Coding Standards: Pass $count to the second _list_meta_row() call

[csemazharul]

Trac ticket: https://core.trac.wordpress.org/ticket/65934

While reading wp_ajax_add_meta() I noticed it passes a variable that doesn't exist.

In [61224] the variable $c was renamed to $count. It's used in three places, but only two of them were changed:

// src/wp-admin/includes/ajax-actions.php

$count = 0;                           // line 1637 - changed
_list_meta_row( $meta, $count )       // line 1703 - changed
_list_meta_row( array( ... ), $c )    // line 1750 - still says $c

So the last call passes $c, and $c isn't defined anywhere in the function.

Normally PHP would warn about that. It doesn't here, because the second argument is taken by reference:

function _list_meta_row( $entry, &$count ) {

When you pass an undefined variable by reference, PHP just creates it and sets it to null. No notice, no error. That's also why PHPStan doesn't flag it - $c is missing from tests/phpstan/baselines/variable.undefined.neon, even though five other variables from this same file are listed there.

This changes that one line to $count.

What breaks

Nothing right now. $count is never read after either call, since $response->send() runs immediately, so the output is identical before and after.

I'm raising it because the two calls no longer match each other, and if someone uses $count after that call later on, it will quietly hold the wrong value.

Testing

tests/phpunit/tests/ajax/wpAjaxAddMeta.php already covers this code path in test_wp_ajax_add_meta_allows_empty_values_on_updating():

phpunit --filter test_wp_ajax_add_meta

It passes before and after, which is what you'd expect since the behavior doesn't change.

Affects 7.0, 7.1 and trunk. 6.9 and earlier are fine - they still use $c in all three places.

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