It looks like a registered shutdown function is performing infinite recursion.

The MWE produces a segfault with PHP 7.3 too


php -v               
PHP 7.3.0-2+ubuntu18.04.1+deb.sury.org+1 (cli) (built: Dec 17 2018 09:22:47) ( NTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.3.0-dev, Copyright (c) 1998-2018 Zend Technologies
    with Zend OPcache v7.3.0-2+ubuntu18.04.1+deb.sury.org+1, Copyright (c) 1999-2018, by Zend Technologies


php segfault.php     
PHP Fatal error:  Allowed memory size of 268435456 bytes exhausted (tried to allocate 268435488 bytes) in /tmp/php-segfault-mwe/segfault.php on line 13
[1]    649 segmentation fault (core dumped)  php segfault.php

> It looks like a registered shutdown function is performing
> infinite recursion.

Right.  Relevant excerpt from a trace:

-> Symfony\Component\Debug\ErrorHandler->handleException($exception = class Symfony\Component\Debug\Exception\OutOfMemoryException { protected $message = 'Error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 268435488 bytes)'; private ${Exception}string = ''; protected $code = 0; protected $file = 'C:\\php-sdk\\phpdev\\vc15\\x64\\75899\\php-segfault-mwe\\segfault.php'; protected $line = 13; private ${Exception}trace = []; private ${Exception}previous = NULL; protected $severity = 1 }, $error = ['type' => 1, 'message' => 'Allowed memory size of 268435456 bytes exhausted (tried to allocate 268435488 bytes)', 'file' => 'C:\\php-sdk\\phpdev\\vc15\\x64\\75899\\php-segfault-mwe\\segfault.php', 'line' => 13]) C:\php-sdk\phpdev\vc15\x64\75899\php-segfault-mwe\vendor\symfony\symfony\src\Symfony\Component\Debug\ErrorHandler.php:622
  -> ErrorException->getSeverity() C:\php-sdk\phpdev\vc15\x64\75899\php-segfault-mwe\vendor\symfony\symfony\src\Symfony\Component\Debug\ErrorHandler.php:504
  -> Monolog\ErrorHandler->handleException($e = class Symfony\Component\Debug\Exception\OutOfMemoryException { protected $message = 'Error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 268435488 bytes)'; private ${Exception}string = ''; protected $code = 0; protected $file = 'C:\\php-sdk\\phpdev\\vc15\\x64\\75899\\php-segfault-mwe\\segfault.php'; protected $line = 13; private ${Exception}trace = []; private ${Exception}previous = NULL; protected $severity = 1 }) C:\php-sdk\phpdev\vc15\x64\75899\php-segfault-mwe\vendor\symfony\symfony\src\Symfony\Component\Debug\ErrorHandler.php:541
    -> get_class($object = class Symfony\Component\Debug\Exception\OutOfMemoryException { protected $message = 'Error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 268435488 bytes)'; private ${Exception}string = ''; protected $code = 0; protected $file = 'C:\\php-sdk\\phpdev\\vc15\\x64\\75899\\php-segfault-mwe\\segfault.php'; protected $line = 13; private ${Exception}trace = []; private ${Exception}previous = NULL; protected $severity = 1 }) C:\php-sdk\phpdev\vc15\x64\75899\php-segfault-mwe\vendor\monolog\monolog\src\Monolog\ErrorHandler.php:135
    -> Exception->getMessage() C:\php-sdk\phpdev\vc15\x64\75899\php-segfault-mwe\vendor\monolog\monolog\src\Monolog\ErrorHandler.php:135
    -> Exception->getFile() C:\php-sdk\phpdev\vc15\x64\75899\php-segfault-mwe\vendor\monolog\monolog\src\Monolog\ErrorHandler.php:135
    -> Exception->getLine() C:\php-sdk\phpdev\vc15\x64\75899\php-segfault-mwe\vendor\monolog\monolog\src\Monolog\ErrorHandler.php:135
    -> sprintf($format = 'Uncaught Exception %s: "%s" at %s line %s', ...$args = variadic(0 => 'Symfony\\Component\\Debug\\Exception\\OutOfMemoryException', 1 => 'Error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 268435488 bytes)', 2 => 'C:\\php-sdk\\phpdev\\vc15\\x64\\75899\\php-segfault-mwe\\segfault.php', 3 => 13)) C:\php-sdk\phpdev\vc15\x64\75899\php-segfault-mwe\vendor\monolog\monolog\src\Monolog\ErrorHandler.php:135
