$ sudo emerge -aqv @preserved-rebuild [ebuild N ] net-libs/libnsl-1.1.0-r3 ABI_X86="32 (64) (-x32)" [ebuild N ] app-text/opensp-1.5.2-r3 USE="nls -doc -static-libs {-test}" [ebuild R ] app-text/openjade-1.3.2-r7 USE="-static-libs" [blocks B ] <sys-libs/glibc-2.26 ("<sys-libs/glibc-2.26" is blocking net-libs/libnsl-1.1.0-r3) * Error: The above package list contains packages which cannot be * installed at the same time on the same system. (net-libs/libnsl-1.1.0-r3:0/2::gentoo, ebuild scheduled for merge) pulled in by net-libs/libnsl:0= required by (app-text/opensp-1.5.2-r3:0/0::gentoo, ebuild scheduled for merge) (sys-libs/glibc-2.25-r9:2.2/2.2::gentoo, installed) pulled in by sys-libs/glibc:2.2 required by @selected
Portage is simply trying to tell you that it can not install libnsl while you have an older version than glibc-2.26 installed. Do a regular world upgrade.
I see. From the ebuild: RDEPEND="${DEPEND} !<sys-libs/glibc-2.26 " The [blocks B] message left out the !