emerge -vp
These are the packages that would be merged, in order:
Calculating dependencies ... done!
Dependency resolution took 2.00 s (backtrack: 0/20).
[ebuild N ] app-containers/podman-5.8.6::gentoo USE="seccomp -apparmor -btrfs -cron (-selinux) (-systemd) -wrapper" 20129 KiB
[ebuild N ] dev-lang/go-1.27.2:0/1.27.2::gentoo CPU_FLAGS_X86="sse2" 34312 KiB
[ebuild N ] app-containers/containers-common-0.64.2::gentoo 12824 KiB
[ebuild N ] app-containers/netavark-2.1.0::gentoo USE="-debug" 20630 KiB
[ebuild N ] app-containers/containers-storage-1.59.1::gentoo 4499 KiB
[ebuild N ] app-containers/containers-image-5.36.2::gentoo 747 KiB
[ebuild N ] app-containers/conmon-2.2.1::gentoo USE="seccomp (-selinux) (-systemd)" 83 KiB
[ebuild N ] dev-go/go-md2man-2.0.7::gentoo 86 KiB
Total: 8 packages (8 new), Size of downloads: 93306 KiB
* Error: circular dependencies:
(dev-lang/go-1.27.2:0/1.27.2::gentoo, ebuild scheduled for merge) depends on
(dev-lang/go-1.27.2:0/1.27.2::gentoo, ebuild scheduled for merge) (buildtime)
* Note that circular dependencies can often be avoided by temporarily
* disabling USE flags that trigger optional dependencies.
!!! Multiple package instances within a single package slot have been pulled
!!! into the dependency graph, resulting in a slot conflict:
dev-python/packaging:0
(dev-python/packaging-26.3:0/0::gentoo, ebuild scheduled for merge) USE="-test -verify-provenance" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)" pulled in by
>=dev-python/packaging-25.0[python_targets_pypy3_12(-)?,python_targets_python3_12(-)?,python_targets_python3_13(-)?,python_targets_python3_14t(-)?,python_targets_python3_14(-)?,python_targets_python3_15t(-)?,python_targets_python3_15(-)?] required by (dev-python/setuptools-84.0.0:0/0::gentoo, ebuild scheduled for merge) USE="-test" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)"
dev-python/packaging[python_targets_pypy3_12(-)?,python_targets_python3_12(-)?,python_targets_python3_13(-)?,python_targets_python3_14t(-)?,python_targets_python3_14(-)?,python_targets_python3_15t(-)?,python_targets_python3_15(-)?] required by (dev-python/setuptools-scm-10.3.4:0/0::gentoo, ebuild scheduled for merge) USE="-test -verify-provenance" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)"
>=dev-python/packaging-26.2[python_targets_pypy3_12(-)?,python_targets_python3_12(-)?,python_targets_python3_13(-)?,python_targets_python3_14t(-)?,python_targets_python3_14(-)?,python_targets_python3_15t(-)?,python_targets_python3_15(-)?] required by (dev-python/vcs-versioning-2.6.0:0/0::gentoo, ebuild scheduled for merge) USE="-test -verify-provenance" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)"
^^ ^^^^
>=dev-python/packaging-26.0[python_targets_pypy3_12(-)?,python_targets_python3_12(-)?,python_targets_python3_13(-)?,python_targets_python3_14t(-)?,python_targets_python3_14(-)?,python_targets_python3_15t(-)?,python_targets_python3_15(-)?] required by (dev-python/wheel-0.48.0:0/0::gentoo, ebuild scheduled for merge) USE="-test -verify-provenance" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)"
(and 1 more with the same problems)
(dev-python/packaging-26.0:0/0::gentoo, installed) USE="-test -verify-provenance" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t" pulled in by
>=dev-python/packaging-26.0[python_targets_python3_13(-)] required by (dev-python/wheel-0.46.3:0/0::gentoo, installed) USE="-test -verify-provenance" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t"
>=dev-python/packaging-24.2[python_targets_python3_13(-)] required by (dev-python/hatchling-1.29.0:0/0::gentoo, installed) USE="-test" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t"
>=dev-python/packaging-23.2[python_targets_python3_13(-)] required by (dev-python/scikit-build-core-0.12.2:0/0::gentoo, installed) USE="-test -verify-provenance" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_14"
dev-python/packaging[python_targets_python3_13(-)] required by (dev-python/setuptools-scm-9.2.2:0/0::gentoo, installed) USE="-test -verify-provenance" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t"
>=dev-python/packaging-25.0[python_targets_python3_13(-)] required by (dev-python/setuptools-81.0.0:0/0::gentoo, installed) USE="-test" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t"
