[dns-operations] RES_USE_INET6 and the inet6 resolver option

[Viktor Dukhovni]

> On Feb 8, 2019, at 5:04 AM, Florian Weimer <fweimer at redhat.com> wrote:
> 
> The result is that many applications simply break if this option is
> active (instead of being able to use IPv6 without changes, as may have
> been the intent), so it does not seem particularly useful to have this
> option available.  Since it also results in some awkward layering
> violations (why would host name lookups in an LDAP database care about
> resolv.conf settings?), I've deprecated it a while back and think it's
> now time to remove it.
> 
> Comments?  Is anyone using this?

Eliminate with prejudice.  The interface is unsound and unsafe since
the effects can leak across module boundaries surprising co-resident
code that neither asked for, nor expected the change in semantics.
And unless the effect is thread-local, it is fragile in multi-threaded
applications that attempt to make the side-effect temporary around
particular lookups.

-- 
	Viktor.