[ErrorHandler][Debug] Do not use the php80 polyfill

Leverage str_contains/str_starts_with
Signed-off-by: Alexander M. Turek <me@derrabus.de>
2026-03-25 17:52:07 +01:00 · 2021-07-22 09:21:39 +02:00 · 2021-07-21 14:19:41 +02:00 · 2021-07-21 13:57:04 +02:00 · 2021-07-18 16:08:08 +02:00 · 2021-05-26 19:39:37 +02:00
38 changed files with 683 additions and 471 deletions
--- a/.gitattributes
+++ b/.gitattributes
@@ -0,0 +1,4 @@
+/Tests export-ignore
+/phpunit.xml.dist export-ignore
+/.gitattributes export-ignore
+/.gitignore export-ignore
--- a/BufferingLogger.php
+++ b/BufferingLogger.php
@@ -13,15 +13,22 @@ namespace Symfony\Component\Debug;

 use Psr\Log\AbstractLogger;

+@trigger_error(sprintf('The "%s" class is deprecated since Symfony 4.4, use "%s" instead.', BufferingLogger::class, \Symfony\Component\ErrorHandler\BufferingLogger::class), \E_USER_DEPRECATED);
+
 /**
 * A buffering logger that stacks logs for later.
 *
 * @author Nicolas Grekas <p@tchwork.com>
+ *
+ * @deprecated since Symfony 4.4, use Symfony\Component\ErrorHandler\BufferingLogger instead.
 */
 class BufferingLogger extends AbstractLogger
 {
    private $logs = [];

+    /**
+     * @return void
+     */
    public function log($level, $message, array $context = [])
    {
        $this->logs[] = [$level, $message, $context];
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,70 +1,75 @@
 CHANGELOG
 =========

+4.4.0
+-----
+
+ * deprecated `FlattenException`, use the `FlattenException` of the `ErrorHandler` component
+ * deprecated the whole component in favor of the `ErrorHandler` component
+
 4.3.0
 -----

-* made the `ErrorHandler` and `ExceptionHandler` classes final
-* added `Exception\FlattenException::getAsString` and
-`Exception\FlattenException::getTraceAsString` to increase compatibility to php
-exception objects
+ * made the `ErrorHandler` and `ExceptionHandler` classes final
+ * added `Exception\FlattenException::getAsString` and
+   `Exception\FlattenException::getTraceAsString` to increase compatibility to php
+   exception objects

 4.0.0
 -----

-* removed the symfony_debug extension
-* removed `ContextErrorException`
+ * removed the symfony_debug extension
+ * removed `ContextErrorException`

 3.4.0
 -----

-* deprecated `ErrorHandler::stackErrors()` and `ErrorHandler::unstackErrors()`
+ * deprecated `ErrorHandler::stackErrors()` and `ErrorHandler::unstackErrors()`

 3.3.0
 -----

-* deprecated the `ContextErrorException` class: use \ErrorException directly now
+ * deprecated the `ContextErrorException` class: use \ErrorException directly now

 3.2.0
 -----

-* `FlattenException::getTrace()` now returns additional type descriptions
-  `integer` and `float`.
-
+ * `FlattenException::getTrace()` now returns additional type descriptions
+   `integer` and `float`.

 3.0.0
 -----

-* removed classes, methods and interfaces deprecated in 2.x
+ * removed classes, methods and interfaces deprecated in 2.x

 2.8.0
 -----

-* added BufferingLogger for errors that happen before a proper logger is configured
-* allow throwing from `__toString()` with `return trigger_error($e, E_USER_ERROR);`
-* deprecate ExceptionHandler::createResponse
+ * added BufferingLogger for errors that happen before a proper logger is configured
+ * allow throwing from `__toString()` with `return trigger_error($e, E_USER_ERROR);`
+ * deprecate ExceptionHandler::createResponse

 2.7.0
 -----

-* added deprecations checking for parent interfaces/classes to DebugClassLoader
-* added ZTS support to symfony_debug extension
-* added symfony_debug_backtrace() to symfony_debug extension
-  to track the backtrace of fatal errors
+ * added deprecations checking for parent interfaces/classes to DebugClassLoader
+ * added ZTS support to symfony_debug extension
+ * added symfony_debug_backtrace() to symfony_debug extension
+   to track the backtrace of fatal errors

 2.6.0
 -----

-* generalized ErrorHandler and ExceptionHandler,
-  with some new methods and others deprecated
-* enhanced error messages for uncaught exceptions
+ * generalized ErrorHandler and ExceptionHandler,
+   with some new methods and others deprecated
+ * enhanced error messages for uncaught exceptions

 2.5.0
 -----

-* added ExceptionHandler::setHandler()
-* added UndefinedMethodFatalErrorHandler
-* deprecated DummyException
+ * added ExceptionHandler::setHandler()
+ * added UndefinedMethodFatalErrorHandler
+ * deprecated DummyException

 2.4.0
 -----
--- a/Debug.php
+++ b/Debug.php
@@ -11,10 +11,14 @@

 namespace Symfony\Component\Debug;

+@trigger_error(sprintf('The "%s" class is deprecated since Symfony 4.4, use "%s" instead.', Debug::class, \Symfony\Component\ErrorHandler\Debug::class), \E_USER_DEPRECATED);
+
 /**
 * Registers all the debug tools.
 *
 * @author Fabien Potencier <fabien@symfony.com>
+ *
+ * @deprecated since Symfony 4.4, use Symfony\Component\ErrorHandler\Debug instead.
 */
 class Debug
 {
@@ -28,7 +32,7 @@ class Debug
     * @param int  $errorReportingLevel The level of error reporting you want
     * @param bool $displayErrors       Whether to display errors (for development) or just log them (for production)
     */
-    public static function enable($errorReportingLevel = E_ALL, $displayErrors = true)
+    public static function enable($errorReportingLevel = \E_ALL, $displayErrors = true)
    {
        if (static::$enabled) {
            return;
@@ -39,13 +43,13 @@ class Debug
        if (null !== $errorReportingLevel) {
            error_reporting($errorReportingLevel);
        } else {
-            error_reporting(E_ALL);
+            error_reporting(\E_ALL);
        }

        if (!\in_array(\PHP_SAPI, ['cli', 'phpdbg'], true)) {
            ini_set('display_errors', 0);
            ExceptionHandler::register();
-        } elseif ($displayErrors && (!filter_var(ini_get('log_errors'), FILTER_VALIDATE_BOOLEAN) || ini_get('error_log'))) {
+        } elseif ($displayErrors && (!filter_var(ini_get('log_errors'), \FILTER_VALIDATE_BOOLEAN) || ini_get('error_log'))) {
            // CLI - display errors only if they're not already logged to STDERR
            ini_set('display_errors', 1);
        }
--- a/DebugClassLoader.php
+++ b/DebugClassLoader.php
@@ -13,6 +13,8 @@ namespace Symfony\Component\Debug;

 use PHPUnit\Framework\MockObject\Matcher\StatelessInvocation;

+@trigger_error(sprintf('The "%s" class is deprecated since Symfony 4.4, use "%s" instead.', DebugClassLoader::class, \Symfony\Component\ErrorHandler\DebugClassLoader::class), \E_USER_DEPRECATED);
+
 /**
 * Autoloader checking if the class is really defined in the file found.
 *
@@ -24,6 +26,8 @@ use PHPUnit\Framework\MockObject\Matcher\StatelessInvocation;
 * @author Christophe Coevoet <stof@notk.org>
 * @author Nicolas Grekas <p@tchwork.com>
 * @author Guilhem Niot <guilhem.niot@gmail.com>
+ *
+ * @deprecated since Symfony 4.4, use Symfony\Component\ErrorHandler\DebugClassLoader instead.
 */
 class DebugClassLoader
 {
@@ -60,7 +64,7 @@ class DebugClassLoader
            } elseif (substr($test, -\strlen($file)) === $file) {
                // filesystem is case insensitive and realpath() normalizes the case of characters
                self::$caseCheck = 1;
-            } elseif (false !== stripos(PHP_OS, 'darwin')) {
+            } elseif (false !== stripos(\PHP_OS, 'darwin')) {
                // on MacOSX, HFS+ is case insensitive but realpath() doesn't normalize the case of characters
                self::$caseCheck = 2;
            } else {
@@ -86,8 +90,8 @@ class DebugClassLoader
    public static function enable()
    {
        // Ensures we don't hit https://bugs.php.net/42098
-        class_exists('Symfony\Component\Debug\ErrorHandler');
-        class_exists('Psr\Log\LogLevel');
+        class_exists(\Symfony\Component\Debug\ErrorHandler::class);
+        class_exists(\Psr\Log\LogLevel::class);

        if (!\is_array($functions = spl_autoload_functions())) {
            return;
@@ -145,7 +149,7 @@ class DebugClassLoader
     */
    public function loadClass($class)
    {
-        $e = error_reporting(error_reporting() | E_PARSE | E_ERROR | E_CORE_ERROR | E_COMPILE_ERROR);
+        $e = error_reporting(error_reporting() | \E_PARSE | \E_ERROR | \E_CORE_ERROR | \E_COMPILE_ERROR);

        try {
            if ($this->isFinder && !isset($this->loaded[$class])) {
@@ -153,11 +157,11 @@ class DebugClassLoader
                if (!$file = $this->classLoader[0]->findFile($class) ?: false) {
                    // no-op
                } elseif (\function_exists('opcache_is_script_cached') && @opcache_is_script_cached($file)) {
-                    require $file;
+                    include $file;

                    return;
-                } else {
-                    require $file;
+                } elseif (false === include $file) {
+                    return;
                }
            } else {
                ($this->classLoader)($class);
@@ -170,7 +174,7 @@ class DebugClassLoader
        $this->checkClass($class, $file);
    }

-    private function checkClass($class, $file = null)
+    private function checkClass(string $class, string $file = null)
    {
        $exists = null === $file || class_exists($class, false) || interface_exists($class, false) || trait_exists($class, false);

@@ -197,7 +201,7 @@ class DebugClassLoader
            $deprecations = $this->checkAnnotations($refl, $name);

            foreach ($deprecations as $message) {
-                @trigger_error($message, E_USER_DEPRECATED);
+                @trigger_error($message, \E_USER_DEPRECATED);
            }
        }

@@ -238,7 +242,7 @@ class DebugClassLoader
                }
            }

-            if ($refl->isInterface() && false !== strpos($doc, 'method') && preg_match_all('#\n \* @method\s+(static\s+)?+(?:[\w\|&\[\]\\\]+\s+)?(\w+(?:\s*\([^\)]*\))?)+(.+?([[:punct:]]\s*)?)?(?=\r?\n \*(?: @|/$|\r?\n))#', $doc, $notice, PREG_SET_ORDER)) {
+            if ($refl->isInterface() && false !== strpos($doc, 'method') && preg_match_all('#\n \* @method\s+(static\s+)?+(?:[\w\|&\[\]\\\]+\s+)?(\w+(?:\s*\([^\)]*\))?)+(.+?([[:punct:]]\s*)?)?(?=\r?\n \*(?: @|/$|\r?\n))#', $doc, $notice, \PREG_SET_ORDER)) {
                foreach ($notice as $method) {
                    $static = '' !== $method[1];
                    $name = $method[2];
@@ -258,7 +262,7 @@ class DebugClassLoader
        }

        $parent = get_parent_class($class);
-        $parentAndOwnInterfaces = $this->getOwnInterfaces($class, $parent);
+        $parentAndOwnInterfaces = $this->getOwnInterfaces($class, $parent ?: null);
        if ($parent) {
            $parentAndOwnInterfaces[$parent] = $parent;

@@ -296,7 +300,7 @@ class DebugClassLoader
                    $hasCall = $refl->hasMethod('__call');
                    $hasStaticCall = $refl->hasMethod('__callStatic');
                    foreach (self::$method[$use] as $method) {
-                        list($interface, $name, $static, $description) = $method;
+                        [$interface, $name, $static, $description] = $method;
                        if ($static ? $hasStaticCall : $hasCall) {
                            continue;
                        }
@@ -331,12 +335,12 @@ class DebugClassLoader
            }

            if ($parent && isset(self::$finalMethods[$parent][$method->name])) {
-                list($declaringClass, $message) = self::$finalMethods[$parent][$method->name];
+                [$declaringClass, $message] = self::$finalMethods[$parent][$method->name];
                $deprecations[] = sprintf('The "%s::%s()" method is considered final%s. It may change without further notice as of its next major version. You should not extend it from "%s".', $declaringClass, $method->name, $message, $class);
            }

            if (isset(self::$internalMethods[$class][$method->name])) {
-                list($declaringClass, $message) = self::$internalMethods[$class][$method->name];
+                [$declaringClass, $message] = self::$internalMethods[$class][$method->name];
                if (strncmp($ns, $declaringClass, $len)) {
                    $deprecations[] = sprintf('The "%s::%s()" method is considered internal%s. It may change without further notice. You should not extend it from "%s".', $declaringClass, $method->name, $message, $class);
                }
@@ -375,7 +379,7 @@ class DebugClassLoader
            if ($finalOrInternal || $method->isConstructor() || false === strpos($doc, '@param') || StatelessInvocation::class === $class) {
                continue;
            }
-            if (!preg_match_all('#\n\s+\* @param +((?(?!callable *\().*?|callable *\(.*\).*?))(?<= )\$([a-zA-Z0-9_\x7f-\xff]++)#', $doc, $matches, PREG_SET_ORDER)) {
+            if (!preg_match_all('#\n\s+\* @param +((?(?!callable *\().*?|callable *\(.*\).*?))(?<= )\$([a-zA-Z0-9_\x7f-\xff]++)#', $doc, $matches, \PREG_SET_ORDER)) {
                continue;
            }
            if (!isset(self::$annotatedParameters[$class][$method->name])) {
@@ -384,10 +388,10 @@ class DebugClassLoader
                    $definedParameters[$parameter->name] = true;
                }
            }
-            foreach ($matches as list(, $parameterType, $parameterName)) {
+            foreach ($matches as [, $parameterType, $parameterName]) {
                if (!isset($definedParameters[$parameterName])) {
                    $parameterType = trim($parameterType);
-                    self::$annotatedParameters[$class][$method->name][$parameterName] = sprintf('The "%%s::%s()" method will require a new "%s$%s" argument in the next major version of its parent class "%s", not defining it is deprecated.', $method->name, $parameterType ? $parameterType.' ' : '', $parameterName, $method->class);
+                    self::$annotatedParameters[$class][$method->name][$parameterName] = sprintf('The "%%s::%s()" method will require a new "%s$%s" argument in the next major version of its %s "%s", not defining it is deprecated.', $method->name, $parameterType ? $parameterType.' ' : '', $parameterName, interface_exists($class) ? 'interface' : 'parent class', $method->class);
                }
            }
        }
@@ -395,6 +399,12 @@ class DebugClassLoader
        return $deprecations;
    }

+    /**
+     * @param string $file
+     * @param string $class
+     *
+     * @return array|null
+     */
    public function checkCase(\ReflectionClass $refl, $file, $class)
    {
        $real = explode('\\', $class.strrchr($file, '.'));
@@ -411,7 +421,7 @@ class DebugClassLoader
        array_splice($tail, 0, $i + 1);

        if (!$tail) {
-            return;
+            return null;
        }

        $tail = \DIRECTORY_SEPARATOR.implode(\DIRECTORY_SEPARATOR, $tail);
@@ -427,12 +437,14 @@ class DebugClassLoader
        ) {
            return [substr($tail, -$tailLen + 1), substr($real, -$tailLen + 1), substr($real, 0, -$tailLen + 1)];
        }
+
+        return null;
    }

    /**
     * `realpath` on MacOSX doesn't normalize the case of characters.
     */
-    private function darwinRealpath($real)
+    private function darwinRealpath(string $real): string
    {
        $i = 1 + strrpos($real, '/');
        $file = substr($real, $i);
@@ -447,7 +459,11 @@ class DebugClassLoader
                $real = self::$darwinCache[$kDir][0];
            } else {
                $dir = getcwd();
-                chdir($real);
+
+                if (!@chdir($real)) {
+                    return $real.$file;
+                }
+
                $real = getcwd().'/';
                chdir($dir);