>=dev-python/packaging-23.2[python_targets_python3_12(-)?,python_targets_python3_13(-)?,python_targets_python3_14t(-)?,python_targets_python3_14(-)?,python_targets_python3_15t(-)?,python_targets_python3_15(-)?] required by (dev-python/pyproject-metadata-0.11.0:0/0::gentoo, installed) USE="-test -verify-provenance" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t"
dev-python/setuptools-scm:0
(dev-python/setuptools-scm-10.3.4:0/0::gentoo, ebuild scheduled for merge) USE="-test -verify-provenance" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)" pulled in by
dev-python/setuptools-scm[python_targets_pypy3_12(-)?,python_targets_python3_12(-)?,python_targets_python3_13(-)?,python_targets_python3_14t(-)?,python_targets_python3_14(-)?,python_targets_python3_15t(-)?,python_targets_python3_15(-)?] required by (dev-python/setuptools-84.0.0:0/0::gentoo, ebuild scheduled for merge) USE="-test" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)"
(dev-python/setuptools-scm-9.2.2:0/0::gentoo, installed) USE="-test -verify-provenance" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t" pulled in by
dev-python/setuptools-scm[python_targets_python3_13(-)] required by (dev-python/setuptools-81.0.0:0/0::gentoo, installed) USE="-test" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t"
>=dev-python/setuptools-scm-8.2.0[python_targets_pypy3_12(-)?,python_targets_python3_12(-)?,python_targets_python3_13(-)?,python_targets_python3_14t(-)?,python_targets_python3_14(-)?,python_targets_python3_15t(-)?,python_targets_python3_15(-)?] required by (dev-python/hatch-vcs-0.5.0:0/0::gentoo, installed) USE="-test" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t"
dev-python/setuptools:0
(dev-python/setuptools-84.0.0:0/0::gentoo, ebuild scheduled for merge) USE="-test" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)" pulled in by
>=dev-python/setuptools-64[python_targets_pypy3_12(-)?,python_targets_python3_12(-)?,python_targets_python3_13(-)?,python_targets_python3_14t(-)?,python_targets_python3_14(-)?,python_targets_python3_15t(-)?,python_targets_python3_15(-)?] required by (dev-python/setuptools-scm-10.3.4:0/0::gentoo, ebuild scheduled for merge) USE="-test -verify-provenance" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)"
dev-python/setuptools[python_targets_pypy3_12(-)?,python_targets_python3_12(-)?,python_targets_python3_13(-)?,python_targets_python3_14t(-)?,python_targets_python3_14(-)?,python_targets_python3_15t(-)?,python_targets_python3_15(-)?] required by (dev-python/vcs-versioning-2.6.0:0/0::gentoo, ebuild scheduled for merge) USE="-test -verify-provenance" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)"
dev-python/setuptools[python_targets_pypy3_12(-)?,python_targets_python3_12(-)?,python_targets_python3_13(-)?,python_targets_python3_14t(-)?,python_targets_python3_14(-)?,python_targets_python3_15t(-)?,python_targets_python3_15(-)?] required by (dev-python/setuptools-scm-10.3.4:0/0::gentoo, ebuild scheduled for merge) USE="-test -verify-provenance" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)"
dev-python/setuptools[python_targets_python3_12(-)?,python_targets_python3_13(-)?,python_targets_python3_14(-)?,python_targets_python3_15(-)?] required by (net-firewall/nftables-1.1.7:0/1::gentoo, ebuild scheduled for merge) USE="gmp json python readline -debug -doc -libedit -static-libs -test -verify-sig -xtables" PYTHON_TARGETS="python3_14 -python3_12 -python3_13 (-python3_15)"
(dev-python/setuptools-81.0.0:0/0::gentoo, installed) USE="-test" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t" pulled in by
>=dev-python/setuptools-64[python_targets_python3_13(-)] required by (dev-python/setuptools-scm-9.2.2:0/0::gentoo, installed) USE="-test -verify-provenance" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t"
dev-python/setuptools[python_targets_python3_13(-)] required by (dev-python/setuptools-scm-9.2.2:0/0::gentoo, installed) USE="-test -verify-provenance" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t"
dev-python/trove-classifiers:0
(dev-python/trove-classifiers-2026.9.21.13:0/0::gentoo, ebuild scheduled for merge) USE="-test -verify-provenance" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)" pulled in by
>=dev-python/trove-classifiers-2024.10.16[python_targets_pypy3_12(-)?,python_targets_python3_12(-)?,python_targets_python3_13(-)?,python_targets_python3_14t(-)?,python_targets_python3_14(-)?,python_targets_python3_15t(-)?,python_targets_python3_15(-)?] required by (dev-python/setuptools-84.0.0:0/0::gentoo, ebuild scheduled for merge) USE="-test" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)"
