Determines whether the current post is open for comments.

For more information on this and similar theme functions, check out
the {@link Conditional Tags} article in the Theme Developer Handbook.

function comments_open( $post = null ) {
	$_post = get_post( $post );

	$post_id = $_post ? $_post->ID : 0;
	$open    = ( $_post && ( 'open' === $_post->comment_status ) );

	/**
	 * Filters whether the current post is open for comments.
	 *
	 * @since 2.5.0
	 *
	 * @param bool $open    Whether the current post is open for comments.
	 * @param int  $post_id The post ID.
	 */
	return apply_filters( 'comments_open', $open, $post_id );
}