@@ -474,7 +490,7 @@ class DebugClassLoader
        }

        if (isset($dirFiles[$file])) {
-            return $real .= $dirFiles[$file];
+            return $real.$dirFiles[$file];
        }

        $kFile = strtolower($file);
@@ -493,18 +509,15 @@ class DebugClassLoader
            self::$darwinCache[$kDir][1] = $dirFiles;
        }

-        return $real .= $dirFiles[$kFile];
+        return $real.$dirFiles[$kFile];
    }

    /**
     * `class_implements` includes interfaces from the parents so we have to manually exclude them.
     *
-     * @param string       $class
-     * @param string|false $parent
-     *
     * @return string[]
     */
-    private function getOwnInterfaces($class, $parent)
+    private function getOwnInterfaces(string $class, ?string $parent): array
    {
        $ownInterfaces = class_implements($class, false);

--- a/ErrorHandler.php
+++ b/ErrorHandler.php
@@ -23,6 +23,8 @@ use Symfony\Component\Debug\FatalErrorHandler\FatalErrorHandlerInterface;
 use Symfony\Component\Debug\FatalErrorHandler\UndefinedFunctionFatalErrorHandler;
 use Symfony\Component\Debug\FatalErrorHandler\UndefinedMethodFatalErrorHandler;

+@trigger_error(sprintf('The "%s" class is deprecated since Symfony 4.4, use "%s" instead.', ErrorHandler::class, \Symfony\Component\ErrorHandler\ErrorHandler::class), \E_USER_DEPRECATED);
+
 /**
 * A generic ErrorHandler for the PHP engine.
 *
@@ -47,43 +49,45 @@ use Symfony\Component\Debug\FatalErrorHandler\UndefinedMethodFatalErrorHandler;
 * @author Grégoire Pineau <lyrixx@lyrixx.info>
 *
 * @final since Symfony 4.3
+ *
+ * @deprecated since Symfony 4.4, use Symfony\Component\ErrorHandler\ErrorHandler instead.
 */
 class ErrorHandler
 {
    private $levels = [
-        E_DEPRECATED => 'Deprecated',
-        E_USER_DEPRECATED => 'User Deprecated',
-        E_NOTICE => 'Notice',
-        E_USER_NOTICE => 'User Notice',
-        E_STRICT => 'Runtime Notice',
-        E_WARNING => 'Warning',
-        E_USER_WARNING => 'User Warning',
-        E_COMPILE_WARNING => 'Compile Warning',
-        E_CORE_WARNING => 'Core Warning',
-        E_USER_ERROR => 'User Error',
-        E_RECOVERABLE_ERROR => 'Catchable Fatal Error',
-        E_COMPILE_ERROR => 'Compile Error',
-        E_PARSE => 'Parse Error',
-        E_ERROR => 'Error',
-        E_CORE_ERROR => 'Core Error',
+        \E_DEPRECATED => 'Deprecated',
+        \E_USER_DEPRECATED => 'User Deprecated',
+        \E_NOTICE => 'Notice',
+        \E_USER_NOTICE => 'User Notice',
+        \E_STRICT => 'Runtime Notice',
+        \E_WARNING => 'Warning',
+        \E_USER_WARNING => 'User Warning',
+        \E_COMPILE_WARNING => 'Compile Warning',
+        \E_CORE_WARNING => 'Core Warning',
+        \E_USER_ERROR => 'User Error',
+        \E_RECOVERABLE_ERROR => 'Catchable Fatal Error',
+        \E_COMPILE_ERROR => 'Compile Error',
+        \E_PARSE => 'Parse Error',
+        \E_ERROR => 'Error',
+        \E_CORE_ERROR => 'Core Error',
    ];

    private $loggers = [
-        E_DEPRECATED => [null, LogLevel::INFO],
-        E_USER_DEPRECATED => [null, LogLevel::INFO],
-        E_NOTICE => [null, LogLevel::WARNING],
-        E_USER_NOTICE => [null, LogLevel::WARNING],
-        E_STRICT => [null, LogLevel::WARNING],
-        E_WARNING => [null, LogLevel::WARNING],
-        E_USER_WARNING => [null, LogLevel::WARNING],
-        E_COMPILE_WARNING => [null, LogLevel::WARNING],
-        E_CORE_WARNING => [null, LogLevel::WARNING],
-        E_USER_ERROR => [null, LogLevel::CRITICAL],
-        E_RECOVERABLE_ERROR => [null, LogLevel::CRITICAL],
-        E_COMPILE_ERROR => [null, LogLevel::CRITICAL],
-        E_PARSE => [null, LogLevel::CRITICAL],
-        E_ERROR => [null, LogLevel::CRITICAL],
-        E_CORE_ERROR => [null, LogLevel::CRITICAL],
+        \E_DEPRECATED => [null, LogLevel::INFO],
+        \E_USER_DEPRECATED => [null, LogLevel::INFO],
+        \E_NOTICE => [null, LogLevel::WARNING],
+        \E_USER_NOTICE => [null, LogLevel::WARNING],
+        \E_STRICT => [null, LogLevel::WARNING],
+        \E_WARNING => [null, LogLevel::WARNING],
+        \E_USER_WARNING => [null, LogLevel::WARNING],
+        \E_COMPILE_WARNING => [null, LogLevel::WARNING],
+        \E_CORE_WARNING => [null, LogLevel::WARNING],
+        \E_USER_ERROR => [null, LogLevel::CRITICAL],
+        \E_RECOVERABLE_ERROR => [null, LogLevel::CRITICAL],
+        \E_COMPILE_ERROR => [null, LogLevel::CRITICAL],
+        \E_PARSE => [null, LogLevel::CRITICAL],
+        \E_ERROR => [null, LogLevel::CRITICAL],
+        \E_CORE_ERROR => [null, LogLevel::CRITICAL],
    ];

    private $thrownErrors = 0x1FFF; // E_ALL - E_DEPRECATED - E_USER_DEPRECATED
@@ -154,7 +158,7 @@ class ErrorHandler
            $handler->setExceptionHandler($prev);
        }

-        $handler->throwAt(E_ALL & $handler->thrownErrors, true);
+        $handler->throwAt(\E_ALL & $handler->thrownErrors, true);

        return $handler;
    }
@@ -165,18 +169,17 @@ class ErrorHandler
            $this->bootstrappingLogger = $bootstrappingLogger;
            $this->setDefaultLogger($bootstrappingLogger);
        }
-        $this->traceReflector = new \ReflectionProperty('Exception', 'trace');
+        $this->traceReflector = new \ReflectionProperty(\Exception::class, 'trace');
        $this->traceReflector->setAccessible(true);
    }

    /**
     * Sets a logger to non assigned errors levels.
     *
-     * @param LoggerInterface $logger  A PSR-3 logger to put as default for the given levels
-     * @param array|int       $levels  An array map of E_* to LogLevel::* or an integer bit field of E_* constants
-     * @param bool            $replace Whether to replace or not any existing logger
+     * @param array|int $levels  An array map of E_* to LogLevel::* or an integer bit field of E_* constants
+     * @param bool      $replace Whether to replace or not any existing logger
     */
-    public function setDefaultLogger(LoggerInterface $logger, $levels = E_ALL, $replace = false)
+    public function setDefaultLogger(LoggerInterface $logger, $levels = \E_ALL, $replace = false)
    {
        $loggers = [];

@@ -188,7 +191,7 @@ class ErrorHandler
            }
        } else {
            if (null === $levels) {
-                $levels = E_ALL;
+                $levels = \E_ALL;
            }
            foreach ($this->loggers as $type => $log) {
                if (($type & $levels) && (empty($log[0]) || $replace || $log[0] === $this->bootstrappingLogger)) {
@@ -223,14 +226,14 @@ class ErrorHandler
            if (!\is_array($log)) {
                $log = [$log];
            } elseif (!\array_key_exists(0, $log)) {
-                throw new \InvalidArgumentException('No logger provided');
+                throw new \InvalidArgumentException('No logger provided.');
            }
            if (null === $log[0]) {
                $this->loggedErrors &= ~$type;
            } elseif ($log[0] instanceof LoggerInterface) {
                $this->loggedErrors |= $type;
            } else {
-                throw new \InvalidArgumentException('Invalid logger provided');
+                throw new \InvalidArgumentException('Invalid logger provided.');
            }
            $this->loggers[$type] = $log + $prev[$type];

@@ -242,7 +245,7 @@ class ErrorHandler

        if ($flush) {
            foreach ($this->bootstrappingLogger->cleanLogs() as $log) {
-                $type = $log[2]['exception'] instanceof \ErrorException ? $log[2]['exception']->getSeverity() : E_ERROR;
+                $type = $log[2]['exception'] instanceof \ErrorException ? $log[2]['exception']->getSeverity() : \E_ERROR;
                if (!isset($flush[$type])) {
                    $this->bootstrappingLogger->log($log[0], $log[1], $log[2]);
                } elseif ($this->loggers[$type][0]) {
@@ -280,7 +283,7 @@ class ErrorHandler
    public function throwAt($levels, $replace = false)
    {
        $prev = $this->thrownErrors;
-        $this->thrownErrors = ($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 |= $prev;
        }
@@ -349,7 +352,7 @@ class ErrorHandler
    /**
     * Re-registers as a PHP error handler if levels changed.
     */
-    private function reRegister($prev)
+    private function reRegister(int $prev)
    {
        if ($prev !== $this->thrownErrors | $this->loggedErrors) {
            $handler = set_error_handler('var_dump');
@@ -382,16 +385,15 @@ class ErrorHandler
     */
    public function handleError($type, $message, $file, $line)
    {
-        // @deprecated to be removed in Symfony 5.0
-        if (\PHP_VERSION_ID >= 70300 && $message && '"' === $message[0] && 0 === strpos($message, '"continue') && preg_match('/^"continue(?: \d++)?" targeting switch is equivalent to "break(?: \d++)?"\. Did you mean to use "continue(?: \d++)?"\?$/', $message)) {
-            $type = E_DEPRECATED;
+        if (\PHP_VERSION_ID >= 70300 && \E_WARNING === $type && '"' === $message[0] && false !== strpos($message, '" targeting switch is equivalent to "break')) {
+            $type = \E_DEPRECATED;
        }

        // Level is the current error reporting level to manage silent error.
        $level = error_reporting();
        $silenced = 0 === ($level & $type);
        // Strong errors are not authorized to be silenced.
-        $level |= E_RECOVERABLE_ERROR | E_USER_ERROR | E_DEPRECATED | E_USER_DEPRECATED;
+        $level |= \E_RECOVERABLE_ERROR | \E_USER_ERROR | \E_DEPRECATED | \E_USER_DEPRECATED;
        $log = $this->loggedErrors & $type;
        $throw = $this->thrownErrors & $type & $level;
        $type &= $level | $this->screamedErrors;
@@ -401,19 +403,7 @@ class ErrorHandler
        }
        $scope = $this->scopedErrors & $type;

-        if (4 < $numArgs = \func_num_args()) {
-            $context = $scope ? (func_get_arg(4) ?: []) : [];
-        } else {
-            $context = [];
-        }
-
-        if (isset($context['GLOBALS']) && $scope) {
-            $e = $context;                  // Whatever the signature of the method,
-            unset($e['GLOBALS'], $context); // $context is always a reference in 5.3
-            $context = $e;
-        }
-
-        if (false !== strpos($message, "class@anonymous\0")) {
+        if (false !== strpos($message, "@anonymous\0")) {
            $logMessage = $this->levels[$type].': '.(new FlattenException())->setMessage($message)->getMessage();
        } else {
            $logMessage = $this->levels[$type].': '.$message;
@@ -424,7 +414,7 @@ class ErrorHandler
            self::$toStringException = null;
        } elseif (!$throw && !($type & $level)) {
            if (!isset(self::$silencedErrorCache[$id = $file.':'.$line])) {
-                $lightTrace = $this->tracedErrors & $type ? $this->cleanTrace(debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS, 5), $type, $file, $line, false) : [];
+                $lightTrace = $this->tracedErrors & $type ? $this->cleanTrace(debug_backtrace(\DEBUG_BACKTRACE_IGNORE_ARGS, 5), $type, $file, $line, false) : [];
                $errorAsException = new SilencedErrorContext($type, $file, $line, isset($lightTrace[1]) ? [$lightTrace[0]] : $lightTrace);
            } elseif (isset(self::$silencedErrorCache[$id][$message])) {
                $lightTrace = null;
@@ -443,7 +433,7 @@ class ErrorHandler
                self::$silencedErrorCache[$id][$message] = $errorAsException;
            }
            if (null === $lightTrace) {
-                return;
+                return true;
            }
        } else {
            $errorAsException = new \ErrorException($logMessage, 0, $type, $file, $line);
@@ -459,7 +449,7 @@ class ErrorHandler
        }

        if ($throw) {
-            if (E_USER_ERROR & $type) {
+            if (\PHP_VERSION_ID < 70400 && \E_USER_ERROR & $type) {
                for ($i = 1; isset($backtrace[$i]); ++$i) {
                    if (isset($backtrace[$i]['function'], $backtrace[$i]['type'], $backtrace[$i - 1]['function'])
                        && '__toString' === $backtrace[$i]['function']
@@ -474,6 +464,8 @@ class ErrorHandler
                        // `return trigger_error($e, E_USER_ERROR);` allows this error handler
                        // to make $e get through the __toString() barrier.

+                        $context = 4 < \func_num_args() ? (func_get_arg(4) ?: []) : [];
+
                        foreach ($context as $e) {
                            if ($e instanceof \Throwable && $e->__toString() === $message) {
                                self::$toStringException = $e;
@@ -497,7 +489,7 @@ class ErrorHandler
        if ($this->isRecursive) {
            $log = 0;
        } else {
-            if (!\defined('HHVM_VERSION')) {
+            if (\PHP_VERSION_ID < (\PHP_VERSION_ID < 70400 ? 70316 : 70404)) {
                $currentErrorHandler = set_error_handler('var_dump');
                restore_error_handler();
            }
@@ -509,7 +501,7 @@ class ErrorHandler
            } finally {
                $this->isRecursive = false;

-                if (!\defined('HHVM_VERSION')) {
+                if (\PHP_VERSION_ID < (\PHP_VERSION_ID < 70400 ? 70316 : 70404)) {
                    set_error_handler($currentErrorHandler);
                }
            }
@@ -534,11 +526,11 @@ class ErrorHandler
        if (!$exception instanceof \Exception) {
            $exception = new FatalThrowableError($exception);
        }
-        $type = $exception instanceof FatalErrorException ? $exception->getSeverity() : E_ERROR;
+        $type = $exception instanceof FatalErrorException ? $exception->getSeverity() : \E_ERROR;
        $handlerException = null;

        if (($this->loggedErrors & $type) || $exception instanceof FatalThrowableError) {
-            if (false !== strpos($message = $exception->getMessage(), "class@anonymous\0")) {
+            if (false !== strpos($message = $exception->getMessage(), "@anonymous\0")) {
                $message = (new FlattenException())->setMessage($message)->getMessage();
            }
            if ($exception instanceof FatalErrorException) {
@@ -576,7 +568,9 @@ class ErrorHandler
        $this->exceptionHandler = null;
        try {
            if (null !== $exceptionHandler) {
-                return $exceptionHandler($exception);
+                $exceptionHandler($exception);
+
+                return;
            }
            $handlerException = $handlerException ?: $exception;
        } catch (\Throwable $handlerException) {
@@ -639,10 +633,10 @@ class ErrorHandler
            $error = error_get_last();
        }

-        if ($error && $error['type'] &= E_PARSE | E_ERROR | E_CORE_ERROR | E_COMPILE_ERROR) {
+        if ($error && $error['type'] &= \E_PARSE | \E_ERROR | \E_CORE_ERROR | \E_COMPILE_ERROR) {
            // Let's not throw anymore but keep logging
            $handler->throwAt(0, true);
-            $trace = isset($error['backtrace']) ? $error['backtrace'] : null;
+            $trace = $error['backtrace'] ?? null;

            if (0 === strpos($error['message'], 'Allowed memory') || 0 === strpos($error['message'], 'Out of memory')) {
                $exception = new OutOfMemoryException($handler->levels[$error['type']].': '.$error['message'], 0, $error['type'], $error['file'], $error['line'], 2, false, $trace);
@@ -687,7 +681,7 @@ class ErrorHandler
    /**
     * Cleans the trace by removing function arguments and the frames added by the error handler and DebugClassLoader.
     */
-    private function cleanTrace($backtrace, $type, $file, $line, $throw)
+    private function cleanTrace(array $backtrace, int $type, string $file, int $line, bool $throw): array
    {
        $lightTrace = $backtrace;