(dev-python/trove-classifiers-2026.1.14.14:0/0::gentoo, installed) USE="-test -verify-provenance" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t" pulled in by
dev-python/trove-classifiers[python_targets_python3_13(-)] required by (dev-python/hatchling-1.29.0:0/0::gentoo, installed) USE="-test" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t"
>=dev-python/trove-classifiers-2024.10.16[python_targets_python3_13(-)] required by (dev-python/setuptools-81.0.0:0/0::gentoo, installed) USE="-test" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t"
dev-python/wheel:0
(dev-python/wheel-0.48.0:0/0::gentoo, ebuild scheduled for merge) USE="-test -verify-provenance" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)" pulled in by
>=dev-python/wheel-0.45.1[python_targets_pypy3_12(-)?,python_targets_python3_12(-)?,python_targets_python3_13(-)?,python_targets_python3_14t(-)?,python_targets_python3_14(-)?,python_targets_python3_15t(-)?,python_targets_python3_15(-)?] required by (dev-python/setuptools-84.0.0:0/0::gentoo, ebuild scheduled for merge) USE="-test" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)"
(dev-python/wheel-0.46.3:0/0::gentoo, installed) USE="-test -verify-provenance" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t" pulled in by
>=dev-python/wheel-0.45.1[python_targets_python3_13(-)] required by (dev-python/setuptools-81.0.0:0/0::gentoo, installed) USE="-test" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t"
dev-python/platformdirs:0
(dev-python/platformdirs-4.13.5:0/0::gentoo, ebuild scheduled for merge) USE="-test -verify-provenance" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)" pulled in by
>=dev-python/platformdirs-4.4.0[python_targets_pypy3_12(-)?,python_targets_python3_12(-)?,python_targets_python3_13(-)?,python_targets_python3_14t(-)?,python_targets_python3_14(-)?,python_targets_python3_15t(-)?,python_targets_python3_15(-)?] required by (dev-python/setuptools-84.0.0:0/0::gentoo, ebuild scheduled for merge) USE="-test" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)"
(dev-python/platformdirs-4.9.4:0/0::gentoo, installed) USE="-test -verify-provenance" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t" pulled in by
>=dev-python/platformdirs-4.4.0[python_targets_python3_13(-)] required by (dev-python/setuptools-81.0.0:0/0::gentoo, installed) USE="-test" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t"
dev-python/more-itertools:0
(dev-python/more-itertools-11.2.1:0/0::gentoo, ebuild scheduled for merge) USE="-doc" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)" pulled in by
>=dev-python/more-itertools-0.12.0-r1[python_targets_pypy3_12(-)?,python_targets_python3_12(-)?,python_targets_python3_13(-)?,python_targets_python3_14t(-)?,python_targets_python3_14(-)?,python_targets_python3_15t(-)?,python_targets_python3_15(-)?] required by (dev-python/jaraco-functools-4.6.0:0/0::gentoo, ebuild scheduled for merge) USE="-test" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)"
>=dev-python/more-itertools-10.8.0[python_targets_pypy3_12(-)?,python_targets_python3_12(-)?,python_targets_python3_13(-)?,python_targets_python3_14t(-)?,python_targets_python3_14(-)?,python_targets_python3_15t(-)?,python_targets_python3_15(-)?] required by (dev-python/setuptools-84.0.0:0/0::gentoo, ebuild scheduled for merge) USE="-test" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)"
(dev-python/more-itertools-10.8.0:0/0::gentoo, installed) USE="-doc" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t" pulled in by
>=dev-python/more-itertools-10.8.0[python_targets_python3_13(-)] required by (dev-python/setuptools-81.0.0:0/0::gentoo, installed) USE="-test" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t"
>=dev-python/more-itertools-0.12.0-r1[python_targets_python3_13(-)] required by (dev-python/jaraco-functools-4.4.0:0/0::gentoo, installed) USE="-test" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t"
dev-python/jaraco-text:0
(dev-python/jaraco-text-4.3.0:0/0::gentoo, ebuild scheduled for merge) USE="-test" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)" pulled in by
>=dev-python/jaraco-text-4.0.0[python_targets_pypy3_12(-)?,python_targets_python3_12(-)?,python_targets_python3_13(-)?,python_targets_python3_14t(-)?,python_targets_python3_14(-)?,python_targets_python3_15t(-)?,python_targets_python3_15(-)?] required by (dev-python/setuptools-84.0.0:0/0::gentoo, ebuild scheduled for merge) USE="-test" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)"