    -> Psr\Log\NullLogger->log($level = 'error', $message = 'Uncaught Exception Symfony\\Component\\Debug\\Exception\\OutOfMemoryException: "Error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 268435488 bytes)" at C:\\php-sdk\\phpdev\\vc15\\x64\\75899\\php-segfault-mwe\\segfault.php line 13', $context = ['exception' => class Symfony\Component\Debug\Exception\OutOfMemoryException { protected $message = 'Error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 268435488 bytes)'; private ${Exception}string = ''; protected $code = 0; protected $file = 'C:\\php-sdk\\phpdev\\vc15\\x64\\75899\\php-segfault-mwe\\segfault.php'; protected $line = 13; private ${Exception}trace = [...]; private ${Exception}previous = NULL; protected $severity = 1 }]) C:\php-sdk\phpdev\vc15\x64\75899\php-segfault-mwe\vendor\monolog\monolog\src\Monolog\ErrorHandler.php:136
    -> call_user_func:{C:\php-sdk\phpdev\vc15\x64\75899\php-segfault-mwe\vendor\monolog\monolog\src\Monolog\ErrorHandler.php:140}($function_name = [0 => class Symfony\Component\Debug\ErrorHandler { private $levels = [...]; private $loggers = [...]; private $thrownErrors = 4352; private $scopedErrors = 8191; private $tracedErrors = 30715; private $screamedErrors = 85; private $loggedErrors = 0; private $traceReflector = class ReflectionProperty { ... }; private $isRecursive = 0; private $isRoot = TRUE; private $exceptionHandler = [...]; private $bootstrappingLogger = NULL }, 1 => 'handleException'], ...$parameters = variadic(0 => class Symfony\Component\Debug\Exception\OutOfMemoryException { protected $message = 'Error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 268435488 bytes)'; private ${Exception}string = ''; protected $code = 0; protected $file = 'C:\\php-sdk\\phpdev\\vc15\\x64\\75899\\php-segfault-mwe\\segfault.php'; protected $line = 13; private ${Exception}trace = []; private ${Exception}previous = NULL; protected $severity = 1 })) C:\php-sdk\phpdev\vc15\x64\75899\php-segfault-mwe\vendor\monolog\monolog\src\Monolog\ErrorHandler.php:140
      -> Symfony\Component\Debug\ErrorHandler->handleException($exception = class Symfony\Component\Debug\Exception\OutOfMemoryException { protected $message = 'Error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 268435488 bytes)'; private ${Exception}string = ''; protected $code = 0; protected $file = 'C:\\php-sdk\\phpdev\\vc15\\x64\\75899\\php-segfault-mwe\\segfault.php'; protected $line = 13; private ${Exception}trace = []; private ${Exception}previous = NULL; protected $severity = 1 }, $error = ???) C:\php-sdk\phpdev\vc15\x64\75899\php-segfault-mwe\vendor\monolog\monolog\src\Monolog\ErrorHandler.php:140
        -> ErrorException->getSeverity() C:\php-sdk\phpdev\vc15\x64\75899\php-segfault-mwe\vendor\symfony\symfony\src\Symfony\Component\Debug\ErrorHandler.php:504
        -> Monolog\ErrorHandler->handleException($e = class Symfony\Component\Debug\Exception\OutOfMemoryException { protected $message = 'Error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 268435488 bytes)'; private ${Exception}string = ''; protected $code = 0; protected $file = 'C:\\php-sdk\\phpdev\\vc15\\x64\\75899\\php-segfault-mwe\\segfault.php'; protected $line = 13; private ${Exception}trace = []; private ${Exception}previous = NULL; protected $severity = 1 }) C:\php-sdk\phpdev\vc15\x64\75899\php-segfault-mwe\vendor\symfony\symfony\src\Symfony\Component\Debug\ErrorHandler.php:541
          -> get_class($object = class Symfony\Component\Debug\Exception\OutOfMemoryException { protected $message = 'Error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 268435488 bytes)'; private ${Exception}string = ''; protected $code = 0; protected $file = 'C:\\php-sdk\\phpdev\\vc15\\x64\\75899\\php-segfault-mwe\\segfault.php'; protected $line = 13; private ${Exception}trace = []; private ${Exception}previous = NULL; protected $severity = 1 }) C:\php-sdk\phpdev\vc15\x64\75899\php-segfault-mwe\vendor\monolog\monolog\src\Monolog\ErrorHandler.php:135