--- a/Exception/ClassNotFoundException.php
+++ b/Exception/ClassNotFoundException.php
@@ -11,10 +11,14 @@

 namespace Symfony\Component\Debug\Exception;

+@trigger_error(sprintf('The "%s" class is deprecated since Symfony 4.4, use "%s" instead.', ClassNotFoundException::class, \Symfony\Component\ErrorHandler\Error\ClassNotFoundError::class), \E_USER_DEPRECATED);
+
 /**
 * Class (or Trait or Interface) Not Found Exception.
 *
 * @author Konstanton Myakshin <koc-dp@yandex.ru>
+ *
+ * @deprecated since Symfony 4.4, use Symfony\Component\ErrorHandler\Error\ClassNotFoundError instead.
 */
 class ClassNotFoundException extends FatalErrorException
 {
--- a/Exception/FatalErrorException.php
+++ b/Exception/FatalErrorException.php
@@ -11,10 +11,14 @@

 namespace Symfony\Component\Debug\Exception;

+@trigger_error(sprintf('The "%s" class is deprecated since Symfony 4.4, use "%s" instead.', FatalErrorException::class, \Symfony\Component\ErrorHandler\Error\FatalError::class), \E_USER_DEPRECATED);
+
 /**
 * Fatal Error Exception.
 *
 * @author Konstanton Myakshin <koc-dp@yandex.ru>
+ *
+ * @deprecated since Symfony 4.4, use Symfony\Component\ErrorHandler\Error\FatalError instead.
 */
 class FatalErrorException extends \ErrorException
 {
@@ -31,8 +35,7 @@ class FatalErrorException extends \ErrorException

            $this->setTrace($trace);
        } elseif (null !== $traceOffset) {
-            if (\function_exists('xdebug_get_function_stack')) {
-                $trace = xdebug_get_function_stack();
+            if (\function_exists('xdebug_get_function_stack') && $trace = @xdebug_get_function_stack()) {
                if (0 < $traceOffset) {
                    array_splice($trace, -$traceOffset);
                }
@@ -70,7 +73,7 @@ class FatalErrorException extends \ErrorException

    protected function setTrace($trace)
    {
-        $traceReflector = new \ReflectionProperty('Exception', 'trace');
+        $traceReflector = new \ReflectionProperty(\Exception::class, 'trace');
        $traceReflector->setAccessible(true);
        $traceReflector->setValue($this, $trace);
    }
--- a/Exception/FatalThrowableError.php
+++ b/Exception/FatalThrowableError.php
@@ -11,10 +11,14 @@

 namespace Symfony\Component\Debug\Exception;

+@trigger_error(sprintf('The "%s" class is deprecated since Symfony 4.4.', FatalThrowableError::class), \E_USER_DEPRECATED);
+
 /**
 * Fatal Throwable Error.
 *
 * @author Nicolas Grekas <p@tchwork.com>
+ *
+ * @deprecated since Symfony 4.4
 */
 class FatalThrowableError extends FatalErrorException
 {
@@ -25,11 +29,11 @@ class FatalThrowableError extends FatalErrorException
        $this->originalClassName = \get_class($e);

        if ($e instanceof \ParseError) {
-            $severity = E_PARSE;
+            $severity = \E_PARSE;
        } elseif ($e instanceof \TypeError) {
-            $severity = E_RECOVERABLE_ERROR;
+            $severity = \E_RECOVERABLE_ERROR;
        } else {
-            $severity = E_ERROR;
+            $severity = \E_ERROR;
        }

        \ErrorException::__construct(
--- a/Exception/FlattenException.php
+++ b/Exception/FlattenException.php
@@ -20,6 +20,8 @@ use Symfony\Component\HttpKernel\Exception\HttpExceptionInterface;
 * Basically, this class removes all objects from the trace.
 *
 * @author Fabien Potencier <fabien@symfony.com>
+ *
+ * @deprecated since Symfony 4.4, use Symfony\Component\ErrorHandler\Exception\FlattenException instead.
 */
 class FlattenException
 {
@@ -34,12 +36,18 @@ class FlattenException
    private $file;
    private $line;

+    /**
+     * @return static
+     */
    public static function create(\Exception $exception, $statusCode = null, array $headers = [])
    {
        return static::createFromThrowable($exception, $statusCode, $headers);
    }

-    public static function createFromThrowable(\Throwable $exception, ?int $statusCode = null, array $headers = []): self
+    /**
+     * @return static
+     */
+    public static function createFromThrowable(\Throwable $exception, int $statusCode = null, array $headers = [])
    {
        $e = new static();
        $e->setMessage($exception->getMessage());
@@ -126,7 +134,7 @@ class FlattenException
     */
    public function setClass($class)
    {
-        $this->class = 'c' === $class[0] && 0 === strpos($class, "class@anonymous\0") ? get_parent_class($class).'@anonymous' : $class;
+        $this->class = false !== strpos($class, "@anonymous\0") ? (get_parent_class($class) ?: key(class_implements($class)) ?: 'class').'@anonymous' : $class;

        return $this;
    }
@@ -171,9 +179,9 @@ class FlattenException
     */
    public function setMessage($message)
    {
-        if (false !== strpos($message, "class@anonymous\0")) {
-            $message = preg_replace_callback('/class@anonymous\x00.*?\.php0x?[0-9a-fA-F]++/', function ($m) {
-                return class_exists($m[0], false) ? get_parent_class($m[0]).'@anonymous' : $m[0];
+        if (false !== strpos($message, "@anonymous\0")) {
+            $message = preg_replace_callback('/[a-zA-Z_\x7f-\xff][\\\\a-zA-Z0-9_\x7f-\xff]*+@anonymous\x00.*?\.php(?:0x?|:[0-9]++\$)[0-9a-fA-F]++/', function ($m) {
+                return class_exists($m[0], false) ? (get_parent_class($m[0]) ?: key(class_implements($m[0])) ?: 'class').'@anonymous' : $m[0];
            }, $message);
        }

@@ -233,7 +241,7 @@ class FlattenException
     */
    public function setTraceFromException(\Exception $exception)
    {
-        @trigger_error(sprintf('The "%s()" method is deprecated since Symfony 4.1, use "setTraceFromThrowable()" instead.', __METHOD__), E_USER_DEPRECATED);
+        @trigger_error(sprintf('The "%s()" method is deprecated since Symfony 4.1, use "setTraceFromThrowable()" instead.', __METHOD__), \E_USER_DEPRECATED);

        $this->setTraceFromThrowable($exception);
    }
@@ -273,11 +281,11 @@ class FlattenException
            $this->trace[] = [
                'namespace' => $namespace,
                'short_class' => $class,
-                'class' => isset($entry['class']) ? $entry['class'] : '',
-                'type' => isset($entry['type']) ? $entry['type'] : '',
-                'function' => isset($entry['function']) ? $entry['function'] : null,
-                'file' => isset($entry['file']) ? $entry['file'] : null,
-                'line' => isset($entry['line']) ? $entry['line'] : null,
+                'class' => $entry['class'] ?? '',
+                'type' => $entry['type'] ?? '',
+                'function' => $entry['function'] ?? null,
+                'file' => $entry['file'] ?? null,
+                'line' => $entry['line'] ?? null,
                'args' => isset($entry['args']) ? $this->flattenArgs($entry['args']) : [],
            ];
        }
@@ -285,7 +293,7 @@ class FlattenException
        return $this;
    }

-    private function flattenArgs($args, $level = 0, &$count = 0)
+    private function flattenArgs(array $args, int $level = 0, int &$count = 0): array
    {
        $result = [];
        foreach ($args as $key => $value) {
@@ -321,7 +329,7 @@ class FlattenException
        return $result;
    }

-    private function getClassNameFromIncomplete(\__PHP_Incomplete_Class $value)
+    private function getClassNameFromIncomplete(\__PHP_Incomplete_Class $value): string
    {
        $array = new \ArrayObject($value);

--- a/Exception/OutOfMemoryException.php
+++ b/Exception/OutOfMemoryException.php
@@ -11,10 +11,14 @@

 namespace Symfony\Component\Debug\Exception;

+@trigger_error(sprintf('The "%s" class is deprecated since Symfony 4.4, use "%s" instead.', OutOfMemoryException::class, \Symfony\Component\ErrorHandler\Error\OutOfMemoryError::class), \E_USER_DEPRECATED);
+
 /**
 * Out of memory exception.
 *
 * @author Nicolas Grekas <p@tchwork.com>
+ *
+ * @deprecated since Symfony 4.4, use Symfony\Component\ErrorHandler\Error\OutOfMemoryError instead.
 */
 class OutOfMemoryException extends FatalErrorException
 {
--- a/Exception/SilencedErrorContext.php
+++ b/Exception/SilencedErrorContext.php
@@ -11,10 +11,14 @@

 namespace Symfony\Component\Debug\Exception;

+@trigger_error(sprintf('The "%s" class is deprecated since Symfony 4.4, use "%s" instead.', SilencedErrorContext::class, \Symfony\Component\ErrorHandler\Exception\SilencedErrorContext::class), \E_USER_DEPRECATED);
+
 /**
 * Data Object that represents a Silenced Error.
 *
 * @author Grégoire Pineau <lyrixx@lyrixx.info>
+ *
+ * @deprecated since Symfony 4.4, use Symfony\Component\ErrorHandler\Exception\SilencedErrorContext instead.
 */
 class SilencedErrorContext implements \JsonSerializable
 {
@@ -54,7 +58,7 @@ class SilencedErrorContext implements \JsonSerializable
        return $this->trace;
    }

-    public function JsonSerialize()
+    public function jsonSerialize()
    {
        return [
            'severity' => $this->severity,
--- a/Exception/UndefinedFunctionException.php
+++ b/Exception/UndefinedFunctionException.php
@@ -11,10 +11,14 @@

 namespace Symfony\Component\Debug\Exception;

+@trigger_error(sprintf('The "%s" class is deprecated since Symfony 4.4, use "%s" instead.', UndefinedFunctionException::class, \Symfony\Component\ErrorHandler\Error\UndefinedFunctionError::class), \E_USER_DEPRECATED);
+
 /**
 * Undefined Function Exception.
 *
 * @author Konstanton Myakshin <koc-dp@yandex.ru>
+ *
+ * @deprecated since Symfony 4.4, use Symfony\Component\ErrorHandler\Error\UndefinedFunctionError instead.
 */
 class UndefinedFunctionException extends FatalErrorException
 {
--- a/Exception/UndefinedMethodException.php
+++ b/Exception/UndefinedMethodException.php
@@ -11,10 +11,14 @@

 namespace Symfony\Component\Debug\Exception;

+@trigger_error(sprintf('The "%s" class is deprecated since Symfony 4.4, use "%s" instead.', UndefinedMethodException::class, \Symfony\Component\ErrorHandler\Error\UndefinedMethodError::class), \E_USER_DEPRECATED);
+
 /**
 * Undefined Method Exception.
 *
 * @author Grégoire Pineau <lyrixx@lyrixx.info>
+ *
+ * @deprecated since Symfony 4.4, use Symfony\Component\ErrorHandler\Error\UndefinedMethodError instead.
 */
 class UndefinedMethodException extends FatalErrorException
 {
--- a/ExceptionHandler.php
+++ b/ExceptionHandler.php
--- a/FatalErrorHandler/ClassNotFoundFatalErrorHandler.php
+++ b/FatalErrorHandler/ClassNotFoundFatalErrorHandler.php
@@ -17,10 +17,14 @@ use Symfony\Component\Debug\DebugClassLoader;
 use Symfony\Component\Debug\Exception\ClassNotFoundException;
 use Symfony\Component\Debug\Exception\FatalErrorException;

+@trigger_error(sprintf('The "%s" class is deprecated since Symfony 4.4, use "%s" instead.', ClassNotFoundFatalErrorHandler::class, \Symfony\Component\ErrorHandler\FatalErrorHandler\ClassNotFoundFatalErrorHandler::class), \E_USER_DEPRECATED);
+
 /**
 * ErrorHandler for classes that do not exist.
 *
 * @author Fabien Potencier <fabien@symfony.com>
+ *
+ * @deprecated since Symfony 4.4, use Symfony\Component\ErrorHandler\FatalErrorHandler\ClassNotFoundFatalErrorHandler instead.
 */
 class ClassNotFoundFatalErrorHandler implements FatalErrorHandlerInterface
 {
@@ -29,48 +33,34 @@ class ClassNotFoundFatalErrorHandler implements FatalErrorHandlerInterface
     */
    public function handleError(array $error, FatalErrorException $exception)
    {
-        $messageLen = \strlen($error['message']);
-        $notFoundSuffix = '\' not found';
-        $notFoundSuffixLen = \strlen($notFoundSuffix);
-        if ($notFoundSuffixLen > $messageLen) {
-            return;
+        if (!preg_match('/^(Class|Interface|Trait) [\'"]([^\'"]+)[\'"] not found$/', $error['message'], $matches)) {
+            return null;
+        }
+        $typeName = strtolower($matches[1]);
+        $fullyQualifiedClassName = $matches[2];
+
+        if (false !== $namespaceSeparatorIndex = strrpos($fullyQualifiedClassName, '\\')) {
+            $className = substr($fullyQualifiedClassName, $namespaceSeparatorIndex + 1);
+            $namespacePrefix = substr($fullyQualifiedClassName, 0, $namespaceSeparatorIndex);
+            $message = sprintf('Attempted to load %s "%s" from namespace "%s".', $typeName, $className, $namespacePrefix);
+            $tail = ' for another namespace?';
+        } else {
+            $className = $fullyQualifiedClassName;
+            $message = sprintf('Attempted to load %s "%s" from the global namespace.', $typeName, $className);
+            $tail = '?';
        }

-        if (0 !== substr_compare($error['message'], $notFoundSuffix, -$notFoundSuffixLen)) {
-            return;
-        }
-
-        foreach (['class', 'interface', 'trait'] as $typeName) {
-            $prefix = ucfirst($typeName).' \'';
-            $prefixLen = \strlen($prefix);
-            if (0 !== strpos($error['message'], $prefix)) {
-                continue;
-            }
-
-            $fullyQualifiedClassName = substr($error['message'], $prefixLen, -$notFoundSuffixLen);
-            if (false !== $namespaceSeparatorIndex = strrpos($fullyQualifiedClassName, '\\')) {
-                $className = substr($fullyQualifiedClassName, $namespaceSeparatorIndex + 1);
-                $namespacePrefix = substr($fullyQualifiedClassName, 0, $namespaceSeparatorIndex);
-                $message = sprintf('Attempted to load %s "%s" from namespace "%s".', $typeName, $className, $namespacePrefix);
-                $tail = ' for another namespace?';
+        if ($candidates = $this->getClassCandidates($className)) {
+            $tail = array_pop($candidates).'"?';
+            if ($candidates) {
+                $tail = ' for e.g. "'.implode('", "', $candidates).'" or "'.$tail;
            } else {
-                $className = $fullyQualifiedClassName;
-                $message = sprintf('Attempted to load %s "%s" from the global namespace.', $typeName, $className);
-                $tail = '?';
+                $tail = ' for "'.$tail;
            }
-
-            if ($candidates = $this->getClassCandidates($className)) {
-                $tail = array_pop($candidates).'"?';
-                if ($candidates) {
-                    $tail = ' for e.g. "'.implode('", "', $candidates).'" or "'.$tail;
-                } else {
-                    $tail = ' for "'.$tail;
-                }
-            }
-            $message .= "\nDid you forget a \"use\" statement".$tail;
-
-            return new ClassNotFoundException($message, $exception);
        }
+        $message .= "\nDid you forget a \"use\" statement".$tail;
+
+        return new ClassNotFoundException($message, $exception);
    }

