These are the packages that would be merged, in order:

Calculating dependencies... done!

!!! The ebuild selected to satisfy "net-misc/curl" has unmet requirements.
- net-misc/curl-7.24.0::gentoo USE="gnutls ipv6 ldap nss ssl threads -ares -idn -kerberos -ssh -static-libs -test"

  The following REQUIRED_USE flag constraints are unsatisfied:
    nss? ( !gnutls )

  The above constraints are a subset of the following complete expression:
    threads? ( !ares ) nss? ( !gnutls )

(dependency required by "app-text/poppler-0.16.7[curl]" [ebuild])
(dependency required by "net-print/cups-1.4.8-r1" [ebuild])
(dependency required by "x11-libs/gtk+-2.24.8-r1[cups]" [installed])
(dependency required by "net-irc/xchat-2.8.8-r2[gtk]" [installed])
(dependency required by "@selected" [set])
(dependency required by "@world" [argument])