I came across a subtle bug a developer introduced into our
application. It took us a month to realize the bug was
there because PHP didn't throw a notice.
http://cvs.php.net/viewvc.cgi/ZendEngine2/zend_execute.c?revision=1.755&view=markup
Down inside zend_fetch_dimension_address(), you'll find this block:
switch(Z_TYPE_P(container)) {
/* ... */
case IS_NULL: {
/* for read-mode only */
if (result) {
result->var.ptr_ptr = &EG(uninitialized_zval_ptr);
PZVAL_LOCK(*result->var.ptr_ptr);
}
if (type==BP_VAR_W || type==BP_VAR_RW) {
zend_error(E_WARNING, "Cannot use a NULL value as an array");
}
break;
}
/* ... */
}
To me, that screams intentional, and since BC trumps reason, this isn't going to change.
-Sara