    /**
--- a/FatalErrorHandler/FatalErrorHandlerInterface.php
+++ b/FatalErrorHandler/FatalErrorHandlerInterface.php
@@ -13,18 +13,21 @@ namespace Symfony\Component\Debug\FatalErrorHandler;

 use Symfony\Component\Debug\Exception\FatalErrorException;

+@trigger_error(sprintf('The "%s" class is deprecated since Symfony 4.4, use "%s" instead.', FatalErrorHandlerInterface::class, \Symfony\Component\ErrorHandler\FatalErrorHandler\FatalErrorHandlerInterface::class), \E_USER_DEPRECATED);
+
 /**
 * Attempts to convert fatal errors to exceptions.
 *
 * @author Fabien Potencier <fabien@symfony.com>
+ *
+ * @deprecated since Symfony 4.4, use Symfony\Component\ErrorHandler\FatalErrorHandler\FatalErrorHandlerInterface instead.
 */
 interface FatalErrorHandlerInterface
 {
    /**
     * Attempts to convert an error into an exception.
     *
-     * @param array               $error     An array as returned by error_get_last()
-     * @param FatalErrorException $exception A FatalErrorException instance
+     * @param array $error An array as returned by error_get_last()
     *
     * @return FatalErrorException|null A FatalErrorException instance if the class is able to convert the error, null otherwise
     */
--- a/FatalErrorHandler/UndefinedFunctionFatalErrorHandler.php
+++ b/FatalErrorHandler/UndefinedFunctionFatalErrorHandler.php
@@ -14,10 +14,14 @@ namespace Symfony\Component\Debug\FatalErrorHandler;
 use Symfony\Component\Debug\Exception\FatalErrorException;
 use Symfony\Component\Debug\Exception\UndefinedFunctionException;

+@trigger_error(sprintf('The "%s" class is deprecated since Symfony 4.4, use "%s" instead.', UndefinedFunctionFatalErrorHandler::class, \Symfony\Component\ErrorHandler\ErrorEnhancer\UndefinedFunctionErrorEnhancer::class), \E_USER_DEPRECATED);
+
 /**
 * ErrorHandler for undefined functions.
 *
 * @author Fabien Potencier <fabien@symfony.com>
+ *
+ * @deprecated since Symfony 4.4, use Symfony\Component\ErrorHandler\ErrorEnhancer\UndefinedFunctionErrorEnhancer instead.
 */
 class UndefinedFunctionFatalErrorHandler implements FatalErrorHandlerInterface
 {
@@ -30,17 +34,17 @@ class UndefinedFunctionFatalErrorHandler implements FatalErrorHandlerInterface
        $notFoundSuffix = '()';
        $notFoundSuffixLen = \strlen($notFoundSuffix);
        if ($notFoundSuffixLen > $messageLen) {
-            return;
+            return null;
        }

        if (0 !== substr_compare($error['message'], $notFoundSuffix, -$notFoundSuffixLen)) {
-            return;
+            return null;
        }

        $prefix = 'Call to undefined function ';
        $prefixLen = \strlen($prefix);
        if (0 !== strpos($error['message'], $prefix)) {
-            return;
+            return null;
        }

        $fullyQualifiedFunctionName = substr($error['message'], $prefixLen, -$notFoundSuffixLen);
--- a/FatalErrorHandler/UndefinedMethodFatalErrorHandler.php
+++ b/FatalErrorHandler/UndefinedMethodFatalErrorHandler.php
@@ -14,10 +14,14 @@ namespace Symfony\Component\Debug\FatalErrorHandler;
 use Symfony\Component\Debug\Exception\FatalErrorException;
 use Symfony\Component\Debug\Exception\UndefinedMethodException;

+@trigger_error(sprintf('The "%s" class is deprecated since Symfony 4.4, use "%s" instead.', UndefinedMethodFatalErrorHandler::class, \Symfony\Component\ErrorHandler\ErrorEnhancer\UndefinedMethodErrorEnhancer::class), \E_USER_DEPRECATED);
+
 /**
 * ErrorHandler for undefined methods.
 *
 * @author Grégoire Pineau <lyrixx@lyrixx.info>
+ *
+ * @deprecated since Symfony 4.4, use Symfony\Component\ErrorHandler\ErrorEnhancer\UndefinedMethodErrorEnhancer instead.
 */
 class UndefinedMethodFatalErrorHandler implements FatalErrorHandlerInterface
 {
@@ -28,7 +32,7 @@ class UndefinedMethodFatalErrorHandler implements FatalErrorHandlerInterface
    {
        preg_match('/^Call to undefined method (.*)::(.*)\(\)$/', $error['message'], $matches);
        if (!$matches) {
-            return;
+            return null;
        }

        $className = $matches[1];
@@ -36,7 +40,7 @@ class UndefinedMethodFatalErrorHandler implements FatalErrorHandlerInterface

        $message = sprintf('Attempted to call an undefined method named "%s" of class "%s".', $methodName, $className);

-        if (!class_exists($className) || null === $methods = get_class_methods($className)) {
+        if ('' === $methodName || !class_exists($className) || null === $methods = get_class_methods($className)) {
            // failed to get the class or its methods on which an unknown method was called (for example on an anonymous class)
            return new UndefinedMethodException($message, $exception);
        }
--- a/2
+++ b/2
@@ -1,4 +1,4 @@
-Copyright (c) 2004-2019 Fabien Potencier
+Copyright (c) 2004-2021 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
--- a/README.md
+++ b/README.md
@@ -1,13 +1,30 @@
 Debug Component
 ===============

+**CAUTION**: this component is deprecated since Symfony 4.4. Instead, use the
+[ErrorHandler component](https://github.com/symfony/symfony/tree/master/src/Symfony/Component/ErrorHandler).
+
+-----
+
 The Debug component provides tools to ease debugging PHP code.

+Getting Started
+---------------
+
+```
+$ composer install symfony/debug
+```
+
+```php
+use Symfony\Component\Debug\Debug;
+
+Debug::enable();
+```
+
 Resources
 ---------

-  * [Documentation](https://symfony.com/doc/current/components/debug/index.html)
-  * [Contributing](https://symfony.com/doc/current/contributing/index.html)
-  * [Report issues](https://github.com/symfony/symfony/issues) and
-    [send Pull Requests](https://github.com/symfony/symfony/pulls)
-    in the [main Symfony repository](https://github.com/symfony/symfony)
+ * [Contributing](https://symfony.com/doc/current/contributing/index.html)
+ * [Report issues](https://github.com/symfony/symfony/issues) and
+   [send Pull Requests](https://github.com/symfony/symfony/pulls)
+   in the [main Symfony repository](https://github.com/symfony/symfony)
--- a/Tests/DebugClassLoaderTest.php
+++ b/Tests/DebugClassLoaderTest.php
@@ -12,8 +12,12 @@
 namespace Symfony\Component\Debug\Tests;

 use PHPUnit\Framework\TestCase;
+use Symfony\Bridge\Debug\Tests\Fixtures\ExtendsDeprecatedParent;
 use Symfony\Component\Debug\DebugClassLoader;

+/**
+ * @group legacy
+ */
 class DebugClassLoaderTest extends TestCase
 {
    /**
@@ -23,24 +27,26 @@ class DebugClassLoaderTest extends TestCase

    private $loader;

-    protected function setUp()
+    protected function setUp(): void
    {
        $this->errorReporting = error_reporting(E_ALL);
-        $this->loader = new ClassLoader();
-        spl_autoload_register([$this->loader, 'loadClass'], true, true);
-        DebugClassLoader::enable();
+        $this->loader = [new DebugClassLoader([new ClassLoader(), 'loadClass']), 'loadClass'];
+        spl_autoload_register($this->loader, true, true);
    }

-    protected function tearDown()
+    protected function tearDown(): void
    {
-        DebugClassLoader::disable();
-        spl_autoload_unregister([$this->loader, 'loadClass']);
+        spl_autoload_unregister($this->loader);
        error_reporting($this->errorReporting);
    }

+    /**
+     * @runInSeparateProcess
+     */
    public function testIdempotence()
    {
        DebugClassLoader::enable();
+        DebugClassLoader::enable();

        $functions = spl_autoload_functions();
        foreach ($functions as $function) {
@@ -49,7 +55,7 @@ class DebugClassLoaderTest extends TestCase
                $reflProp = $reflClass->getProperty('classLoader');
                $reflProp->setAccessible(true);

-                $this->assertNotInstanceOf('Symfony\Component\Debug\DebugClassLoader', $reflProp->getValue($function[0]));
+                $this->assertNotInstanceOf(DebugClassLoader::class, $reflProp->getValue($function[0]));

                return;
            }
@@ -58,49 +64,43 @@ class DebugClassLoaderTest extends TestCase
        $this->fail('DebugClassLoader did not register');
    }

-    /**
-     * @expectedException \Exception
-     * @expectedExceptionMessage boo
-     */
    public function testThrowingClass()
    {
+        $this->expectException(\Exception::class);
+        $this->expectExceptionMessage('boo');
        try {
-            class_exists(__NAMESPACE__.'\Fixtures\Throwing');
+            class_exists(Fixtures\Throwing::class);
            $this->fail('Exception expected');
        } catch (\Exception $e) {
            $this->assertSame('boo', $e->getMessage());
        }

        // the second call also should throw
-        class_exists(__NAMESPACE__.'\Fixtures\Throwing');
+        class_exists(Fixtures\Throwing::class);
    }

-    /**
-     * @expectedException \RuntimeException
-     */
    public function testNameCaseMismatch()
    {
-        class_exists(__NAMESPACE__.'\TestingCaseMismatch', true);
+        $this->expectException(\RuntimeException::class);
+        $this->expectExceptionMessage('Case mismatch between loaded and declared class names');
+        class_exists(TestingCaseMismatch::class, true);
    }

-    /**
-     * @expectedException \RuntimeException
-     * @expectedExceptionMessage Case mismatch between class and real file names
-     */
    public function testFileCaseMismatch()
    {
+        $this->expectException(\RuntimeException::class);
+        $this->expectExceptionMessage('Case mismatch between class and real file names');
        if (!file_exists(__DIR__.'/Fixtures/CaseMismatch.php')) {
            $this->markTestSkipped('Can only be run on case insensitive filesystems');
        }

-        class_exists(__NAMESPACE__.'\Fixtures\CaseMismatch', true);
+        class_exists(Fixtures\CaseMismatch::class, true);
    }

-    /**
-     * @expectedException \RuntimeException
-     */
    public function testPsr4CaseMismatch()
    {
+        $this->expectException(\RuntimeException::class);
+        $this->expectExceptionMessage('Case mismatch between loaded and declared class names');
        class_exists(__NAMESPACE__.'\Fixtures\Psr4CaseMismatch', true);
    }

@@ -116,7 +116,7 @@ class DebugClassLoaderTest extends TestCase

    public function testClassAlias()
    {
-        $this->assertTrue(class_exists(__NAMESPACE__.'\Fixtures\ClassAlias', true));
+        $this->assertTrue(class_exists(Fixtures\ClassAlias::class, true));
    }

    /**
@@ -158,7 +158,7 @@ class DebugClassLoaderTest extends TestCase
        $e = error_reporting(0);
        trigger_error('', E_USER_NOTICE);

-        class_exists('Test\\'.__NAMESPACE__.'\\NonDeprecatedInterfaceClass', true);
+        class_exists('Test\\'.NonDeprecatedInterfaceClass::class, true);

        error_reporting($e);
        restore_error_handler();
@@ -180,7 +180,7 @@ class DebugClassLoaderTest extends TestCase
        $e = error_reporting(0);
        trigger_error('', E_USER_NOTICE);

-        class_exists('Symfony\Bridge\Debug\Tests\Fixtures\ExtendsDeprecatedParent', true);
+        class_exists(ExtendsDeprecatedParent::class, true);

        error_reporting($e);
        restore_error_handler();
@@ -205,7 +205,7 @@ class DebugClassLoaderTest extends TestCase
        require __DIR__.'/Fixtures/FinalClasses.php';

        $i = 1;
-        while (class_exists($finalClass = __NAMESPACE__.'\\Fixtures\\FinalClass'.$i++, false)) {
+        while (class_exists($finalClass = Fixtures\FinalClass::class.$i++, false)) {
            spl_autoload_call($finalClass);
            class_exists('Test\\'.__NAMESPACE__.'\\Extends'.substr($finalClass, strrpos($finalClass, '\\') + 1), true);
        }
@@ -231,7 +231,7 @@ class DebugClassLoaderTest extends TestCase
        set_error_handler(function ($type, $msg) use (&$deprecations) { $deprecations[] = $msg; });
        $e = error_reporting(E_USER_DEPRECATED);

-        class_exists(__NAMESPACE__.'\\Fixtures\\ExtendedFinalMethod', true);
+        class_exists(Fixtures\ExtendedFinalMethod::class, true);

        error_reporting($e);
        restore_error_handler();
@@ -250,7 +250,7 @@ class DebugClassLoaderTest extends TestCase
        $e = error_reporting(0);
        trigger_error('', E_USER_NOTICE);

-        class_exists('Test\\'.__NAMESPACE__.'\\ExtendsAnnotatedClass', true);
+        class_exists('Test\\'.ExtendsAnnotatedClass::class, true);

        error_reporting($e);
        restore_error_handler();
@@ -267,7 +267,7 @@ class DebugClassLoaderTest extends TestCase
        set_error_handler(function ($type, $msg) use (&$deprecations) { $deprecations[] = $msg; });
        $e = error_reporting(E_USER_DEPRECATED);

-        class_exists('Test\\'.__NAMESPACE__.'\\ExtendsInternals', true);
+        class_exists('Test\\'.ExtendsInternals::class, true);

        error_reporting($e);
        restore_error_handler();
@@ -286,19 +286,19 @@ class DebugClassLoaderTest extends TestCase
        set_error_handler(function ($type, $msg) use (&$deprecations) { $deprecations[] = $msg; });
        $e = error_reporting(E_USER_DEPRECATED);

-        class_exists(__NAMESPACE__.'\\Fixtures\SubClassWithAnnotatedParameters', true);
+        class_exists(Fixtures\SubClassWithAnnotatedParameters::class, true);

        error_reporting($e);
        restore_error_handler();

