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

Calculating dependencies  ... done!
[ebuild   R    ] sys-devel/gcc-6.4.0-r1:6.4.0::gentoo  USE="cxx debug go hardened (multilib) nls nptl openmp pgo (pie) (ssp) vtv (-altivec) (-awt) -cilk -doc (-fixed-point) -fortran (-gcj) -graphite (-jit) (-libssp) -mpx -objc -objc++ -objc-gc (-pch) -regression-test (-sanitize) -vanilla" 0 KiB
[ebuild   R    ] sys-libs/readline-7.0_p3:0/7::gentoo  USE="-static-libs -utils" ABI_X86="(64) -32 (-x32)" 0 KiB
[ebuild   R   ~] app-portage/emlop-0.1.0_p20180221::moltonel  USE="-debug" 0 KiB
[ebuild   R    ] app-shells/bash-4.4_p12::gentoo  USE="net nls (readline) -afs -bashlogger -examples -mem-scramble -plugins" 0 KiB
[ebuild   R    ] dev-db/postgresql-10.3:10::gentoo  USE="nls pam python readline server ssl threads zlib -doc -kerberos -ldap -libressl -perl (-selinux) -static-libs -systemd -tcl -uuid -xml" PYTHON_SINGLE_TARGET="python3_5 -python2_7 -python3_4 -python3_6" PYTHON_TARGETS="python3_5 -python2_7 -python3_4 -python3_6" 0 KiB

Total: 5 packages (5 reinstalls), Size of downloads: 0 KiB