Description:
------------
Pretty simple to reproduce. Happens only when the variable is not initialized first. Also sometimes requires two or three invocations until it first crashes, no idea why. Needs opcache.enable_cli=1 of course to reproduce.

Does not happen on 7.1.13. Also happens on other OSes (e.g. Ubuntu 14/16, with self-built PHP).

Test script:
---------------
<?php

function foo() {
	@$bar++;
}

foo();


Actual result:
--------------
$ gdb php-7.2.1/bin/php
(gdb) run -dzend_extension=opcache.so -dopcache.enable_cli=1 sigsegv72.php
Starting program: php-7.2.1/bin/php -dzend_extension=opcache.so -dopcache.enable_cli=1 sigsegv72.php
[New Thread 0x1703 of process 46816]
warning: unhandled dyld version (15)

Thread 2 received signal SIGSEGV, Segmentation fault.
0x0000000100636c5b in execute_ex (ex=0x101222030)
    at Zend/zend_vm_execute.h:59726
59726			if (UNEXPECTED((ret = ((opcode_handler_t)OPLINE->handler)(ZEND_OPCODE_HANDLER_ARGS_PASSTHRU)) != 0)) {
(gdb) bt
#0  0x0000000100636c5b in execute_ex (ex=0x101222030)
    at Zend/zend_vm_execute.h:59726
#1  0x0000000100636e6a in zend_execute (op_array=0x10127b600, return_value=0x0)
    at Zend/zend_vm_execute.h:63763
#2  0x00000001005cdc92 in zend_execute_scripts (type=8, retval=0x0, 
    file_count=3) at Zend/zend.c:1496
#3  0x0000000100520932 in php_execute_script (primary_file=0x7ffeefbff318)
    at main/main.c:2590
#4  0x00000001006f3d9d in do_cli (argc=4, argv=0x7ffeefbffa40)
    at sapi/cli/php_cli.c:1011
#5  0x00000001006f2d2c in main (argc=4, argv=0x7ffeefbffa40)
    at sapi/cli/php_cli.c:1404