        $this->assertSame([
            'The "Symfony\Component\Debug\Tests\Fixtures\SubClassWithAnnotatedParameters::quzMethod()" method will require a new "Quz $quz" argument in the next major version of its parent class "Symfony\Component\Debug\Tests\Fixtures\ClassWithAnnotatedParameters", not defining it is deprecated.',
-            'The "Symfony\Component\Debug\Tests\Fixtures\SubClassWithAnnotatedParameters::whereAmI()" method will require a new "bool $matrix" argument in the next major version of its parent class "Symfony\Component\Debug\Tests\Fixtures\InterfaceWithAnnotatedParameters", not defining it is deprecated.',
-            'The "Symfony\Component\Debug\Tests\Fixtures\SubClassWithAnnotatedParameters::iAmHere()" method will require a new "$noType" argument in the next major version of its parent class "Symfony\Component\Debug\Tests\Fixtures\InterfaceWithAnnotatedParameters", not defining it is deprecated.',
-            'The "Symfony\Component\Debug\Tests\Fixtures\SubClassWithAnnotatedParameters::iAmHere()" method will require a new "callable(\Throwable|null $reason, mixed $value) $callback" argument in the next major version of its parent class "Symfony\Component\Debug\Tests\Fixtures\InterfaceWithAnnotatedParameters", not defining it is deprecated.',
-            'The "Symfony\Component\Debug\Tests\Fixtures\SubClassWithAnnotatedParameters::iAmHere()" method will require a new "string $param" argument in the next major version of its parent class "Symfony\Component\Debug\Tests\Fixtures\InterfaceWithAnnotatedParameters", not defining it is deprecated.',
-            'The "Symfony\Component\Debug\Tests\Fixtures\SubClassWithAnnotatedParameters::iAmHere()" method will require a new "callable  ($a,  $b) $anotherOne" argument in the next major version of its parent class "Symfony\Component\Debug\Tests\Fixtures\InterfaceWithAnnotatedParameters", not defining it is deprecated.',
-            'The "Symfony\Component\Debug\Tests\Fixtures\SubClassWithAnnotatedParameters::iAmHere()" method will require a new "Type$WithDollarIsStillAType $ccc" argument in the next major version of its parent class "Symfony\Component\Debug\Tests\Fixtures\InterfaceWithAnnotatedParameters", not defining it is deprecated.',
+            'The "Symfony\Component\Debug\Tests\Fixtures\SubClassWithAnnotatedParameters::whereAmI()" method will require a new "bool $matrix" argument in the next major version of its interface "Symfony\Component\Debug\Tests\Fixtures\InterfaceWithAnnotatedParameters", not defining it is deprecated.',
+            'The "Symfony\Component\Debug\Tests\Fixtures\SubClassWithAnnotatedParameters::iAmHere()" method will require a new "$noType" argument in the next major version of its interface "Symfony\Component\Debug\Tests\Fixtures\InterfaceWithAnnotatedParameters", not defining it is deprecated.',
+            'The "Symfony\Component\Debug\Tests\Fixtures\SubClassWithAnnotatedParameters::iAmHere()" method will require a new "callable(\Throwable|null $reason, mixed $value) $callback" argument in the next major version of its interface "Symfony\Component\Debug\Tests\Fixtures\InterfaceWithAnnotatedParameters", not defining it is deprecated.',
+            'The "Symfony\Component\Debug\Tests\Fixtures\SubClassWithAnnotatedParameters::iAmHere()" method will require a new "string $param" argument in the next major version of its interface "Symfony\Component\Debug\Tests\Fixtures\InterfaceWithAnnotatedParameters", not defining it is deprecated.',
+            'The "Symfony\Component\Debug\Tests\Fixtures\SubClassWithAnnotatedParameters::iAmHere()" method will require a new "callable  ($a,  $b) $anotherOne" argument in the next major version of its interface "Symfony\Component\Debug\Tests\Fixtures\InterfaceWithAnnotatedParameters", not defining it is deprecated.',
+            'The "Symfony\Component\Debug\Tests\Fixtures\SubClassWithAnnotatedParameters::iAmHere()" method will require a new "Type$WithDollarIsStillAType $ccc" argument in the next major version of its interface "Symfony\Component\Debug\Tests\Fixtures\InterfaceWithAnnotatedParameters", not defining it is deprecated.',
            'The "Symfony\Component\Debug\Tests\Fixtures\SubClassWithAnnotatedParameters::isSymfony()" method will require a new "true $yes" argument in the next major version of its parent class "Symfony\Component\Debug\Tests\Fixtures\ClassWithAnnotatedParameters", not defining it is deprecated.',
        ], $deprecations);
    }
@@ -309,7 +309,7 @@ class DebugClassLoaderTest extends TestCase
        set_error_handler(function ($type, $msg) use (&$deprecations) { $deprecations[] = $msg; });
        $e = error_reporting(E_USER_DEPRECATED);

-        class_exists('Test\\'.__NAMESPACE__.'\\UseTraitWithInternalMethod', true);
+        class_exists('Test\\'.UseTraitWithInternalMethod::class, true);

        error_reporting($e);
        restore_error_handler();
@@ -323,7 +323,7 @@ class DebugClassLoaderTest extends TestCase
        set_error_handler(function ($type, $msg) use (&$deprecations) { $deprecations[] = $msg; });
        $e = error_reporting(E_USER_DEPRECATED);

-        class_exists('Test\\'.__NAMESPACE__.'\\ExtendsVirtual', true);
+        class_exists('Test\\'.ExtendsVirtual::class, true);

        error_reporting($e);
        restore_error_handler();
@@ -349,7 +349,7 @@ class DebugClassLoaderTest extends TestCase
        set_error_handler(function ($type, $msg) use (&$deprecations) { $deprecations[] = $msg; });
        $e = error_reporting(E_USER_DEPRECATED);

-        class_exists('Test\\'.__NAMESPACE__.'\\ExtendsVirtualMagicCall', true);
+        class_exists('Test\\'.ExtendsVirtualMagicCall::class, true);

        error_reporting($e);
        restore_error_handler();
@@ -359,7 +359,7 @@ class DebugClassLoaderTest extends TestCase

    public function testEvaluatedCode()
    {
-        $this->assertTrue(class_exists(__NAMESPACE__.'\Fixtures\DefinitionInEvaluatedCode', true));
+        $this->assertTrue(class_exists(Fixtures\DefinitionInEvaluatedCode::class, true));
    }
 }

@@ -378,11 +378,11 @@ class ClassLoader
    {
        $fixtureDir = __DIR__.\DIRECTORY_SEPARATOR.'Fixtures'.\DIRECTORY_SEPARATOR;

-        if (__NAMESPACE__.'\TestingUnsilencing' === $class) {
+        if (TestingUnsilencing::class === $class) {
            eval('-- parse error --');
-        } elseif (__NAMESPACE__.'\TestingStacking' === $class) {
+        } elseif (TestingStacking::class === $class) {
            eval('namespace '.__NAMESPACE__.'; class TestingStacking { function foo() {} }');
-        } elseif (__NAMESPACE__.'\TestingCaseMismatch' === $class) {
+        } elseif (TestingCaseMismatch::class === $class) {
            eval('namespace '.__NAMESPACE__.'; class TestingCaseMisMatch {}');
        } elseif (__NAMESPACE__.'\Fixtures\Psr4CaseMismatch' === $class) {
            return $fixtureDir.'psr4'.\DIRECTORY_SEPARATOR.'Psr4CaseMismatch.php';
@@ -392,55 +392,55 @@ class ClassLoader
            return $fixtureDir.'notPsr0Bis.php';
        } elseif ('Symfony\Bridge\Debug\Tests\Fixtures\ExtendsDeprecatedParent' === $class) {
            eval('namespace Symfony\Bridge\Debug\Tests\Fixtures; class ExtendsDeprecatedParent extends \\'.__NAMESPACE__.'\Fixtures\DeprecatedClass {}');
-        } elseif ('Test\\'.__NAMESPACE__.'\DeprecatedParentClass' === $class) {
+        } elseif ('Test\\'.DeprecatedParentClass::class === $class) {
            eval('namespace Test\\'.__NAMESPACE__.'; class DeprecatedParentClass extends \\'.__NAMESPACE__.'\Fixtures\DeprecatedClass {}');
-        } elseif ('Test\\'.__NAMESPACE__.'\DeprecatedInterfaceClass' === $class) {
+        } elseif ('Test\\'.DeprecatedInterfaceClass::class === $class) {
            eval('namespace Test\\'.__NAMESPACE__.'; class DeprecatedInterfaceClass implements \\'.__NAMESPACE__.'\Fixtures\DeprecatedInterface {}');
-        } elseif ('Test\\'.__NAMESPACE__.'\NonDeprecatedInterfaceClass' === $class) {
+        } elseif ('Test\\'.NonDeprecatedInterfaceClass::class === $class) {
            eval('namespace Test\\'.__NAMESPACE__.'; class NonDeprecatedInterfaceClass implements \\'.__NAMESPACE__.'\Fixtures\NonDeprecatedInterface {}');
-        } elseif ('Test\\'.__NAMESPACE__.'\Float' === $class) {
+        } elseif ('Test\\'.Float::class === $class) {
            eval('namespace Test\\'.__NAMESPACE__.'; class Float {}');
-        } elseif (0 === strpos($class, 'Test\\'.__NAMESPACE__.'\ExtendsFinalClass')) {
+        } elseif (0 === strpos($class, 'Test\\'.ExtendsFinalClass::class)) {
            $classShortName = substr($class, strrpos($class, '\\') + 1);
            eval('namespace Test\\'.__NAMESPACE__.'; class '.$classShortName.' extends \\'.__NAMESPACE__.'\Fixtures\\'.substr($classShortName, 7).' {}');
-        } elseif ('Test\\'.__NAMESPACE__.'\ExtendsAnnotatedClass' === $class) {
+        } elseif ('Test\\'.ExtendsAnnotatedClass::class === $class) {
            eval('namespace Test\\'.__NAMESPACE__.'; class ExtendsAnnotatedClass extends \\'.__NAMESPACE__.'\Fixtures\AnnotatedClass {
                public function deprecatedMethod() { }
            }');
-        } elseif ('Test\\'.__NAMESPACE__.'\ExtendsInternals' === $class) {
+        } elseif ('Test\\'.ExtendsInternals::class === $class) {
            eval('namespace Test\\'.__NAMESPACE__.'; class ExtendsInternals extends ExtendsInternalsParent {
                use \\'.__NAMESPACE__.'\Fixtures\InternalTrait;

                public function internalMethod() { }
            }');
-        } elseif ('Test\\'.__NAMESPACE__.'\ExtendsInternalsParent' === $class) {
+        } elseif ('Test\\'.ExtendsInternalsParent::class === $class) {
            eval('namespace Test\\'.__NAMESPACE__.'; class ExtendsInternalsParent extends \\'.__NAMESPACE__.'\Fixtures\InternalClass implements \\'.__NAMESPACE__.'\Fixtures\InternalInterface { }');
-        } elseif ('Test\\'.__NAMESPACE__.'\UseTraitWithInternalMethod' === $class) {
+        } elseif ('Test\\'.UseTraitWithInternalMethod::class === $class) {
            eval('namespace Test\\'.__NAMESPACE__.'; class UseTraitWithInternalMethod { use \\'.__NAMESPACE__.'\Fixtures\TraitWithInternalMethod; }');
-        } elseif ('Test\\'.__NAMESPACE__.'\ExtendsVirtual' === $class) {
+        } elseif ('Test\\'.ExtendsVirtual::class === $class) {
            eval('namespace Test\\'.__NAMESPACE__.'; class ExtendsVirtual extends ExtendsVirtualParent implements \\'.__NAMESPACE__.'\Fixtures\VirtualSubInterface {
                public function ownClassMethod() { }
                public function classMethod() { }
                public function sameLineInterfaceMethodNoBraces() { }
            }');
-        } elseif ('Test\\'.__NAMESPACE__.'\ExtendsVirtualParent' === $class) {
+        } elseif ('Test\\'.ExtendsVirtualParent::class === $class) {
            eval('namespace Test\\'.__NAMESPACE__.'; class ExtendsVirtualParent extends ExtendsVirtualAbstract {
                public function ownParentMethod() { }
                public function traitMethod() { }
                public function sameLineInterfaceMethod() { }
                public function staticMethodNoBraces() { } // should be static
            }');
-        } elseif ('Test\\'.__NAMESPACE__.'\ExtendsVirtualAbstract' === $class) {
+        } elseif ('Test\\'.ExtendsVirtualAbstract::class === $class) {
            eval('namespace Test\\'.__NAMESPACE__.'; abstract class ExtendsVirtualAbstract extends ExtendsVirtualAbstractBase {
                public static function staticMethod() { }
                public function ownAbstractMethod() { }
                public function interfaceMethod() { }
            }');
-        } elseif ('Test\\'.__NAMESPACE__.'\ExtendsVirtualAbstractBase' === $class) {
+        } elseif ('Test\\'.ExtendsVirtualAbstractBase::class === $class) {
            eval('namespace Test\\'.__NAMESPACE__.'; abstract class ExtendsVirtualAbstractBase extends \\'.__NAMESPACE__.'\Fixtures\VirtualClass implements \\'.__NAMESPACE__.'\Fixtures\VirtualInterface {
                public function ownAbstractBaseMethod() { }
            }');
-        } elseif ('Test\\'.__NAMESPACE__.'\ExtendsVirtualMagicCall' === $class) {
+        } elseif ('Test\\'.ExtendsVirtualMagicCall::class === $class) {
            eval('namespace Test\\'.__NAMESPACE__.'; class ExtendsVirtualMagicCall extends \\'.__NAMESPACE__.'\Fixtures\VirtualClassMagicCall implements \\'.__NAMESPACE__.'\Fixtures\VirtualInterface {
            }');
        }
--- a/Tests/ErrorHandlerTest.php
+++ b/Tests/ErrorHandlerTest.php
@@ -12,10 +12,12 @@
 namespace Symfony\Component\Debug\Tests;

 use PHPUnit\Framework\TestCase;
+use Psr\Log\LoggerInterface;
 use Psr\Log\LogLevel;
 use Psr\Log\NullLogger;
 use Symfony\Component\Debug\BufferingLogger;
 use Symfony\Component\Debug\ErrorHandler;
+use Symfony\Component\Debug\Exception\ClassNotFoundException;
 use Symfony\Component\Debug\Exception\SilencedErrorContext;
 use Symfony\Component\Debug\Tests\Fixtures\ErrorHandlerThatUsesThePreviousOne;
 use Symfony\Component\Debug\Tests\Fixtures\LoggerThatSetAnErrorHandler;
@@ -25,6 +27,8 @@ use Symfony\Component\Debug\Tests\Fixtures\LoggerThatSetAnErrorHandler;
 *
 * @author Robert Schönthal <seroscho@googlemail.com>
 * @author Nicolas Grekas <p@tchwork.com>
+ *
+ * @group legacy
 */
 class ErrorHandlerTest extends TestCase
 {
@@ -33,7 +37,7 @@ class ErrorHandlerTest extends TestCase
        $handler = ErrorHandler::register();

        try {
-            $this->assertInstanceOf('Symfony\Component\Debug\ErrorHandler', $handler);
+            $this->assertInstanceOf(ErrorHandler::class, $handler);
            $this->assertSame($handler, ErrorHandler::register());

            $newHandler = new ErrorHandler();
@@ -70,15 +74,15 @@ class ErrorHandlerTest extends TestCase

    public function testErrorGetLast()
    {
+        $logger = $this->createMock(LoggerInterface::class);
        $handler = ErrorHandler::register();
-        $logger = $this->getMockBuilder('Psr\Log\LoggerInterface')->getMock();
        $handler->setDefaultLogger($logger);
-        $handler->screamAt(E_ALL);
+        $handler->screamAt(\E_ALL);

        try {
-            @trigger_error('Hello', E_USER_WARNING);
+            @trigger_error('Hello', \E_USER_WARNING);
            $expected = [
-                'type' => E_USER_WARNING,
+                'type' => \E_USER_WARNING,
                'message' => 'Hello',
                'file' => __FILE__,
                'line' => __LINE__ - 5,
@@ -101,9 +105,14 @@ class ErrorHandlerTest extends TestCase
            $this->fail('ErrorException expected');
        } catch (\ErrorException $exception) {
            // if an exception is thrown, the test passed
-            $this->assertEquals(E_NOTICE, $exception->getSeverity());
+            if (\PHP_VERSION_ID < 80000) {
+                $this->assertEquals(\E_NOTICE, $exception->getSeverity());
+                $this->assertMatchesRegularExpression('/^Notice: Undefined variable: (foo|bar)/', $exception->getMessage());
+            } else {
+                $this->assertEquals(\E_WARNING, $exception->getSeverity());
+                $this->assertMatchesRegularExpression('/^Warning: Undefined variable \$(foo|bar)/', $exception->getMessage());
+            }
            $this->assertEquals(__FILE__, $exception->getFile());
-            $this->assertRegExp('/^Notice: Undefined variable: (foo|bar)/', $exception->getMessage());

            $trace = $exception->getTrace();

@@ -133,7 +142,7 @@ class ErrorHandlerTest extends TestCase
        try {
            $handler = ErrorHandler::register();
            $handler->throwAt(3, true);
-            $this->assertEquals(3 | E_RECOVERABLE_ERROR | E_USER_ERROR, $handler->throwAt(0));
+            $this->assertEquals(3 | \E_RECOVERABLE_ERROR | \E_USER_ERROR, $handler->throwAt(0));
        } finally {
            restore_error_handler();
            restore_exception_handler();
@@ -143,29 +152,28 @@ class ErrorHandlerTest extends TestCase
    public function testDefaultLogger()
    {
        try {
+            $logger = $this->createMock(LoggerInterface::class);
            $handler = ErrorHandler::register();

-            $logger = $this->getMockBuilder('Psr\Log\LoggerInterface')->getMock();
-
-            $handler->setDefaultLogger($logger, E_NOTICE);
-            $handler->setDefaultLogger($logger, [E_USER_NOTICE => LogLevel::CRITICAL]);
+            $handler->setDefaultLogger($logger, \E_NOTICE);
+            $handler->setDefaultLogger($logger, [\E_USER_NOTICE => LogLevel::CRITICAL]);

