Restore the ability to short-circuit core redirects

[DrewAPicture]

When the wp_redirect filter was added in [4407], the point was to make it possible to "cancel" a redirect by filtering the location. However, following [16847], exit; calls for wp_redirect() were added all over core.

The problem with adding exit in the way we did in [16847], was that it thereafter prevented short-circuiting a redirect because exit is called whether the redirect is canceled or not.

So in that vein, rather than doing:

<?php
wp_redirect( admin_url( 'something' ) );
exit;

We should take a cue from [24996] and check for a successful redirect before exiting.

<?php
if ( wp_redirect( admin_url( 'something' ) ) )
        exit;

Patch attached.

[johnbillion]

Surely this introduces unexpected behaviour all over the place if you start cancelling redirects? The scripts will continue processing after the cancelled redirect, when they'd normally be stopped with exit().

[SergeyBiryukov]

Yes, there are probably a lot of instances where the redirect should never be canceled.

If there are redirects that can be canceled for a valid use case, I'd suggest to deal with on a case by case basis.

[DrewAPicture]

Replying to SergeyBiryukov:

Yes, there are probably a lot of instances where the redirect should never be canceled.

If there are redirects that can be canceled for a valid use case, I'd suggest to deal with them on a case by case basis.

Fair enough.

My original use-case was to cancel the redirect to media-new.php from post-new.php?post_type=attachment (which I quickly found was impossible).

I guess we should remove the "allows the wp_redirect filter to cancel a redirect" bit in wp_redirect() then. No longer possible post-3.1. I'll create a separate ticket.

[DrewAPicture]

Filter docs for wp_redirect(): #25215