wp_clear_scheduled_hook does not work when including an $args parameter

[johnbillion]

The value for $args that gets passed from wp_clear_scheduled_hook to wp_unschedule_event gets changed and therefore nothing will get unscheduled as no jobs will have that argument.

The problem is that the value of the $args parameter is detected using array_slice( func_get_args(), 1 ) and this actually places the value of $args inside an array with one element with the value of $args.

The value of $args passed by wp_clear_scheduled_hook('my_hook','hello') to wp_unschedule_event will then look like this:

array
(
    [0] => hello
)

instead of this:

hello

---

The function wp_clear_scheduled_hook is used with the $args parameter in core in three places:

1. Inside wp_delete_post to clear any job which might try to publish a future post which has been deleted.
2. Inside check_and_publish_future_post to clear any job which might try to republish a future post which has been published.
3. Inside _transition_post_status to clear any job which might try to publish a future post which has gone back to draft status.

So according to this bug, these three areas cannot be functioning as expected, as they pass a value in the $args parameter to wp_clear_scheduled_hook.

Patch.

wp_clear_scheduled_hook can currently take multiple values for $args. My patch removes this functionality, but breaking backwards compatibility won't be an issue as this never worked anyway.

Makes perfect sense for this to take an $args array like the rest of them.

We may break some plugins though that have made it work for single arguments.

I wonder if we should put in some backwards compatibility code for them.

Indeed, if a plugin did something like

wp_clear_scheduled_hook('my_hook', 'first_arg', 'second_arg');

it would have worked correctly.

(In [12462]) Fix wp_clear_scheduled_hook() so that it function prototype matches the other cron functions.
Include backwards compatibility code so that plugins that used the old way still work.
Fixes #10468.