wp-includes/class-wp-customize-manager.php:5796Returns whether there are published pages.
bool public function has_published_pages() { $setting = $this->get_setting( 'nav_menus_created_posts' ); if ( $setting ) { foreach ( $setting->value() as $post_id ) { if ( 'page' === get_post_type( $post_id ) ) { return true; } } } return 0 !== count( get_pages( array( 'number' => 1, 'hierarchical' => 0, ) ) ); }Introduced in 4.7.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/class-wp-customize-manager.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.