Ticket #16843: test-16843.php

<?php

add_action('init', function() {
        register_post_type( 'foo', array(
                'has_archive' => true,
                'public' => true,
                'label' => 'Foo',
        ) );

        global $wp_rewrite;

        var_dump( wp_unique_post_slug( $wp_rewrite->pagination_base, 1, 'publish', 'foo', 0 ) );
});