            $loggers = [
-                E_DEPRECATED => [null, LogLevel::INFO],
-                E_USER_DEPRECATED => [null, LogLevel::INFO],
-                E_NOTICE => [$logger, LogLevel::WARNING],
-                E_USER_NOTICE => [$logger, LogLevel::CRITICAL],
-                E_STRICT => [null, LogLevel::WARNING],
-                E_WARNING => [null, LogLevel::WARNING],
-                E_USER_WARNING => [null, LogLevel::WARNING],
-                E_COMPILE_WARNING => [null, LogLevel::WARNING],
-                E_CORE_WARNING => [null, LogLevel::WARNING],
-                E_USER_ERROR => [null, LogLevel::CRITICAL],
-                E_RECOVERABLE_ERROR => [null, LogLevel::CRITICAL],
-                E_COMPILE_ERROR => [null, LogLevel::CRITICAL],
-                E_PARSE => [null, LogLevel::CRITICAL],
-                E_ERROR => [null, LogLevel::CRITICAL],
-                E_CORE_ERROR => [null, LogLevel::CRITICAL],
+                \E_DEPRECATED => [null, LogLevel::INFO],
+                \E_USER_DEPRECATED => [null, LogLevel::INFO],
+                \E_NOTICE => [$logger, LogLevel::WARNING],
+                \E_USER_NOTICE => [$logger, LogLevel::CRITICAL],
+                \E_STRICT => [null, LogLevel::WARNING],
+                \E_WARNING => [null, LogLevel::WARNING],
+                \E_USER_WARNING => [null, LogLevel::WARNING],
+                \E_COMPILE_WARNING => [null, LogLevel::WARNING],
+                \E_CORE_WARNING => [null, LogLevel::WARNING],
+                \E_USER_ERROR => [null, LogLevel::CRITICAL],
+                \E_RECOVERABLE_ERROR => [null, LogLevel::CRITICAL],
+                \E_COMPILE_ERROR => [null, LogLevel::CRITICAL],
+                \E_PARSE => [null, LogLevel::CRITICAL],
+                \E_ERROR => [null, LogLevel::CRITICAL],
+                \E_CORE_ERROR => [null, LogLevel::CRITICAL],
            ];
            $this->assertSame($loggers, $handler->setLoggers([]));
        } finally {
@@ -206,20 +214,20 @@ class ErrorHandlerTest extends TestCase
            restore_exception_handler();

            $handler = ErrorHandler::register();
-            $handler->throwAt(E_USER_DEPRECATED, true);
-            $this->assertFalse($handler->handleError(E_USER_DEPRECATED, 'foo', 'foo.php', 12, []));
+            $handler->throwAt(\E_USER_DEPRECATED, true);
+            $this->assertFalse($handler->handleError(\E_USER_DEPRECATED, 'foo', 'foo.php', 12, []));

            restore_error_handler();
            restore_exception_handler();

            $handler = ErrorHandler::register();
-            $handler->throwAt(E_DEPRECATED, true);
-            $this->assertFalse($handler->handleError(E_DEPRECATED, 'foo', 'foo.php', 12, []));
+            $handler->throwAt(\E_DEPRECATED, true);
+            $this->assertFalse($handler->handleError(\E_DEPRECATED, 'foo', 'foo.php', 12, []));

            restore_error_handler();
            restore_exception_handler();

-            $logger = $this->getMockBuilder('Psr\Log\LoggerInterface')->getMock();
+            $logger = $this->createMock(LoggerInterface::class);

            $warnArgCheck = function ($logLevel, $message, $context) {
                $this->assertEquals('info', $logLevel);
@@ -228,7 +236,7 @@ class ErrorHandlerTest extends TestCase
                $exception = $context['exception'];
                $this->assertInstanceOf(\ErrorException::class, $exception);
                $this->assertSame('User Deprecated: foo', $exception->getMessage());
-                $this->assertSame(E_USER_DEPRECATED, $exception->getSeverity());
+                $this->assertSame(\E_USER_DEPRECATED, $exception->getSeverity());
            };

            $logger
@@ -238,21 +246,27 @@ class ErrorHandlerTest extends TestCase
            ;

            $handler = ErrorHandler::register();
-            $handler->setDefaultLogger($logger, E_USER_DEPRECATED);
-            $this->assertTrue($handler->handleError(E_USER_DEPRECATED, 'foo', 'foo.php', 12, []));
+            $handler->setDefaultLogger($logger, \E_USER_DEPRECATED);
+            $this->assertTrue($handler->handleError(\E_USER_DEPRECATED, 'foo', 'foo.php', 12, []));

            restore_error_handler();
            restore_exception_handler();

-            $logger = $this->getMockBuilder('Psr\Log\LoggerInterface')->getMock();
+            $logger = $this->createMock(LoggerInterface::class);

            $line = null;
            $logArgCheck = function ($level, $message, $context) use (&$line) {
-                $this->assertEquals('Notice: Undefined variable: undefVar', $message);
                $this->assertArrayHasKey('exception', $context);
                $exception = $context['exception'];
+
+                if (\PHP_VERSION_ID < 80000) {
+                    $this->assertEquals('Notice: Undefined variable: undefVar', $message);
+                    $this->assertSame(\E_NOTICE, $exception->getSeverity());
+                } else {
+                    $this->assertEquals('Warning: Undefined variable $undefVar', $message);
+                    $this->assertSame(\E_WARNING, $exception->getSeverity());
+                }
                $this->assertInstanceOf(SilencedErrorContext::class, $exception);
-                $this->assertSame(E_NOTICE, $exception->getSeverity());
                $this->assertSame(__FILE__, $exception->getFile());
                $this->assertSame($line, $exception->getLine());
                $this->assertNotEmpty($exception->getTrace());
@@ -266,8 +280,13 @@ class ErrorHandlerTest extends TestCase
            ;

            $handler = ErrorHandler::register();
-            $handler->setDefaultLogger($logger, E_NOTICE);
-            $handler->screamAt(E_NOTICE);
+            if (\PHP_VERSION_ID < 80000) {
+                $handler->setDefaultLogger($logger, \E_NOTICE);
+                $handler->screamAt(\E_NOTICE);
+            } else {
+                $handler->setDefaultLogger($logger, \E_WARNING);
+                $handler->screamAt(\E_WARNING);
+            }
            unset($undefVar);
            $line = __LINE__ + 1;
            @$undefVar++;
@@ -284,6 +303,10 @@ class ErrorHandlerTest extends TestCase

    public function testHandleUserError()
    {
+        if (\PHP_VERSION_ID >= 70400) {
+            $this->markTestSkipped('PHP 7.4 allows __toString to throw exceptions');
+        }
+
        try {
            $handler = ErrorHandler::register();
            $handler->throwAt(0, true);
@@ -304,6 +327,26 @@ class ErrorHandlerTest extends TestCase
        }
    }

+    public function testHandleErrorWithAnonymousClass()
+    {
+        $handler = ErrorHandler::register();
+        $handler->throwAt(\E_USER_WARNING, true);
+        try {
+            $handler->handleError(\E_USER_WARNING, 'foo '.\get_class(new class() extends \stdClass {
+            }).' bar', 'foo.php', 12);
+            $this->fail('Exception expected.');
+        } catch (\ErrorException $e) {
+        } finally {
+            restore_error_handler();
+            restore_exception_handler();
+        }
+
+        $this->assertSame('User Warning: foo stdClass@anonymous bar', $e->getMessage());
+        $this->assertSame(\E_USER_WARNING, $e->getSeverity());
+        $this->assertSame('foo.php', $e->getFile());
+        $this->assertSame(12, $e->getLine());
+    }
+
    public function testHandleDeprecation()
    {
        $logArgCheck = function ($level, $message, $context) {
@@ -314,7 +357,7 @@ class ErrorHandlerTest extends TestCase
            $this->assertSame('User Deprecated: Foo deprecation', $exception->getMessage());
        };

-        $logger = $this->getMockBuilder('Psr\Log\LoggerInterface')->getMock();
+        $logger = $this->createMock(LoggerInterface::class);
        $logger
            ->expects($this->once())
            ->method('log')
@@ -323,20 +366,17 @@ class ErrorHandlerTest extends TestCase

        $handler = new ErrorHandler();
        $handler->setDefaultLogger($logger);
-        @$handler->handleError(E_USER_DEPRECATED, 'Foo deprecation', __FILE__, __LINE__, []);
-
-        restore_error_handler();
+        @$handler->handleError(\E_USER_DEPRECATED, 'Foo deprecation', __FILE__, __LINE__, []);
    }

    public function testHandleException()
    {
        try {
+            $logger = $this->createMock(LoggerInterface::class);
            $handler = ErrorHandler::register();

            $exception = new \Exception('foo');

-            $logger = $this->getMockBuilder('Psr\Log\LoggerInterface')->getMock();
-
            $logArgCheck = function ($level, $message, $context) {
                $this->assertSame('Uncaught Exception: foo', $message);
                $this->assertArrayHasKey('exception', $context);
@@ -349,7 +389,7 @@ class ErrorHandlerTest extends TestCase
                ->willReturnCallback($logArgCheck)
            ;

-            $handler->setDefaultLogger($logger, E_ERROR);
+            $handler->setDefaultLogger($logger, \E_ERROR);

            try {
                $handler->handleException($exception);
@@ -375,26 +415,26 @@ class ErrorHandlerTest extends TestCase
        $handler = new ErrorHandler($bootLogger);

        $loggers = [
-            E_DEPRECATED => [$bootLogger, LogLevel::INFO],
-            E_USER_DEPRECATED => [$bootLogger, LogLevel::INFO],
-            E_NOTICE => [$bootLogger, LogLevel::WARNING],
-            E_USER_NOTICE => [$bootLogger, LogLevel::WARNING],
-            E_STRICT => [$bootLogger, LogLevel::WARNING],
-            E_WARNING => [$bootLogger, LogLevel::WARNING],
-            E_USER_WARNING => [$bootLogger, LogLevel::WARNING],
-            E_COMPILE_WARNING => [$bootLogger, LogLevel::WARNING],
-            E_CORE_WARNING => [$bootLogger, LogLevel::WARNING],
-            E_USER_ERROR => [$bootLogger, LogLevel::CRITICAL],
-            E_RECOVERABLE_ERROR => [$bootLogger, LogLevel::CRITICAL],
-            E_COMPILE_ERROR => [$bootLogger, LogLevel::CRITICAL],
-            E_PARSE => [$bootLogger, LogLevel::CRITICAL],
-            E_ERROR => [$bootLogger, LogLevel::CRITICAL],
-            E_CORE_ERROR => [$bootLogger, LogLevel::CRITICAL],
+            \E_DEPRECATED => [$bootLogger, LogLevel::INFO],
+            \E_USER_DEPRECATED => [$bootLogger, LogLevel::INFO],
+            \E_NOTICE => [$bootLogger, LogLevel::WARNING],
+            \E_USER_NOTICE => [$bootLogger, LogLevel::WARNING],
+            \E_STRICT => [$bootLogger, LogLevel::WARNING],
+            \E_WARNING => [$bootLogger, LogLevel::WARNING],
+            \E_USER_WARNING => [$bootLogger, LogLevel::WARNING],
+            \E_COMPILE_WARNING => [$bootLogger, LogLevel::WARNING],
+            \E_CORE_WARNING => [$bootLogger, LogLevel::WARNING],
+            \E_USER_ERROR => [$bootLogger, LogLevel::CRITICAL],
+            \E_RECOVERABLE_ERROR => [$bootLogger, LogLevel::CRITICAL],
+            \E_COMPILE_ERROR => [$bootLogger, LogLevel::CRITICAL],
+            \E_PARSE => [$bootLogger, LogLevel::CRITICAL],
+            \E_ERROR => [$bootLogger, LogLevel::CRITICAL],
+            \E_CORE_ERROR => [$bootLogger, LogLevel::CRITICAL],
        ];

        $this->assertSame($loggers, $handler->setLoggers([]));

-        $handler->handleError(E_DEPRECATED, 'Foo message', __FILE__, 123, []);
+        $handler->handleError(\E_DEPRECATED, 'Foo message', __FILE__, 123, []);

        $logs = $bootLogger->cleanLogs();

@@ -408,16 +448,16 @@ class ErrorHandlerTest extends TestCase
        $this->assertSame('Deprecated: Foo message', $exception->getMessage());
        $this->assertSame(__FILE__, $exception->getFile());
        $this->assertSame(123, $exception->getLine());
-        $this->assertSame(E_DEPRECATED, $exception->getSeverity());
+        $this->assertSame(\E_DEPRECATED, $exception->getSeverity());

        $bootLogger->log(LogLevel::WARNING, 'Foo message', ['exception' => $exception]);

-        $mockLogger = $this->getMockBuilder('Psr\Log\LoggerInterface')->getMock();
+        $mockLogger = $this->createMock(LoggerInterface::class);
        $mockLogger->expects($this->once())
            ->method('log')
            ->with(LogLevel::WARNING, 'Foo message', ['exception' => $exception]);

-        $handler->setLoggers([E_DEPRECATED => [$mockLogger, LogLevel::WARNING]]);
+        $handler->setLoggers([\E_DEPRECATED => [$mockLogger, LogLevel::WARNING]]);
    }

    public function testSettingLoggerWhenExceptionIsBuffered()
@@ -427,7 +467,7 @@ class ErrorHandlerTest extends TestCase

        $exception = new \Exception('Foo message');

-        $mockLogger = $this->getMockBuilder('Psr\Log\LoggerInterface')->getMock();
+        $mockLogger = $this->createMock(LoggerInterface::class);
        $mockLogger->expects($this->once())
            ->method('log')
            ->with(LogLevel::CRITICAL, 'Uncaught Exception: Foo message', ['exception' => $exception]);
@@ -442,17 +482,16 @@ class ErrorHandlerTest extends TestCase
    public function testHandleFatalError()
    {
        try {
+            $logger = $this->createMock(LoggerInterface::class);
            $handler = ErrorHandler::register();

            $error = [
-                'type' => E_PARSE,
+                'type' => \E_PARSE,
                'message' => 'foo',
                'file' => 'bar',
                'line' => 123,
            ];

-            $logger = $this->getMockBuilder('Psr\Log\LoggerInterface')->getMock();
-
            $logArgCheck = function ($level, $message, $context) {
                $this->assertEquals('Fatal Parse Error: foo', $message);
                $this->assertArrayHasKey('exception', $context);
@@ -465,7 +504,7 @@ class ErrorHandlerTest extends TestCase
                ->willReturnCallback($logArgCheck)
            ;

-            $handler->setDefaultLogger($logger, E_PARSE);
+            $handler->setDefaultLogger($logger, \E_PARSE);

            $handler->handleFatalError($error);

@@ -490,15 +529,13 @@ class ErrorHandlerTest extends TestCase

        $handler->handleException($exception);

-        $this->assertInstanceOf('Symfony\Component\Debug\Exception\ClassNotFoundException', $args[0]);
+        $this->assertInstanceOf(ClassNotFoundException::class, $args[0]);
        $this->assertStringStartsWith("Attempted to load class \"IReallyReallyDoNotExistAnywhereInTheRepositoryISwear\" from the global namespace.\nDid you forget a \"use\" statement", $args[0]->getMessage());
    }

-    /**
-     * @expectedException \Exception
-     */
    public function testCustomExceptionHandler()
    {
+        $this->expectException(\Exception::class);
        $handler = new ErrorHandler();
        $handler->setExceptionHandler(function ($e) use ($handler) {
            $handler->handleException($e);
@@ -526,8 +563,8 @@ class ErrorHandlerTest extends TestCase
                $handler = ErrorHandlerThatUsesThePreviousOne::register();
            }

-            @trigger_error('foo', E_USER_DEPRECATED);
-            @trigger_error('bar', E_USER_DEPRECATED);
+            @trigger_error('foo', \E_USER_DEPRECATED);
+            @trigger_error('bar', \E_USER_DEPRECATED);

            $this->assertSame([$handler, 'handleError'], set_error_handler('var_dump'));

