[PHP 8] Named parameters in hook `call_user_func_array()` calls

[ayeshrajans]

PHP 8.0 is here, and it comes with named parameters.

While named parameter is a new feature that syntax would simply not work in older PHP versions, ​`call_user_func_array function behaves differently.

WordPress uses call_user_func_array extensively throughout the code, including filters and actions. With PHP 8.0, if the second parameter ($param_arr) is an associative array, PHP tries to call the callable as a named parameter.

See example: ​https://3v4l.org/RhjrU

What this means for WordPress, is that all parameters that a registered action, filter, or a standard "params" value must not be an associative array. This behavior is not warned. If the parameter array keys match function parameters, that is mostly a safe call, but if there is at least one parameter name that does not match, PHP will then raise a fatal error.

One easy way to "normalize" the parameters is to call array_values before calling the function.

Before submitting any patches, I would like to request opinions if this is desirable for WordPress. I guess reports will come in once users start to use PHP 8.0, and it's probably an easier fix at call_user_func_array() call-site rather than the action/filter/params declaration.

Disclosure: I am the author of the page linked at the top of this ticket; I believe it provides more context without typing the whole story.

[jrf]

Duplicate of task 3 of ticket #51553

[ayeshrajans]

You are right, it's better to track at #51553, my apologies about the noise.

[jrf]

Duplicate of #51553.