Currently salt[ldap] only depends on python-ldap. On some systems you need the drop-in replacement for it which additionally supports python3: dev-python/pyldap
So please make salt depend on ldap? ( dev-python/python-ldap || dev-python/pyldap ) instead.
dev-python/pyldap is deprecated and if you need python 3 support, then use >=dev-python/python-ldap-3.0 which pyldap was incorporated into
Looks complete to me