Source

File: wp-includes/comment.php

function wp_spam_comment( $comment_id ) {
	$comment = get_comment( $comment_id );
	if ( ! $comment ) {
		return false;
	}

	/**
	 * Fires immediately before a comment is marked as Spam.
	 *
	 * @since 2.9.0
	 * @since 4.9.0 Added the `$comment` parameter.
	 *
	 * @param int        $comment_id The comment ID.
	 * @param WP_Comment $comment    The comment to be marked as spam.
	 */
	do_action( 'spam_comment', $comment->comment_ID, $comment );

	if ( wp_set_comment_status( $comment, 'spam' ) ) {
		delete_comment_meta( $comment->comment_ID, '_wp_trash_meta_status' );
		delete_comment_meta( $comment->comment_ID, '_wp_trash_meta_time' );
		add_comment_meta( $comment->comment_ID, '_wp_trash_meta_status', $comment->comment_approved );
		add_comment_meta( $comment->comment_ID, '_wp_trash_meta_time', time() );

		/**
		 * Fires immediately after a comment is marked as Spam.
		 *
		 * @since 2.9.0
		 * @since 4.9.0 Added the `$comment` parameter.
		 *
		 * @param int        $comment_id The comment ID.
		 * @param WP_Comment $comment    The comment marked as spam.
		 */
		do_action( 'spammed_comment', $comment->comment_ID, $comment );

		return true;
	}

	return false;
}