          -> Exception->getMessage() C:\php-sdk\phpdev\vc15\x64\75899\php-segfault-mwe\vendor\monolog\monolog\src\Monolog\ErrorHandler.php:135
          -> Exception->getFile() C:\php-sdk\phpdev\vc15\x64\75899\php-segfault-mwe\vendor\monolog\monolog\src\Monolog\ErrorHandler.php:135
          -> Exception->getLine() C:\php-sdk\phpdev\vc15\x64\75899\php-segfault-mwe\vendor\monolog\monolog\src\Monolog\ErrorHandler.php:135
          -> sprintf($format = 'Uncaught Exception %s: "%s" at %s line %s', ...$args = variadic(0 => 'Symfony\\Component\\Debug\\Exception\\OutOfMemoryException', 1 => 'Error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 268435488 bytes)', 2 => 'C:\\php-sdk\\phpdev\\vc15\\x64\\75899\\php-segfault-mwe\\segfault.php', 3 => 13)) C:\php-sdk\phpdev\vc15\x64\75899\php-segfault-mwe\vendor\monolog\monolog\src\Monolog\ErrorHandler.php:135
          -> Psr\Log\NullLogger->log($level = 'error', $message = 'Uncaught Exception Symfony\\Component\\Debug\\Exception\\OutOfMemoryException: "Error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 268435488 bytes)" at C:\\php-sdk\\phpdev\\vc15\\x64\\75899\\php-segfault-mwe\\segfault.php line 13', $context = ['exception' => class Symfony\Component\Debug\Exception\OutOfMemoryException { protected $message = 'Error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 268435488 bytes)'; private ${Exception}string = ''; protected $code = 0; protected $file = 'C:\\php-sdk\\phpdev\\vc15\\x64\\75899\\php-segfault-mwe\\segfault.php'; protected $line = 13; private ${Exception}trace = [...]; private ${Exception}previous = NULL; protected $severity = 1 }]) C:\php-sdk\phpdev\vc15\x64\75899\php-segfault-mwe\vendor\monolog\monolog\src\Monolog\ErrorHandler.php:136
          -> call_user_func:{C:\php-sdk\phpdev\vc15\x64\75899\php-segfault-mwe\vendor\monolog\monolog\src\Monolog\ErrorHandler.php:140}($function_name = [0 => class Symfony\Component\Debug\ErrorHandler { private $levels = [...]; private $loggers = [...]; private $thrownErrors = 4352; private $scopedErrors = 8191; private $tracedErrors = 30715; private $screamedErrors = 85; private $loggedErrors = 0; private $traceReflector = class ReflectionProperty { ... }; private $isRecursive = 0; private $isRoot = TRUE; private $exceptionHandler = [...]; private $bootstrappingLogger = NULL }, 1 => 'handleException'], ...$parameters = variadic(0 => class Symfony\Component\Debug\Exception\OutOfMemoryException { protected $message = 'Error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 268435488 bytes)'; private ${Exception}string = ''; protected $code = 0; protected $file = 'C:\\php-sdk\\phpdev\\vc15\\x64\\75899\\php-segfault-mwe\\segfault.php'; protected $line = 13; private ${Exception}trace = []; private ${Exception}previous = NULL; protected $severity = 1 })) C:\php-sdk\phpdev\vc15\x64\75899\php-segfault-mwe\vendor\monolog\monolog\src\Monolog\ErrorHandler.php:140
            -> Symfony\Component\Debug\ErrorHandler->handleException($exception = class Symfony\Component\Debug\Exception\OutOfMemoryException { protected $message = 'Error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 268435488 bytes)'; private ${Exception}string = ''; protected $code = 0; protected $file = 'C:\\php-sdk\\phpdev\\vc15\\x64\\75899\\php-segfault-mwe\\segfault.php'; protected $line = 13; private ${Exception}trace = []; private ${Exception}previous = NULL; protected $severity = 1 }, $error = ???) C:\php-sdk\phpdev\vc15\x64\75899\php-segfault-mwe\vendor\monolog\monolog\src\Monolog\ErrorHandler.php:140

This causes a stack overflow, and this ticket is basically a
duplicate of bug #64196.

Tip: avoid infinite recursion!