--- a/Tests/Exception/FlattenExceptionTest.php
+++ b/Tests/Exception/FlattenExceptionTest.php
@@ -30,6 +30,9 @@ use Symfony\Component\HttpKernel\Exception\TooManyRequestsHttpException;
 use Symfony\Component\HttpKernel\Exception\UnauthorizedHttpException;
 use Symfony\Component\HttpKernel\Exception\UnsupportedMediaTypeHttpException;

+/**
+ * @group legacy
+ */
 class FlattenExceptionTest extends TestCase
 {
    public function testStatusCode()
@@ -171,9 +174,9 @@ class FlattenExceptionTest extends TestCase

        $flattened = FlattenException::create($exception)->getPrevious();

-        $this->assertEquals($flattened->getMessage(), 'Oh noes!', 'The message is copied from the original exception.');
-        $this->assertEquals($flattened->getCode(), 42, 'The code is copied from the original exception.');
-        $this->assertEquals($flattened->getClass(), 'ParseError', 'The class is set to the class of the original exception');
+        $this->assertEquals('Oh noes!', $flattened->getMessage(), 'The message is copied from the original exception.');
+        $this->assertEquals(42, $flattened->getCode(), 'The code is copied from the original exception.');
+        $this->assertEquals('ParseError', $flattened->getClass(), 'The class is set to the class of the original exception');
    }

    /**
@@ -237,6 +240,10 @@ class FlattenExceptionTest extends TestCase

    public function testArguments()
    {
+        if (\PHP_VERSION_ID >= 70400) {
+            $this->markTestSkipped('PHP 7.4 removes arguments from exception traces.');
+        }
+
        $dh = opendir(__DIR__);
        $fh = tmpfile();

@@ -258,8 +265,8 @@ class FlattenExceptionTest extends TestCase
            0.0,
            '0',
            '',
-            INF,
-            NAN,
+            \INF,
+            \NAN,
        ]);

        $flattened = FlattenException::create($exception);
@@ -279,7 +286,7 @@ class FlattenExceptionTest extends TestCase

        $args = $array[$i++];
        $this->assertSame($args[0], 'object');
-        $this->assertTrue('Closure' === $args[1] || is_subclass_of($args[1], '\Closure'), 'Expect object class name to be Closure or a subclass of Closure.');
+        $this->assertTrue('Closure' === $args[1] || is_subclass_of($args[1], \Closure::class), 'Expect object class name to be Closure or a subclass of Closure.');

        $this->assertSame(['array', [['integer', 1], ['integer', 2]]], $array[$i++]);
        $this->assertSame(['array', ['foo' => ['integer', 123]]], $array[$i++]);
@@ -290,26 +297,34 @@ class FlattenExceptionTest extends TestCase
        $this->assertSame(['float', 0.0], $array[$i++]);
        $this->assertSame(['string', '0'], $array[$i++]);
        $this->assertSame(['string', ''], $array[$i++]);
-        $this->assertSame(['float', INF], $array[$i++]);
+        $this->assertSame(['float', \INF], $array[$i++]);

        // assertEquals() does not like NAN values.
-        $this->assertEquals($array[$i][0], 'float');
-        $this->assertTrue(is_nan($array[$i++][1]));
+        $this->assertEquals('float', $array[$i][0]);
+        $this->assertNan($array[$i][1]);
    }

    public function testRecursionInArguments()
    {
+        if (\PHP_VERSION_ID >= 70400) {
+            $this->markTestSkipped('PHP 7.4 removes arguments from exception traces.');
+        }
+
        $a = null;
        $a = ['foo', [2, &$a]];
        $exception = $this->createException($a);

        $flattened = FlattenException::create($exception);
        $trace = $flattened->getTrace();
-        $this->assertContains('*DEEP NESTED ARRAY*', serialize($trace));
+        $this->assertStringContainsString('*DEEP NESTED ARRAY*', serialize($trace));
    }

    public function testTooBigArray()
    {
+        if (\PHP_VERSION_ID >= 70400) {
+            $this->markTestSkipped('PHP 7.4 removes arguments from exception traces.');
+        }
+
        $a = [];
        for ($i = 0; $i < 20; ++$i) {
            for ($j = 0; $j < 50; ++$j) {
@@ -329,8 +344,8 @@ class FlattenExceptionTest extends TestCase

        $serializeTrace = serialize($trace);

-        $this->assertContains('*SKIPPED over 10000 entries*', $serializeTrace);
-        $this->assertNotContains('*value1*', $serializeTrace);
+        $this->assertStringContainsString('*SKIPPED over 10000 entries*', $serializeTrace);
+        $this->assertStringNotContainsString('*value1*', $serializeTrace);
    }

    public function testAnonymousClass()
@@ -340,6 +355,11 @@ class FlattenExceptionTest extends TestCase

        $this->assertSame('RuntimeException@anonymous', $flattened->getClass());

+        $flattened->setClass(\get_class(new class('Oops') extends NotFoundHttpException {
+        }));
+
+        $this->assertSame('Symfony\Component\HttpKernel\Exception\NotFoundHttpException@anonymous', $flattened->getClass());
+
        $flattened = FlattenException::create(new \Exception(sprintf('Class "%s" blah.', \get_class(new class() extends \RuntimeException {
        }))));

--- a/Tests/ExceptionHandlerTest.php
+++ b/Tests/ExceptionHandlerTest.php
@@ -19,18 +19,24 @@ use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;

 require_once __DIR__.'/HeaderMock.php';

+/**
+ * @group legacy
+ */
 class ExceptionHandlerTest extends TestCase
 {
-    protected function setUp()
+    protected function setUp(): void
    {
        testHeader();
    }

-    protected function tearDown()
+    protected function tearDown(): void
    {
        testHeader();
    }

+    /**
+     * @group legacy
+     */
    public function testDebug()
    {
        $handler = new ExceptionHandler(false);
@@ -39,8 +45,8 @@ class ExceptionHandlerTest extends TestCase
        $handler->sendPhpResponse(new \RuntimeException('Foo'));
        $response = ob_get_clean();

-        $this->assertContains('Whoops, looks like something went wrong.', $response);
-        $this->assertNotContains('<div class="trace trace-as-html">', $response);
+        $this->assertStringContainsString('Whoops, looks like something went wrong.', $response);
+        $this->assertStringNotContainsString('<div class="trace trace-as-html">', $response);

        $handler = new ExceptionHandler(true);

@@ -48,8 +54,8 @@ class ExceptionHandlerTest extends TestCase
        $handler->sendPhpResponse(new \RuntimeException('Foo'));
        $response = ob_get_clean();

-        $this->assertContains('<h1 class="break-long-words exception-message">Foo</h1>', $response);
-        $this->assertContains('<div class="trace trace-as-html">', $response);
+        $this->assertStringContainsString('<h1 class="break-long-words exception-message">Foo</h1>', $response);
+        $this->assertStringContainsString('<div class="trace trace-as-html">', $response);

        // taken from https://www.owasp.org/index.php/Cross-site_Scripting_(XSS)
        $htmlWithXss = '<body onload=alert(\'test1\')> <b onmouseover=alert(\'Wufff!\')>click me!</b> <img src="j&#X41vascript:alert(\'test2\')"> <meta http-equiv="refresh"
@@ -58,7 +64,7 @@ content="0;url=data:text/html;base64,PHNjcmlwdD5hbGVydCgndGVzdDMnKTwvc2NyaXB0Pg"
        $handler->sendPhpResponse(new \RuntimeException($htmlWithXss));
        $response = ob_get_clean();

-        $this->assertContains(sprintf('<h1 class="break-long-words exception-message">%s</h1>', htmlspecialchars($htmlWithXss, ENT_COMPAT | ENT_SUBSTITUTE, 'UTF-8')), $response);
+        $this->assertStringContainsString(sprintf('<h1 class="break-long-words exception-message">%s</h1>', htmlspecialchars($htmlWithXss, \ENT_COMPAT | \ENT_SUBSTITUTE, 'UTF-8')), $response);
    }

    public function testStatusCode()
@@ -69,7 +75,7 @@ content="0;url=data:text/html;base64,PHNjcmlwdD5hbGVydCgndGVzdDMnKTwvc2NyaXB0Pg"
        $handler->sendPhpResponse(new NotFoundHttpException('Foo'));
        $response = ob_get_clean();

-        $this->assertContains('Sorry, the page you are looking for could not be found.', $response);
+        $this->assertStringContainsString('Sorry, the page you are looking for could not be found.', $response);

        $expectedHeaders = [
            ['HTTP/1.0 404', true, null],
@@ -85,7 +91,7 @@ content="0;url=data:text/html;base64,PHNjcmlwdD5hbGVydCgndGVzdDMnKTwvc2NyaXB0Pg"

        ob_start();
        $handler->sendPhpResponse(new MethodNotAllowedHttpException(['POST']));
-        $response = ob_get_clean();
+        ob_get_clean();

        $expectedHeaders = [
            ['HTTP/1.0 405', true, null],
@@ -108,35 +114,65 @@ content="0;url=data:text/html;base64,PHNjcmlwdD5hbGVydCgndGVzdDMnKTwvc2NyaXB0Pg"

    public function testHandle()
    {
-        $exception = new \Exception('foo');
+        $handler = new ExceptionHandler(true);
+        ob_start();

-        $handler = $this->getMockBuilder('Symfony\Component\Debug\ExceptionHandler')->setMethods(['sendPhpResponse'])->getMock();
-        $handler
-            ->expects($this->exactly(2))
-            ->method('sendPhpResponse');
+        $handler->handle(new \Exception('foo'));

-        $handler->handle($exception);
+        $this->assertThatTheExceptionWasOutput(ob_get_clean(), \Exception::class, 'Exception', 'foo');
+    }

-        $handler->setHandler(function ($e) use ($exception) {
-            $this->assertSame($exception, $e);
+    public function testHandleWithACustomHandlerThatOutputsSomething()
+    {
+        $handler = new ExceptionHandler(true);
+        ob_start();
+        $handler->setHandler(function () {
+            echo 'ccc';
        });

-        $handler->handle($exception);
+        $handler->handle(new \Exception());
+        ob_end_flush(); // Necessary because of this PHP bug : https://bugs.php.net/76563
+        $this->assertSame('ccc', ob_get_clean());
+    }
+
+    public function testHandleWithACustomHandlerThatOutputsNothing()
+    {
+        $handler = new ExceptionHandler(true);
+        $handler->setHandler(function () {});
+
+        $handler->handle(new \Exception('ccc'));
+
+        $this->assertThatTheExceptionWasOutput(ob_get_clean(), \Exception::class, 'Exception', 'ccc');
+    }
+
+    public function testHandleWithACustomHandlerThatFails()
+    {
+        $handler = new ExceptionHandler(true);
+        $handler->setHandler(function () {
+            throw new \RuntimeException();
+        });
+
+        $handler->handle(new \Exception('ccc'));
+
+        $this->assertThatTheExceptionWasOutput(ob_get_clean(), \Exception::class, 'Exception', 'ccc');
    }

    public function testHandleOutOfMemoryException()
    {
-        $exception = new OutOfMemoryException('foo', 0, E_ERROR, __FILE__, __LINE__);
-
-        $handler = $this->getMockBuilder('Symfony\Component\Debug\ExceptionHandler')->setMethods(['sendPhpResponse'])->getMock();
-        $handler
-            ->expects($this->once())
-            ->method('sendPhpResponse');
-
-        $handler->setHandler(function ($e) {
+        $handler = new ExceptionHandler(true);
+        ob_start();
+        $handler->setHandler(function () {
            $this->fail('OutOfMemoryException should bypass the handler');
        });

-        $handler->handle($exception);
+        $handler->handle(new OutOfMemoryException('foo', 0, \E_ERROR, __FILE__, __LINE__));
+
+        $this->assertThatTheExceptionWasOutput(ob_get_clean(), OutOfMemoryException::class, 'OutOfMemoryException', 'foo');
+    }
+
+    private function assertThatTheExceptionWasOutput($content, $expectedClass, $expectedTitle, $expectedMessage)
+    {
+        $this->assertStringContainsString(sprintf('<span class="exception_title"><abbr title="%s">%s</abbr></span>', $expectedClass, $expectedTitle), $content);
+        $this->assertStringContainsString(sprintf('<p class="break-long-words trace-message">%s</p>', $expectedMessage), $content);
    }
 }
--- a/Tests/FatalErrorHandler/ClassNotFoundFatalErrorHandlerTest.php
+++ b/Tests/FatalErrorHandler/ClassNotFoundFatalErrorHandlerTest.php
@@ -14,12 +14,16 @@ namespace Symfony\Component\Debug\Tests\FatalErrorHandler;
 use Composer\Autoload\ClassLoader as ComposerClassLoader;
 use PHPUnit\Framework\TestCase;
 use Symfony\Component\Debug\DebugClassLoader;
+use Symfony\Component\Debug\Exception\ClassNotFoundException;
 use Symfony\Component\Debug\Exception\FatalErrorException;
 use Symfony\Component\Debug\FatalErrorHandler\ClassNotFoundFatalErrorHandler;

+/**
+ * @group legacy
+ */
 class ClassNotFoundFatalErrorHandlerTest extends TestCase
 {
-    public static function setUpBeforeClass()
+    public static function setUpBeforeClass(): void
    {
        foreach (spl_autoload_functions() as $function) {
            if (!\is_array($function)) {
@@ -29,10 +33,14 @@ class ClassNotFoundFatalErrorHandlerTest extends TestCase
            // get class loaders wrapped by DebugClassLoader
            if ($function[0] instanceof DebugClassLoader) {
                $function = $function[0]->getClassLoader();
+
+                if (!\is_array($function)) {
+                    continue;
+                }
            }

            if ($function[0] instanceof ComposerClassLoader) {
-                $function[0]->add('Symfony_Component_Debug_Tests_Fixtures', \dirname(\dirname(\dirname(\dirname(\dirname(__DIR__))))));
+                $function[0]->add('Symfony_Component_Debug_Tests_Fixtures', \dirname(__DIR__, 5));
                break;
            }
        }
@@ -60,8 +68,8 @@ class ClassNotFoundFatalErrorHandlerTest extends TestCase
            array_map('spl_autoload_register', $autoloaders);
        }

-        $this->assertInstanceOf('Symfony\Component\Debug\Exception\ClassNotFoundException', $exception);
-        $this->assertSame($translatedMessage, $exception->getMessage());
+        $this->assertInstanceOf(ClassNotFoundException::class, $exception);
+        $this->assertMatchesRegularExpression($translatedMessage, $exception->getMessage());
        $this->assertSame($error['type'], $exception->getSeverity());
        $this->assertSame($error['file'], $exception->getFile());
        $this->assertSame($error['line'], $exception->getLine());
@@ -71,10 +79,20 @@ class ClassNotFoundFatalErrorHandlerTest extends TestCase
    {
        $autoloader = new ComposerClassLoader();
        $autoloader->add('Symfony\Component\Debug\Exception\\', realpath(__DIR__.'/../../Exception'));
+        $autoloader->add('Symfony_Component_Debug_Tests_Fixtures', realpath(__DIR__.'/../../Tests/Fixtures'));

