         return $this->handleError($level, $message, $file, $line, (array) $context);
     }
@@ -746,7 +787,7 @@ class ErrorHandler
      */
     public function handleFatal()
     {
-        @trigger_error('The '.__METHOD__.' method is deprecated since version 2.6 and will be removed in 3.0. Use the handleFatalError() method instead.', E_USER_DEPRECATED);
+        @trigger_error('The '.__METHOD__.' method is deprecated since Symfony 2.6 and will be removed in 3.0. Use the handleFatalError() method instead.', E_USER_DEPRECATED);
 
         static::handleFatalError();
     }

Exception/DummyException.php

@@ -11,7 +11,7 @@
 
 namespace Symfony\Component\Debug\Exception;
 
-@trigger_error('The '.__NAMESPACE__.'\DummyException class is deprecated since version 2.5 and will be removed in 3.0.', E_USER_DEPRECATED);
+@trigger_error('The '.__NAMESPACE__.'\DummyException class is deprecated since Symfony 2.5 and will be removed in 3.0.', E_USER_DEPRECATED);
 
 /**
  * @author Fabien Potencier <fabien@symfony.com>

Exception/FatalThrowableError.php

@@ -36,7 +36,8 @@ class FatalThrowableError extends FatalErrorException
             $e->getCode(),
             $severity,
             $e->getFile(),
-            $e->getLine()
+            $e->getLine(),
+            $e->getPrevious()
         );
 
         $this->setTrace($e->getTrace());

ExceptionHandler.php

@@ -151,8 +151,6 @@ class ExceptionHandler
      * If you have the Symfony HttpFoundation component installed,
      * this method will use it to create and send the response. If not,
      * it will fallback to plain PHP functions.
-     *
-     * @param \Exception $exception An \Exception instance
      */
     private function failSafeHandle(\Exception $exception)
     {
@@ -215,8 +213,6 @@ class ExceptionHandler
     /**
      * Gets the HTML content associated with the given exception.
      *
-     * @param FlattenException $exception A FlattenException instance
-     *
      * @return string The content as a string
      */
     public function getContent(FlattenException $exception)
@@ -283,8 +279,6 @@ EOF;
     /**
      * Gets the stylesheet associated with the given exception.
      *
-     * @param FlattenException $exception A FlattenException instance
-     *
      * @return string The stylesheet as a string
      */
     public function getStylesheet(FlattenException $exception)
@@ -432,7 +426,7 @@ EOF;
      */
     protected static function utf8Htmlize($str)
     {
-        @trigger_error('The '.__METHOD__.' method is deprecated since version 2.7 and will be removed in 3.0.', E_USER_DEPRECATED);
+        @trigger_error('The '.__METHOD__.' method is deprecated since Symfony 2.7 and will be removed in 3.0.', E_USER_DEPRECATED);
 
         return htmlspecialchars($str, ENT_QUOTES | (\PHP_VERSION_ID >= 50400 ? ENT_SUBSTITUTE : 0), 'UTF-8');
     }

LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2004-2017 Fabien Potencier
+Copyright (c) 2004-2018 Fabien Potencier
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

Resources/ext/tests/001.phpt

@@ -1,7 +1,9 @@
 --TEST--
 Test symfony_zval_info API
 --SKIPIF--
-<?php if (!extension_loaded('symfony_debug')) print 'skip'; ?>
+<?php if (!extension_loaded('symfony_debug')) {
+    echo 'skip';
+} ?>
 --FILE--
 <?php
 

Resources/ext/tests/002.phpt

@@ -1,7 +1,9 @@
 --TEST--
 Test symfony_debug_backtrace in case of fatal error
 --SKIPIF--
-<?php if (!extension_loaded('symfony_debug')) print 'skip'; ?>
+<?php if (!extension_loaded('symfony_debug')) {
+    echo 'skip';
+} ?>
 --FILE--
 <?php
 

