Marked functions parameters that are allowed to be NULL. Some APIs were also changed. The non-obvious APIs where NULL parameter was changed to "" are master_service_init() and auth_master_user_list_init(). These checks can currently be enabled only on a patched clang: http://llvm.org/bugs/show_bug.cgi?id=6786

#ifndef IMAP_EXPUNGE_H
#define IMAP_EXPUNGE_H

struct mail_search_arg;

int imap_expunge(struct mailbox *box, struct mail_search_arg *next_search_arg)
	ATTR_NULL(2);

#endif