TypeError in wp_check_filetype_and_ext hook: bool values into $mimes argument can be passed

[platonkristinin]

​https://developer.wordpress.org/reference/hooks/wp_check_filetype_and_ext/ API doc states that $mimes argument is keyed array:

 $mimes string[]
    Array of mime types keyed by their file extension regex.

But by fact into this argument can be passed a bool data type. When I add my custom hook

<?php
function my_check_filetype_and_ext(array $wp_check_filetype_and_ext, string $file, string $filename, array $mimes, string|false $real_mime): array {
}

add_filter('wp_check_filetype_and_ext', [$this, 'my_check_svg_filetype_and_ext'], accepted_args: 5);

then I get following error:

PHP Fatal error: Uncaught TypeError: Argument #4 ($mimes) must be of type array, bool given

So there is a bug in documentation or in hook implementation. I'm leaning towards the second, because mimes always should be array and there are no reasons to pass boolean values.

Workaround is allow false values for $mimes:

array|false $mimes

[johnbillion]

Thanks for the report. It does indeed seem that false can get passed to the $mimes parameter, which is incorrect. This parameter should be an array of strings or null.

Ref: ​https://github.com/WordPress/wordpress-develop/blob/261ab3fa5de7b1972dd52e938cdb4abd8d9014df/src/wp-admin/includes/file.php#L931 . $mimes has a fallback of false here when it should be null: ​https://github.com/WordPress/wordpress-develop/blob/261ab3fa5de7b1972dd52e938cdb4abd8d9014df/src/wp-admin/includes/file.php#L893.

[pkbhatt]

Added patch for the bug

[pkbhatt]

Fixed the issue and added patch

[johnbillion]

In 55872:

Media: Correct the fallback value passed to the $mimes parameter of wp_check_filetype_and_ext() from _wp_handle_upload(), and update corresponding documentation.

Previously when the mimes element was not specified in the overrides array passed to _wp_handle_upload() it resulted in boolean false being passed to this parameter, which is incorrect. The fallback value should be null.

Props platonkristinin, pkbhatt

Fixes #58349