PHP Deprecated: ltrim(): Passing null to parameter #59154

[NiharRan]

I added a check before filtering the link using the esc_url function.

function next_posts( $max_page = 0, $display = true ) {
$link = get_next_posts_page_link( $max_page );

$output = '';
if ( $link ) {
	$output = esc_url( $link );
}

if ( $display ) {
	echo $output;
} else {
	return $output;
}

}

Trac ticket: 59154

[Rajinsharwar]

LGTM!

[codersantosh]

@NiharRan Ultra-rapid fix 😃

[hellofromtonya]

The change LGTM 👍 But it needs a test. I'll push a test to this PR shortly.

[hellofromtonya]

Seems the service is hiccuping

Pulling wordpress-develop (nginx:alpine)...
received unexpected HTTP status: 503 Service Unavailable

[hellofromtonya]

Running the new test locally on PHP 8.1 using the following command:

npm run test:php -- --filter Tests_Link_NextPosts

Before the fix, the test result:

1) Tests_Link_NextPosts::test_should_return_empty_string_when_no_next_posts_page_link
ltrim(): Passing null to parameter #1 ($string) of type string is deprecated

/var/www/src/wp-includes/formatting.php:4494
/var/www/src/wp-includes/link-template.php:2516
/var/www/tests/phpunit/tests/link/nextPost.php:37

After the fix, the test result:

PHPUnit 9.6.13 by Sebastian Bergmann and contributors.

Warning:       Your XML configuration validates against a deprecated schema.
Suggestion:    Migrate your XML configuration using "--migrate-configuration"!

.                                                                   1 / 1 (100%)

Time: 00:00.328, Memory: 166.50 MB

One of the first things I consider is if the fix breaks BC (backward compatibility). In other words, is the result (except for the deprecation) the same? This is why I forced pushed the test to come before the fix, i.e. to test what the result is.

Before the fix, the result is:

• an empty string is returned.
• On PHP 8.1 and newer, a deprecation is triggered.

After the fix, an empty string is still returned.

This can also be seen in action here across different PHP versions https://3v4l.org/7cIvT. Notice, all versions return an empty string, even on PHP 8.1+.

This means: no BC break 🎉

[hellofromtonya]

As noted here, the fix does indeed resolve the issue while maintaining BC of still returning an empty string.

LGTM 👍 Ready for commit.

[hellofromtonya]

Committed via https://core.trac.wordpress.org/changeset/56740. Thank you everyone for your contributions :)