(dev-python/jaraco-text-4.2.0:0/0::gentoo, installed) USE="-test" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t" pulled in by
>=dev-python/jaraco-text-4.0.0[python_targets_python3_13(-)] required by (dev-python/setuptools-81.0.0:0/0::gentoo, installed) USE="-test" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t"
dev-python/jaraco-functools:0
(dev-python/jaraco-functools-4.6.0:0/0::gentoo, ebuild scheduled for merge) USE="-test" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)" pulled in by
>=dev-python/jaraco-functools-3.5.0-r1[python_targets_pypy3_12(-)?,python_targets_python3_12(-)?,python_targets_python3_13(-)?,python_targets_python3_14t(-)?,python_targets_python3_14(-)?,python_targets_python3_15t(-)?,python_targets_python3_15(-)?] required by (dev-python/jaraco-text-4.3.0:0/0::gentoo, ebuild scheduled for merge) USE="-test" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)"
>=dev-python/jaraco-functools-4.4.0[python_targets_pypy3_12(-)?,python_targets_python3_12(-)?,python_targets_python3_13(-)?,python_targets_python3_14t(-)?,python_targets_python3_14(-)?,python_targets_python3_15t(-)?,python_targets_python3_15(-)?] required by (dev-python/setuptools-84.0.0:0/0::gentoo, ebuild scheduled for merge) USE="-test" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)"
(dev-python/jaraco-functools-4.4.0:0/0::gentoo, installed) USE="-test" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t" pulled in by
>=dev-python/jaraco-functools-4.4.0[python_targets_python3_13(-)] required by (dev-python/setuptools-81.0.0:0/0::gentoo, installed) USE="-test" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t"
>=dev-python/jaraco-functools-3.5.0-r1[python_targets_python3_12(-)?,python_targets_python3_13(-)?,python_targets_python3_14t(-)?,python_targets_python3_14(-)?,python_targets_python3_15t(-)?,python_targets_python3_15(-)?] required by (dev-python/jaraco-text-4.2.0:0/0::gentoo, installed) USE="-test" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t"
dev-python/jaraco-context:0
(dev-python/jaraco-context-6.1.2:0/0::gentoo, ebuild scheduled for merge) USE="-test" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)" pulled in by
>=dev-python/jaraco-context-4.1.1-r1[python_targets_pypy3_12(-)?,python_targets_python3_12(-)?,python_targets_python3_13(-)?,python_targets_python3_14t(-)?,python_targets_python3_14(-)?,python_targets_python3_15t(-)?,python_targets_python3_15(-)?] required by (dev-python/jaraco-text-4.3.0:0/0::gentoo, ebuild scheduled for merge) USE="-test" PYTHON_TARGETS="python3_14 -pypy3_12 -python3_12 -python3_13 -python3_14t (-python3_15) (-python3_15t)"
(dev-python/jaraco-context-6.1.1:0/0::gentoo, installed) USE="-test" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t" pulled in by
>=dev-python/jaraco-context-4.1.1-r1[python_targets_python3_12(-)?,python_targets_python3_13(-)?,python_targets_python3_14t(-)?,python_targets_python3_14(-)?,python_targets_python3_15t(-)?,python_targets_python3_15(-)?] required by (dev-python/jaraco-text-4.2.0:0/0::gentoo, installed) USE="-test" PYTHON_TARGETS="python3_13 -pypy3_11 -python3_11 -python3_12 -python3_13t -python3_14 -python3_14t"
NOTE: Use the '--verbose-conflicts' option to display parents omitted above
It may be possible to solve this problem by using package.mask to
prevent one of those packages from being selected. However, it is also
possible that conflicting dependencies exist such that they are
impossible to satisfy simultaneously. If such a conflict exists in
the dependencies of two different packages, then those packages can
not be installed simultaneously.
For more information, see MASKED PACKAGES section in the emerge man
page or refer to the Gentoo Handbook.
The following USE changes are necessary to proceed:
(see "package.use" in the portage(5) man page for more details)
# required by app-containers/containers-common-0.64.2::gentoo
# required by app-containers/podman-5.8.6::gentoo
# required by =app-containers/podman-5.8.6 (argument)
>=net-firewall/iptables-1.8.13 nftables
* In order to avoid wasting time, backtracking has terminated early
* due to the above autounmask change(s). The --autounmask-backtrack=y
* option can be used to force further backtracking, but there is no
* guarantee that it will produce a solution.