Source

File: wp-admin/includes/class-wp-comments-list-table.php

protected function get_bulk_actions() {
		global $comment_status;

		$actions = array();
		if ( in_array( $comment_status, array( 'all', 'approved' ), true ) ) {
			$actions['unapprove'] = __( 'Unapprove' );
		}
		if ( in_array( $comment_status, array( 'all', 'moderated' ), true ) ) {
			$actions['approve'] = __( 'Approve' );
		}
		if ( in_array( $comment_status, array( 'all', 'moderated', 'approved', 'trash' ), true ) ) {
			$actions['spam'] = _x( 'Mark as spam', 'comment' );
		}

		if ( 'trash' === $comment_status ) {
			$actions['untrash'] = __( 'Restore' );
		} elseif ( 'spam' === $comment_status ) {
			$actions['unspam'] = _x( 'Not spam', 'comment' );
		}

		if ( in_array( $comment_status, array( 'trash', 'spam' ), true ) || ! EMPTY_TRASH_DAYS ) {
			$actions['delete'] = __( 'Delete permanently' );
		} else {
			$actions['trash'] = __( 'Move to Trash' );
		}

		return $actions;
	}