Description:
------------
E_NOTICE maybe result in symbol table resize, which will result in segfault

Test script:
---------------
function test() {
    for ($n = 'a'; $n < 'g'; $n++) {
        $$n = array();
    }
    $$n = array();
    $$n .= "test";
    return $$n;
}   


var_dump(test2());

Expected result:
----------------
no segfault

Actual result:
--------------
segfault 

valgrind:
PHP Notice:  Array to string conversion in /tmp/1.php on line 15

Notice: Array to string conversion in /tmp/1.php on line 15
==12029== Invalid read of size 1
==12029==    at 0x984238: _zval_dtor (zend_variables.h:41)
==12029==    by 0x98CF70: concat_function (zend_operators.c:1611)
==12029==    by 0xA137FD: zend_binary_assign_op_helper_SPEC_VAR_CONST (zend_vm_execute.h:16581)
==12029==    by 0xA13B7D: ZEND_ASSIGN_CONCAT_SPEC_VAR_CONST_HANDLER (zend_vm_execute.h:16739)
==12029==    by 0x9F0BB4: execute_ex (zend_vm_execute.h:414)
==12029==    by 0x9F0CC6: zend_execute (zend_vm_execute.h:458)
==12029==    by 0x995C1E: zend_execute_scripts (zend.c:1427)
==12029==    by 0x902F01: php_execute_script (main.c:2484)
==12029==    by 0xA55028: do_cli (php_cli.c:974)
==12029==    by 0xA561EC: main (php_cli.c:1345)
==12029==  Address 0xb722de9 is 265 bytes inside a block of size 288 free'd
==12029==    at 0x4C2BDEC: free (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==12029==    by 0x9624DE: _efree (zend_alloc.c:2453)
==12029==    by 0x9A9251: zend_hash_do_resize (zend_hash.c:880)
==12029==    by 0x9A81E9: _zend_hash_add_or_update_i (zend_hash.c:591)
==12029==    by 0x9A85F0: _zend_hash_str_update_ind (zend_hash.c:662)
==12029==    by 0x9807BF: zend_set_local_var_str (zend_execute_API.c:1653)
==12029==    by 0x9004C7: php_error_cb (main.c:1203)
==12029==    by 0x7547C5: soap_error_handler (soap.c:2139)
==12029==    by 0x994CEB: zend_error (zend.c:1154)
==12029==    by 0x986E11: _zval_get_string_func (zend_operators.c:834)
==12029==    by 0x9934F2: zend_make_printable_zval (zend.c:249)
==12029==    by 0x98CF45: concat_function (zend_operators.c:1605)