Resources/ext/tests/002_1.phpt

@@ -1,7 +1,9 @@
 --TEST--
 Test symfony_debug_backtrace in case of non fatal error
 --SKIPIF--
-<?php if (!extension_loaded('symfony_debug')) print 'skip'; ?>
+<?php if (!extension_loaded('symfony_debug')) {
+    echo 'skip';
+} ?>
 --FILE--
 <?php
 

Resources/ext/tests/003.phpt

@@ -1,7 +1,9 @@
 --TEST--
 Test ErrorHandler in case of fatal error
 --SKIPIF--
-<?php if (!extension_loaded('symfony_debug')) print 'skip'; ?>
+<?php if (!extension_loaded('symfony_debug')) {
+    echo 'skip';
+} ?>
 --FILE--
 <?php
 

Tests/ErrorHandlerTest.php

@@ -34,7 +34,7 @@ class ErrorHandlerTest extends TestCase
 
             $newHandler = new ErrorHandler();
 
-            $this->assertSame($newHandler, ErrorHandler::register($newHandler, false));
+            $this->assertSame($handler, ErrorHandler::register($newHandler, false));
             $h = set_error_handler('var_dump');
             restore_error_handler();
             $this->assertSame(array($handler, 'handleError'), $h);
@@ -79,7 +79,9 @@ class ErrorHandlerTest extends TestCase
             $this->assertEquals(E_NOTICE, $exception->getSeverity());
             $this->assertEquals(__FILE__, $exception->getFile());
             $this->assertRegExp('/^Notice: Undefined variable: (foo|bar)/', $exception->getMessage());
-            $this->assertArrayHasKey('foobar', $exception->getContext());
+            if (\PHP_VERSION_ID < 70200) {
+                $this->assertArrayHasKey('foobar', $exception->getContext());
+            }
 
             $trace = $exception->getTrace();
             $this->assertEquals(__FILE__, $trace[0]['file']);
@@ -291,6 +293,9 @@ class ErrorHandlerTest extends TestCase
         @$handler->handleError(E_USER_DEPRECATED, 'Foo deprecation', __FILE__, __LINE__, array());
     }
 
+    /**
+     * @group no-hhvm
+     */
     public function testHandleException()
     {
         try {
@@ -373,6 +378,9 @@ class ErrorHandlerTest extends TestCase
         }
     }
 
+    /**
+     * @group no-hhvm
+     */
     public function testHandleFatalError()
     {
         try {
@@ -432,6 +440,9 @@ class ErrorHandlerTest extends TestCase
         $this->assertStringStartsWith("Attempted to load class \"Foo\" from the global namespace.\nDid you forget a \"use\" statement", $args[0]->getMessage());
     }
 
+    /**
+     * @group no-hhvm
+     */
     public function testHandleFatalErrorOnHHVM()
     {
         try {

Tests/Exception/FlattenExceptionTest.php

@@ -105,7 +105,7 @@ class FlattenExceptionTest extends TestCase
     /**
      * @dataProvider flattenDataProvider
      */
-    public function testFlattenHttpException(\Exception $exception, $statusCode)
+    public function testFlattenHttpException(\Exception $exception)
     {
         $flattened = FlattenException::create($exception);
         $flattened2 = FlattenException::create($exception);
@@ -120,7 +120,7 @@ class FlattenExceptionTest extends TestCase
     /**
      * @dataProvider flattenDataProvider
      */
-    public function testPrevious(\Exception $exception, $statusCode)
+    public function testPrevious(\Exception $exception)
     {
         $flattened = FlattenException::create($exception);
         $flattened2 = FlattenException::create($exception);
@@ -167,7 +167,7 @@ class FlattenExceptionTest extends TestCase
     /**
      * @dataProvider flattenDataProvider
      */
-    public function testToArray(\Exception $exception, $statusCode)
+    public function testToArray(\Exception $exception)
     {
         $flattened = FlattenException::create($exception);
         $flattened->setTrace(array(), 'foo.php', 123);
@@ -187,12 +187,13 @@ class FlattenExceptionTest extends TestCase
     public function flattenDataProvider()
     {
         return array(
-            array(new \Exception('test', 123), 500),
+            array(new \Exception('test', 123)),
         );
     }
 
     public function testRecursionInArguments()
     {
+        $a = null;
         $a = array('foo', array(2, &$a));
         $exception = $this->createException($a);
 

