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

Calculating dependencies ... done!
Dependency resolution took 1.59 s (backtrack: 0/20).

[ebuild   R    ] sys-libs/zlib-1.3.2-r1:0/1::gentoo  USE="minizip* -static-libs -verify-sig" 1290 KiB
[ebuild  N     ] dev-libs/cxxtools-3.0-r4::gentoo  USE="-test" 653 KiB
[ebuild  N     ] virtual/minizip-1.3.1:0/1::gentoo  USE="-static-libs" 0 KiB
[ebuild  N     ] app-arch/zip-3.0_p16::gentoo  USE="bzip2 crypt (unicode) -natspec" 1270 KiB
[ebuild  N     ] dev-libs/tntnet-3.0::gentoo  USE="ssl -doc -gnutls -server -test" 859 KiB

Total: 5 packages (4 new, 1 reinstall), Size of downloads: 4070 KiB

The following USE changes are necessary to proceed:
 (see "package.use" in the portage(5) man page for more details)
# required by virtual/minizip-1.3.1::gentoo[-static-libs]
# required by dev-libs/tntnet-3.0::gentoo
# required by =dev-libs/tntnet-3.0 (argument)
>=sys-libs/zlib-1.3.2-r1 minizip