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

Calculating dependencies ... done!
Dependency resolution took 1.09 s (backtrack: 0/20).

[ebuild  N     ] dev-build/boost-m4-0.4_p20250404::gentoo  43 KiB
[ebuild  N     ] dev-build/b2-5.5.3::gentoo  USE="-examples" 1198 KiB
[ebuild  N     ] media-libs/libmpdclient-2.23-r1::gentoo  USE="-doc -examples -test" 70 KiB
[ebuild  N     ] dev-libs/boost-1.91.0-r2:0/1.91.0::gentoo  USE="bzip2 context icu nls python stacktrace zlib -debug -doc -lzma -mpi -numpy -test -test-full -tools -zstd" PYTHON_TARGETS="python3_14 -python3_12 -python3_13" 199785 KiB
[ebuild  N     ] media-sound/ncmpcpp-0.10.1-r1::gentoo  USE="-clock -outputs -taglib -visualizer" 226 KiB

Total: 5 packages (5 new), Size of downloads: 201320 KiB

The following USE changes are necessary to proceed:
 (see "package.use" in the portage(5) man page for more details)
# required by media-sound/ncmpcpp-0.10.1-r1::gentoo
# required by =media-sound/ncmpcpp-0.10.1-r1 (argument)
>=dev-libs/boost-1.91.0-r2 icu