Custom capability conflict with W3TC plugin

[frankiejarrett]

A user reported in the forums that while running W3 Total Cache with the New Relic setting enabled the Stream Records page disappears.

I've isolated the problem to these lines in the W3TC plugin.

It seems that $current_user->roles is just an empty array when Stream is enabled.

If you change the VIEW_CAP constant to manage_options everything works perfectly fine. So something about the way Stream is using a custom capability might be causing a conflict here, but I haven't been able to pinpoint exactly which plugin is to blame.

/cc @kucrut @shadyvb

[kucrut]

It seems that $current_user->roles is just an empty array when Stream is enabled.

This is not Stream's fault. WT3C modified the global $current_user->roles when New Relic is enabled. So, even when Stream's not active, it will be empty.

[kucrut]

@fjarrett The only way I can think of to work-around this, is to also use $user->caps in WP_Stream_Admin::_filter_user_caps(), so something like:

public static function _filter_user_caps( $allcaps, $caps, $args, $user = null ) {
    $user  = is_a( $user, 'WP_User' ) ? $user : wp_get_current_user();
    $roles = array_unique( array_merge( $user->roles, array_keys( $user->caps ) ) );

    foreach ( $caps as $cap ) {
        if ( self::VIEW_CAP === $cap ) {
            foreach ( $roles as $role ) {
                if ( self::_role_can_view_stream( $role ) ) {
                    $allcaps[ $cap ] = true;
                    break 2;
                }
            }
        }
    }

    return $allcaps;
}

[frankiejarrett]

@kucrut Thanks for looking into this.

I feel like we shouldn't have to implement workarounds for other plugins not following best practices, and I assume that modifying this global would fall into that category.

@shadyvb Your thoughts?

[shadyvb]

While that seems like a workaround, that's what core is actually doing:
https://github.com/WordPress/WordPress/blob/c67c9565f1495255807069fdb39dac914046b1a0/wp-includes/capabilities.php#L758

if ( is_array( $this->caps ) )
    $this->roles = array_filter( array_keys( $this->caps ), array( $wp_roles, 'is_role' ) );

Risking situations where those two keys are modified inappropriately, would be the fault of whatever code that changes them ( like W3TC ). But what @kucrut is suggesting seems pretty valid to me ( not sure if it'd work though, haven't tested ).

[shadyvb]

Out of curiosity, has anyone reported this to W3TC yet ?

[frankiejarrett]

@shadyvb Not that we know of, I'll ask the OP.

[frankiejarrett]

The OP has reported this to W3TC to get their feedback on the matter as well.