PHP 8.1 deprecation notice for gmt_offset on wp-admin/options.php

[SergeyBiryukov]

1. In General Settings, select a named timezone (not a UTC+- one).
2. When saving the settings, there is a PHP 8.1 deprecation notice:

   Deprecated: preg_replace(): Passing null to parameter #3 ($subject) of type array|string is deprecated in wp-includes/formatting.php on line 4862
   

The notice comes from sanitize_option():

case 'gmt_offset':
	$value = preg_replace( '/[^0-9:.-]/', '', $value ); // Strips slashes.
	break;

Appears to be caused by this fragment in wp-admin/options.php where the default value for any options not passed in the current $_POST request (which happens to be gmt_offset here) is set to null:

foreach ( $options as $option ) {

	...

	$option = trim( $option );
	$value  = null;
	if ( isset( $_POST[ $option ] ) ) {
		$value = $_POST[ $option ];
		if ( ! is_array( $value ) ) {
			$value = trim( $value );
		}
		$value = wp_unslash( $value );
	}
	update_option( $option, $value );
}

Updated the options table if the value exists in the POST request

Trac ticket: https://core.trac.wordpress.org/ticket/57728

[dhrupo]

Hi @SergeyBiryukov,
Please check the code and let me know :)

[hrdelwar]

hi @dhrupo, just checked the PR and it works perfectly.

[hasanmisbah]

hi @dhrupo Your PR. was fantastic

[SergeyBiryukov]

Thanks for the PR!

Looks like it might have unintended consequences though, as some options, e.g. blog_public, actually rely on null being passed to update_option() if the option was not sent to options.php, see [21849] and [21851] / #16416.

I believe we can specifically check if gmt_offset is a string in sanitize_option(), see 57728.diff​.

[oglekler]

This can be a quick fix as needed with patch Sergey as suggested but I believe that it needs further discussion.

Is it ok to have null as gmt_offset in the first place? I wonder if it needs to be checked from where it's coming from. But somehow with PHP8.1 (by online testing tool) I am getting a fatal error, and it needs to be addressed anyway. If this is the case, others placed when preg_replace() is used, need to be checked to avoid receiving null as subject.

Adding a check to verify data type
if $value is_string returns $value, or else returns empty string.
This prevents deprecation notice and also saves data as empty string as saved in prior php versions

Trac ticket: https://core.trac.wordpress.org/ticket/57728

[adi3890]

@oglekler @SergeyBiryukov Just modified the logic of is_string check with a default value as empty string. This way data will be saved as empty string as it is saved now, and this validation prevents php deprecation notice.

[mukesh27]

@SergeyBiryukov do you have capacity to review the latest PR?

[SergeyBiryukov]

In 56132:

Options, Meta APIs: Check if the gmt_offset value is numeric in sanitize_option().

When saving the settings via the admin UI, the default value for any options not passed in the current $_POST request is set to null in wp-admin/options.php. Some options, e.g. blog_public, then rely on null being passed to update_option() to determine whether the value was changed or not.

This commit resolves a PHP 8.1 deprecation notice when saving the gmt_offset option without any changes:

Deprecated: preg_replace(): Passing null to parameter #3 ($subject) of type array|string is deprecated

Includes a similar fix for the blog_charset option.

Follow-up to [4112], [4329], [5541], [21849].

Props adi3890, dhrupo, hrdelwar, hasanmisbah, oglekler, mukesh27, SergeyBiryukov.
Fixes #57728.

Thanks for the PR! Merged in r56132.

Thanks for the PR! Merged in r56132.