        $debugClassLoader = new DebugClassLoader([$autoloader, 'loadClass']);

        return [
+            [
+                [
+                    'type' => 1,
+                    'line' => 12,
+                    'file' => 'foo.php',
+                    'message' => 'Class "WhizBangFactory" not found',
+                ],
+                "/^Attempted to load class \"WhizBangFactory\" from the global namespace.\nDid you forget a \"use\" statement\?$/",
+            ],
            [
                [
                    'type' => 1,
@@ -82,7 +100,7 @@ class ClassNotFoundFatalErrorHandlerTest extends TestCase
                    'file' => 'foo.php',
                    'message' => 'Class \'WhizBangFactory\' not found',
                ],
-                "Attempted to load class \"WhizBangFactory\" from the global namespace.\nDid you forget a \"use\" statement?",
+                "/^Attempted to load class \"WhizBangFactory\" from the global namespace.\nDid you forget a \"use\" statement\?$/",
            ],
            [
                [
@@ -91,7 +109,34 @@ class ClassNotFoundFatalErrorHandlerTest extends TestCase
                    'file' => 'foo.php',
                    'message' => 'Class \'Foo\\Bar\\WhizBangFactory\' not found',
                ],
-                "Attempted to load class \"WhizBangFactory\" from namespace \"Foo\\Bar\".\nDid you forget a \"use\" statement for another namespace?",
+                "/^Attempted to load class \"WhizBangFactory\" from namespace \"Foo\\\\Bar\".\nDid you forget a \"use\" statement for another namespace\?$/",
+            ],
+            [
+                [
+                    'type' => 1,
+                    'line' => 12,
+                    'file' => 'foo.php',
+                    'message' => 'Class "Foo\\Bar\\WhizBangFactory" not found',
+                ],
+                "/^Attempted to load class \"WhizBangFactory\" from namespace \"Foo\\\\Bar\".\nDid you forget a \"use\" statement for another namespace\?$/",
+            ],
+            [
+                [
+                    'type' => 1,
+                    'line' => 12,
+                    'file' => 'foo.php',
+                    'message' => 'Interface "Foo\\Bar\\WhizBangInterface" not found',
+                ],
+                "/^Attempted to load interface \"WhizBangInterface\" from namespace \"Foo\\\\Bar\".\nDid you forget a \"use\" statement for another namespace\?$/",
+            ],
+            [
+                [
+                    'type' => 1,
+                    'line' => 12,
+                    'file' => 'foo.php',
+                    'message' => 'Trait "Foo\\Bar\\WhizBangTrait" not found',
+                ],
+                "/^Attempted to load trait \"WhizBangTrait\" from namespace \"Foo\\\\Bar\".\nDid you forget a \"use\" statement for another namespace\?$/",
            ],
            [
                [
@@ -100,7 +145,8 @@ class ClassNotFoundFatalErrorHandlerTest extends TestCase
                    'file' => 'foo.php',
                    'message' => 'Class \'UndefinedFunctionException\' not found',
                ],
-                "Attempted to load class \"UndefinedFunctionException\" from the global namespace.\nDid you forget a \"use\" statement for \"Symfony\Component\Debug\Exception\UndefinedFunctionException\"?",
+                "/^Attempted to load class \"UndefinedFunctionException\" from the global namespace.\nDid you forget a \"use\" statement for .*\"Symfony\\\\Component\\\\Debug\\\\Exception\\\\UndefinedFunctionException\"\?$/",
+                [$debugClassLoader, 'loadClass'],
            ],
            [
                [
@@ -109,35 +155,7 @@ class ClassNotFoundFatalErrorHandlerTest extends TestCase
                    'file' => 'foo.php',
                    'message' => 'Class \'PEARClass\' not found',
                ],
-                "Attempted to load class \"PEARClass\" from the global namespace.\nDid you forget a \"use\" statement for \"Symfony_Component_Debug_Tests_Fixtures_PEARClass\"?",
-            ],
-            [
-                [
-                    'type' => 1,
-                    'line' => 12,
-                    'file' => 'foo.php',
-                    'message' => 'Class \'Foo\\Bar\\UndefinedFunctionException\' not found',
-                ],
-                "Attempted to load class \"UndefinedFunctionException\" from namespace \"Foo\Bar\".\nDid you forget a \"use\" statement for \"Symfony\Component\Debug\Exception\UndefinedFunctionException\"?",
-            ],
-            [
-                [
-                    'type' => 1,
-                    'line' => 12,
-                    'file' => 'foo.php',
-                    'message' => 'Class \'Foo\\Bar\\UndefinedFunctionException\' not found',
-                ],
-                "Attempted to load class \"UndefinedFunctionException\" from namespace \"Foo\Bar\".\nDid you forget a \"use\" statement for \"Symfony\Component\Debug\Exception\UndefinedFunctionException\"?",
-                [$autoloader, 'loadClass'],
-            ],
-            [
-                [
-                    'type' => 1,
-                    'line' => 12,
-                    'file' => 'foo.php',
-                    'message' => 'Class \'Foo\\Bar\\UndefinedFunctionException\' not found',
-                ],
-                "Attempted to load class \"UndefinedFunctionException\" from namespace \"Foo\Bar\".\nDid you forget a \"use\" statement for \"Symfony\Component\Debug\Exception\UndefinedFunctionException\"?",
+                "/^Attempted to load class \"PEARClass\" from the global namespace.\nDid you forget a \"use\" statement for \"Symfony_Component_Debug_Tests_Fixtures_PEARClass\"\?$/",
                [$debugClassLoader, 'loadClass'],
            ],
            [
@@ -147,7 +165,37 @@ class ClassNotFoundFatalErrorHandlerTest extends TestCase
                    'file' => 'foo.php',
                    'message' => 'Class \'Foo\\Bar\\UndefinedFunctionException\' not found',
                ],
-                "Attempted to load class \"UndefinedFunctionException\" from namespace \"Foo\\Bar\".\nDid you forget a \"use\" statement for another namespace?",
+                "/^Attempted to load class \"UndefinedFunctionException\" from namespace \"Foo\\\\Bar\".\nDid you forget a \"use\" statement for .*\"Symfony\\\\Component\\\\Debug\\\\Exception\\\\UndefinedFunctionException\"\?$/",
+                [$debugClassLoader, 'loadClass'],
+            ],
+            [
+                [
+                    'type' => 1,
+                    'line' => 12,
+                    'file' => 'foo.php',
+                    'message' => 'Class \'Foo\\Bar\\UndefinedFunctionException\' not found',
+                ],
+                "/^Attempted to load class \"UndefinedFunctionException\" from namespace \"Foo\\\\Bar\".\nDid you forget a \"use\" statement for \"Symfony\\\\Component\\\\Debug\\\\Exception\\\\UndefinedFunctionException\"\?$/",
+                [$autoloader, 'loadClass'],
+            ],
+            [
+                [
+                    'type' => 1,
+                    'line' => 12,
+                    'file' => 'foo.php',
+                    'message' => 'Class \'Foo\\Bar\\UndefinedFunctionException\' not found',
+                ],
+                "/^Attempted to load class \"UndefinedFunctionException\" from namespace \"Foo\\\\Bar\".\nDid you forget a \"use\" statement for \"Symfony\\\\Component\\\\Debug\\\\Exception\\\\UndefinedFunctionException\"\?/",
+                [$debugClassLoader, 'loadClass'],
+            ],
+            [
+                [
+                    'type' => 1,
+                    'line' => 12,
+                    'file' => 'foo.php',
+                    'message' => 'Class \'Foo\\Bar\\UndefinedFunctionException\' not found',
+                ],
+                "/^Attempted to load class \"UndefinedFunctionException\" from namespace \"Foo\\\\Bar\".\nDid you forget a \"use\" statement for another namespace\?$/",
                function ($className) { /* do nothing here */ },
            ],
        ];
@@ -171,6 +219,6 @@ class ClassNotFoundFatalErrorHandlerTest extends TestCase
        $handler = new ClassNotFoundFatalErrorHandler();
        $exception = $handler->handleError($error, new FatalErrorException('', 0, $error['type'], $error['file'], $error['line']));

-        $this->assertInstanceOf('Symfony\Component\Debug\Exception\ClassNotFoundException', $exception);
+        $this->assertInstanceOf(ClassNotFoundException::class, $exception);
    }
 }
--- a/Tests/FatalErrorHandler/UndefinedFunctionFatalErrorHandlerTest.php
+++ b/Tests/FatalErrorHandler/UndefinedFunctionFatalErrorHandlerTest.php
@@ -13,8 +13,12 @@ namespace Symfony\Component\Debug\Tests\FatalErrorHandler;

 use PHPUnit\Framework\TestCase;
 use Symfony\Component\Debug\Exception\FatalErrorException;
+use Symfony\Component\Debug\Exception\UndefinedFunctionException;
 use Symfony\Component\Debug\FatalErrorHandler\UndefinedFunctionFatalErrorHandler;

+/**
+ * @group legacy
+ */
 class UndefinedFunctionFatalErrorHandlerTest extends TestCase
 {
    /**
@@ -25,7 +29,7 @@ class UndefinedFunctionFatalErrorHandlerTest extends TestCase
        $handler = new UndefinedFunctionFatalErrorHandler();
        $exception = $handler->handleError($error, new FatalErrorException('', 0, $error['type'], $error['file'], $error['line']));

-        $this->assertInstanceOf('Symfony\Component\Debug\Exception\UndefinedFunctionException', $exception);
+        $this->assertInstanceOf(UndefinedFunctionException::class, $exception);
        // class names are case insensitive and PHP do not return the same
        $this->assertSame(strtolower($translatedMessage), strtolower($exception->getMessage()));
        $this->assertSame($error['type'], $exception->getSeverity());
--- a/Tests/FatalErrorHandler/UndefinedMethodFatalErrorHandlerTest.php
+++ b/Tests/FatalErrorHandler/UndefinedMethodFatalErrorHandlerTest.php
@@ -13,8 +13,12 @@ namespace Symfony\Component\Debug\Tests\FatalErrorHandler;

 use PHPUnit\Framework\TestCase;
 use Symfony\Component\Debug\Exception\FatalErrorException;
+use Symfony\Component\Debug\Exception\UndefinedMethodException;
 use Symfony\Component\Debug\FatalErrorHandler\UndefinedMethodFatalErrorHandler;

+/**
+ * @group legacy
+ */
 class UndefinedMethodFatalErrorHandlerTest extends TestCase
 {
    /**
@@ -25,7 +29,7 @@ class UndefinedMethodFatalErrorHandlerTest extends TestCase
        $handler = new UndefinedMethodFatalErrorHandler();
        $exception = $handler->handleError($error, new FatalErrorException('', 0, $error['type'], $error['file'], $error['line']));

-        $this->assertInstanceOf('Symfony\Component\Debug\Exception\UndefinedMethodException', $exception);
+        $this->assertInstanceOf(UndefinedMethodException::class, $exception);
        $this->assertSame($translatedMessage, $exception->getMessage());
        $this->assertSame($error['type'], $exception->getSeverity());
        $this->assertSame($error['file'], $exception->getFile());
@@ -44,6 +48,15 @@ class UndefinedMethodFatalErrorHandlerTest extends TestCase
                ],
                'Attempted to call an undefined method named "what" of class "SplObjectStorage".',
            ],
+            [
+                [
+                    'type' => 1,
+                    'line' => 12,
+                    'file' => 'foo.php',
+                    'message' => 'Call to undefined method SplObjectStorage::()',
+                ],
+                'Attempted to call an undefined method named "" of class "SplObjectStorage".',
+            ],
            [
                [
                    'type' => 1,
--- a/Tests/Fixtures/ErrorHandlerThatUsesThePreviousOne.php
+++ b/Tests/Fixtures/ErrorHandlerThatUsesThePreviousOne.php
@@ -15,8 +15,8 @@ class ErrorHandlerThatUsesThePreviousOne
        return $handler;
    }

-    public function handleError($type, $message, $file, $line, $context)
+    public function handleError()
    {
-        return \call_user_func(self::$previous, $type, $message, $file, $line, $context);
+        return \call_user_func_array(self::$previous, \func_get_args());
    }
 }
--- a/Tests/Fixtures/FinalClasses.php
+++ b/Tests/Fixtures/FinalClasses.php
@@ -41,7 +41,6 @@ class FinalClass4
 /**
 * @author John Doe
 *
- *
 * @final multiline
 * comment
 */
--- a/Tests/Fixtures/LoggerThatSetAnErrorHandler.php
+++ b/Tests/Fixtures/LoggerThatSetAnErrorHandler.php
@@ -6,7 +6,7 @@ use Symfony\Component\Debug\BufferingLogger;

 class LoggerThatSetAnErrorHandler extends BufferingLogger
 {
-    public function log($level, $message, array $context = [])
+    public function log($level, $message, array $context = []): void
    {
        set_error_handler('is_string');
        parent::log($level, $message, $context);
--- a/Tests/MockExceptionHandler.php
+++ b/Tests/MockExceptionHandler.php
@@ -1,24 +0,0 @@
-<?php
-
-/*
- * This file is part of the Symfony package.
- *
- * (c) Fabien Potencier <fabien@symfony.com>
- *
- * For the full copyright and license information, please view the LICENSE
- * file that was distributed with this source code.
- */
-
-namespace Symfony\Component\Debug\Tests;
-
-use Symfony\Component\Debug\ExceptionHandler;
-
-class MockExceptionHandler extends ExceptionHandler
-{
-    public $e;
-
-    public function handle(\Exception $e)
-    {
-        $this->e = $e;
-    }
-}
--- a/Tests/phpt/debug_class_loader.phpt
+++ b/Tests/phpt/debug_class_loader.phpt
@@ -23,5 +23,6 @@ class_exists(ExtendedFinalMethod::class);

 ?>
 --EXPECTF--
+%A
 The "Symfony\Component\Debug\Tests\Fixtures\FinalMethod::finalMethod()" method is considered final. It may change without further notice as of its next major version. You should not extend it from "Symfony\Component\Debug\Tests\Fixtures\ExtendedFinalMethod".
 The "Symfony\Component\Debug\Tests\Fixtures\FinalMethod::finalMethod2()" method is considered final. It may change without further notice as of its next major version. You should not extend it from "Symfony\Component\Debug\Tests\Fixtures\ExtendedFinalMethod".
--- a/Tests/phpt/decorate_exception_hander.phpt
+++ b/Tests/phpt/decorate_exception_hander.phpt
@@ -26,6 +26,7 @@ if (true) {

 ?>
 --EXPECTF--
+%A
 object(Symfony\Component\Debug\Exception\ClassNotFoundException)#%d (8) {
  ["message":protected]=>
  string(131) "Attempted to load class "missing" from namespace "Symfony\Component\Debug".
--- a/Tests/phpt/exception_rethrown.phpt
+++ b/Tests/phpt/exception_rethrown.phpt
@@ -14,7 +14,7 @@ require $vendor.'/vendor/autoload.php';
 if (true) {
    class TestLogger extends \Psr\Log\AbstractLogger
    {
-        public function log($level, $message, array $context = [])
+        public function log($level, $message, array $context = []): void
        {
            echo $message, "\n";
        }
--- a/Tests/phpt/fatal_with_nested_handlers.phpt
+++ b/Tests/phpt/fatal_with_nested_handlers.phpt
@@ -35,6 +35,7 @@ array(1) {
  [0]=>
  string(37) "Error and exception handlers do match"
 }
+%A
 object(Symfony\Component\Debug\Exception\FatalErrorException)#%d (%d) {
  ["message":protected]=>
  string(179) "Error: Class Symfony\Component\Debug\Broken contains 1 abstract method and must therefore be declared abstract or implement the remaining methods (JsonSerializable::jsonSerialize)"
--- a/composer.json
+++ b/composer.json
@@ -1,7 +1,7 @@
 {
    "name": "symfony/debug",
    "type": "library",
-    "description": "Symfony Debug Component",
+    "description": "Provides tools to ease debugging PHP code",
    "keywords": [],
    "homepage": "https://symfony.com",
    "license": "MIT",
@@ -16,14 +16,14 @@
        }
    ],
    "require": {
-        "php": "^7.1.3",
-        "psr/log": "~1.0"
+        "php": ">=7.1.3",
+        "psr/log": "^1|^2|^3"
    },
    "conflict": {
        "symfony/http-kernel": "<3.4"
    },
    "require-dev": {
-        "symfony/http-kernel": "~3.4|~4.0"
+        "symfony/http-kernel": "^3.4|^4.0|^5.0"
    },
    "autoload": {
        "psr-4": { "Symfony\\Component\\Debug\\": "" },
@@ -31,10 +31,5 @@
            "/Tests/"
        ]
    },
-    "minimum-stability": "dev",
-    "extra": {
-        "branch-alias": {
-            "dev-master": "4.3-dev"
-        }
-    }
+    "minimum-stability": "dev"
 }
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -14,10 +14,7 @@

    <testsuites>
        <testsuite name="Symfony Debug Component Test Suite">
-            <directory>./Tests/</directory>
-        </testsuite>
-        <testsuite name="Symfony Debug Extension Test Suite">
-            <directory suffix=".phpt">./Resources/ext/tests/</directory>
+            <directory suffix=".phpt">./Tests/</directory>
        </testsuite>
    </testsuites>