Title: #334: Print a warning when enumeration is requested but disabled
Here's how I would go about the warning:
- add a boolean into struct rctx, something like 'enumeration_warn_logged"
- when the code reaches `cache_req_validate_domain_enumeration` and we reach the block
where the domain doesn't support enumeration and this boolean is unset, call either
sss_log with some lower level (NOTICE?) or just DEBUG with IMPORTANT_INFO warning that
enumeration was requested, but is not enabled.
See the full comment at https://github.com/SSSD/sssd/pull/334#issuecomment-325985028