Tests/phpt/decorate_exception_hander.phpt

@@ -0,0 +1,47 @@
+--TEST--
+Test catching fatal errors when handlers are nested
+--FILE--
+<?php
+
+namespace Symfony\Component\Debug;
+
+$vendor = __DIR__;
+while (!file_exists($vendor.'/vendor')) {
+    $vendor = dirname($vendor);
+}
+require $vendor.'/vendor/autoload.php';
+
+set_error_handler('var_dump');
+set_exception_handler('var_dump');
+
+ErrorHandler::register(null, false);
+
+if (true) {
+    class foo extends missing
+    {
+    }
+}
+
+?>
+--EXPECTF--
+Fatal error: Class 'Symfony\Component\Debug\missing' not found in %s on line %d
+object(Symfony\Component\Debug\Exception\ClassNotFoundException)#%d (8) {
+  ["message":protected]=>
+  string(131) "Attempted to load class "missing" from namespace "Symfony\Component\Debug".
+Did you forget a "use" statement for another namespace?"
+  ["string":"Exception":private]=>
+  string(0) ""
+  ["code":protected]=>
+  int(0)
+  ["file":protected]=>
+  string(%d) "%s"
+  ["line":protected]=>
+  int(%d)
+  ["trace":"Exception":private]=>
+  array(0) {
+  }
+  ["previous":"Exception":private]=>
+  NULL
+  ["severity":protected]=>
+  int(1)
+}

Tests/phpt/exception_rethrown.phpt

@@ -0,0 +1,35 @@
+--TEST--
+Test rethrowing in custom exception handler
+--FILE--
+<?php
+
+namespace Symfony\Component\Debug;
+
+$vendor = __DIR__;
+while (!file_exists($vendor.'/vendor')) {
+    $vendor = dirname($vendor);
+}
+require $vendor.'/vendor/autoload.php';
+
+if (true) {
+    class TestLogger extends \Psr\Log\AbstractLogger
+    {
+        public function log($level, $message, array $context = array())
+        {
+            echo $message, "\n";
+        }
+    }
+}
+
+set_exception_handler(function ($e) { echo 123; throw $e; });
+ErrorHandler::register()->setDefaultLogger(new TestLogger());
+ini_set('display_errors', 1);
+
+throw new \Exception('foo');
+?>
+--EXPECTF--
+Uncaught Exception: foo
+123
+Fatal error: Uncaught %s:25
+Stack trace:
+%a

Tests/phpt/fatal_with_nested_handlers.phpt

@@ -0,0 +1,42 @@
+--TEST--
+Test catching fatal errors when handlers are nested
+--FILE--
+<?php
+
+namespace Symfony\Component\Debug;
+
+$vendor = __DIR__;
+while (!file_exists($vendor.'/vendor')) {
+    $vendor = dirname($vendor);
+}
+require $vendor.'/vendor/autoload.php';
+
+Debug::enable();
+ini_set('display_errors', 0);
+
+$eHandler = set_error_handler('var_dump');
+$xHandler = set_exception_handler('var_dump');
+
+var_dump(array(
+    $eHandler[0] === $xHandler[0] ? 'Error and exception handlers do match' : 'Error and exception handlers are different',
+));
+
+$eHandler[0]->setExceptionHandler('print_r');
+
+if (true) {
+    class Broken implements \Serializable
+    {
+    }
+}
+
+?>
+--EXPECTF--
+array(1) {
+  [0]=>
+  string(37) "Error and exception handlers do match"
+}
+object(Symfony\Component\Debug\Exception\FatalErrorException)#%d (8) {
+  ["message":protected]=>
+  string(199) "Error: Class Symfony\Component\Debug\Broken contains 2 abstract methods and must therefore be declared abstract or implement the remaining methods (Serializable::serialize, Serializable::unserialize)"
+%a
+}