$ emerge --info=media-libs/opencv-4.12.0-r1::gentoo && emerge -p =media-libs/opencv-4.12.0-r1::gentoo;

$ emerge --info=media-libsopencv-4.12.0-r1::gentoo && emerge -p =media-libsopencv-4.12.0-r1::gentoo;

$ emerge --info=media-libs/opencv-4.12.0-r1::gentoo && emerge -p =media-libs/opencv-4.12.0-r1::gentoo
usage: emerge [--depclean] [--list-sets] [--help] [--metadata] [--config]
              [--clean] [--prune] [--check-news] [--search] [--version]
              [--regen] [--moo] [--unmerge] [--info] [--rage-clean] [--sync]
              [--alphabetical] [--ask-enter-invalid] [--buildpkgonly]
              [--changed-use] [--columns] [--debug] [--digest] [--emptytree]
              [--verbose-conflicts] [--fetchonly] [--fetch-all-uri]
              [--ignore-default-opts] [--noconfmem] [--newrepo] [--newuse]
              [--nodeps] [--noreplace] [--nospinner] [--oneshot] [--onlydeps]
              [--pretend] [--quiet-repo-display] [--quiet-unmerge-warn]
              [--resume] [--searchdesc] [--skipfirst] [--tree]
              [--unordered-display] [--update] [--update-if-installed] [-1]
              [-B] [-c] [-C] [-d] [-e] [-f] [-F] [-h] [-n] [-N] [-o] [-O] [-p]
              [-P] [-r] [-s] [-S] [-t] [-u] [-U] [-V] [--cols] [--skip-first]
              [--alert {True,y,n}] [--ask {True,y,n}]
              [--autounmask {True,y,n}] [--autounmask-backtrack {y,n}]
              [--autounmask-continue {True,y,n}]
              [--autounmask-only {True,y,n}] [--autounmask-license {y,n}]
              [--autounmask-unrestricted-atoms {True,y,n}]
              [--autounmask-use {y,n}] [--autounmask-keep-keywords {True,y,n}]
              [--autounmask-keep-masks {True,y,n}]
              [--autounmask-write {True,y,n}]
              [--accept-properties ACCEPT_PROPERTIES]
              [--accept-restrict ACCEPT_RESTRICT] [--backtrack BACKTRACK]
              [--binpkg-changed-deps {True,y,n}] [--buildpkg {True,y,n}]
              [--buildpkg-exclude BUILDPKG_EXCLUDE]
              [--changed-deps {True,y,n}] [--changed-deps-report {True,y,n}]
              [--changed-slot {True,y,n}] [--config-root CONFIG_ROOT]
              [--color {y,n}] [--complete-graph {True,y,n}]
              [--complete-graph-if-new-use {y,n}]
              [--complete-graph-if-new-ver {y,n}] [--deep DEEP]
              [--depclean-lib-check {True,y,n}] [--deselect {True,y,n}]
              [--dynamic-deps {y,n}] [--exclude EXCLUDE]
              [--fail-clean {True,y,n}] [--fuzzy-search {True,y,n}]
              [--ignore-built-slot-operator-deps {y,n}]
              [--ignore-soname-deps {y,n}] [--ignore-world {True,y,n}]
              [--implicit-system-deps {y,n}] [--jobs JOBS]
              [--keep-going {True,y,n}] [--load-average LOAD_AVERAGE]
              [--misspell-suggestions {y,n}] [--with-bdeps {y,n}]
              [--with-bdeps-auto {y,n}] [--reinstall {changed-use}]
              [--reinstall-atoms REINSTALL_ATOMS]
              [--binpkg-respect-use {True,y,n}] [--getbinpkg {True,y,n}]
              [--getbinpkgonly {True,y,n}] [--usepkg-exclude USEPKG_EXCLUDE]
              [--onlydeps-with-ideps {True,y,n}]
              [--onlydeps-with-rdeps {True,y,n}]
              [--rebuild-exclude REBUILD_EXCLUDE]
              [--rebuild-ignore REBUILD_IGNORE] [--package-moves {True,y,n}]
              [--prefix PREFIX] [--pkg-format PKG_FORMAT]
              [--quickpkg-direct {y,n}]
              [--quickpkg-direct-root QUICKPKG_DIRECT_ROOT]
              [--quiet {True,y,n}] [--quiet-build {True,y,n}]
              [--quiet-fail {True,y,n}] [--read-news {True,y,n}]
              [--rebuild-if-new-slot {True,y,n}]
              [--rebuild-if-new-rev {True,y,n}]
              [--rebuild-if-new-ver {True,y,n}]
              [--rebuild-if-unbuilt {True,y,n}]
              [--rebuilt-binaries {True,y,n}]
              [--rebuilt-binaries-timestamp REBUILT_BINARIES_TIMESTAMP]
              [--regex-search-auto {y,n}] [--root ROOT]
              [--root-deps {True,rdeps}] [--search-index {y,n}]
              [--search-similarity SEARCH_SIMILARITY] [--select {True,y,n}]
              [--selective {True,y,n}] [--sync-submodule {glsa,news,profiles}]
              [--sysroot SYSROOT] [--use-ebuild-visibility {True,y,n}]
              [--useoldpkg-atoms USEOLDPKG_ATOMS] [--usepkg {True,y,n}]
              [--usepkgonly {True,y,n}] [--usepkg-exclude-live {True,y,n}]
              [--verbose {True,y,n}] [--verbose-slot-rebuilds {True,y,n}]
              [--with-test-deps {True,y,n}]
              [positional_args ...]
emerge: error: argument --info: ignored explicit argument 'media-libs/opencv-4.12.0-r1::gentoo'