prevent users from saving pages with reserved rewrite rules as slugs

bad-slugs.php

<?php

// prevent users from saving pages with reserved rewrite rules as slugs
// includes post types, feeds, and search

function my_reserved_slugs() {
	return array(
		'post',
	    'attachment',
	    'category',
	    'tag',
	    'format',
	    'feed',
	    'atom',
	    'rss',
	    'json',
	    'search',
		'people',
		'course',
		'publication',
		'facility',
		'research'
	);
}

add_filter( 'wp_unique_post_slug_is_bad_hierarchical_slug', 'my_reserved_hierarchical_slugs', 10, 4 );
function my_reserved_hierarchical_slugs( $is_bad_hierarchical_slug, $slug, $post_type, $post_parent ) {
	$reserved = my_reserved_slugs();
    if ( !$post_parent && in_array( $slug, $reserved ) )
        return true;
    return $is_bad_hierarchical_slug;
}

add_filter( 'wp_unique_post_slug_is_bad_flat_slug', 'my_reserved_flat_slugs', 10, 3 );
function my_reserved_flat_slugs( $is_bad_flat_slug, $slug, $post_type ) {
	$reserved = my_reserved_slugs();
    if ( in_array( $slug, $reserved ) )
        return true;
    return $is_bad_flat_slug;
}