current_user_can fatal error

[kkmuffme]

current_user_can uses ​https://developer.wordpress.org/reference/functions/wp_get_current_user/ internally, however this function is only loaded only much after current_user_can is declared. This means using current_user_can on e.g. mu_plugins_loaded or plugin_loaded hook will result in a fatal error.

Changing the wp_get_current_user() call in there to _wp_get_current_user() fixes that issue, but then it fails on wp_set_current_user() which is pluggable too.

[siliconforks]

Note that it has always been documented that the earliest you can access the current user is in the init action.

​https://developer.wordpress.org/apis/hooks/action-reference/#actions-run-during-a-typical-request

So I would not expect it to work before init. (But it might make more sense to display a useful error message instead of crashing due to a missing function.)

[kkmuffme]

I know, but the problem is that this can accidentally make a plugin break another plugin or WP core alltogether with a fatal error.

e.g. plugin A:

<?php
function my_cb_a( $value ) {
    if ( isset( $_GET['foo'] ) && current_user_can( 'administrator' ) ) {
        return 'UTF-8';
    }

    return $value;
}
add_filter( 'pre_option_blog_charset', 'my_cb_a' );

plugin B:

<?php
function my_cb_b() {
    $example = get_option( 'blog_charset' );
}
add_action( 'plugins_loaded', 'my_cb_b' );

[hellofromTonya]

Changing the version that introduced this code. It was introduced WP 2.0.3 via [3566] (18 years ago).

[hellofromTonya]

Hello @kkmuffme,

Welcome back to WordPress Core Trac.

This has been discussed multiple times throughout the years. The first discussion and reasoning for it as well as using init was in #5265. More recently, it was discussed in #59000.

I'm closing this ticket as a duplicate of #5265. Doing so shifts the discussion into 1 ticket. After reviewing #5265, if there are new reasonings or concerns, please share those in that ticket and consider reopening it to restart and renew the discussion and considerations. Thanks.

[SergeyBiryukov]

Also related: #16363, #23861, #55563.