ldap_sasl_interactive_bind_s prints SASL-related messages on stderr by default, unless you specify LDAP_SASL_QUIET.

This seems wrong.  The whole point of the "interact" function is to handle any required conversation with the user.  In particular, in a GUI application these messages won't go to the user; more likely they will just clutter up some log.

Would the OpenLDAP community be receptive to a patch that directs these messages through the "interact" function?

(I think they have very little value and should just be dropped; that would be OK too.)
SASL username: somename@EXAMPLE.COM
SASL data security layer installed.
Jordan Brown, Oracle ZFS Storage Appliance, Oracle Solaris