Infinite callback loop when 'priority' is not numeric in php 8.x

[mzou23]

The behavior of min(array) has changed in php 8.x. Prior to php 8,
min(array('a', 1,2,3)) returns 'a'. In php 8.x, it returns 1.

This has some unexpected effects on wordpress filters. The following code

function test_action() { add_action( 'admin_enqueue_scripts', function(){}, 'a');}
add_action( 'admin_enqueue_scripts', 'test_action' , 10);

which works on php 7, will result in an infinite loop on php 8.x. Strictly speaking, this is not a bug, as using 'a' instead of a numeric value for priority is incorrect. However, wordpress does not complain its use.

Here is a simple fix. Add a check in wp-includes/class-wp-hook.php, on line 83. Either change the priority to a numeric value or barf and bail out. I think something like

 if( ! is_numeric($priority) )  $priority = 10;

will be safe.

See: https://core.trac.wordpress.org/ticket/62314

Trac ticket:

[johnbillion]

Related/dupe: #30875 (see recent comments).