sys-fs/btrfs-progs-0.15-r1 dev-libs/boost-1.34.1-r2 btrfs v0.15 introduces new command "bcp" used for COW (Copy On Write, see http://lwn.net/Articles/284356/) which conflicts with boost's tool "bcp" for extracting subsets of Boost (see http://www.boost.org/doc/libs/1_35_0/tools/bcp/bcp.html) >>> Installing sys-fs/btrfs-progs-0.15-r1 !!! Failed to merge config wrapped(use): ebuild src: sys-fs/btrfs-progs-0.15-r1: Modification was blocked by collision_protect: collision-protect: file(s) already exist: ( file:/usr/bin/bcp ) ony ~ # qfile /usr/bin/bcp dev-libs/boost (/usr/bin/bcp) ^C Reproducible: Always Steps to Reproduce: 1. USE=bcp emerge \>=dev-libs/boost-1.33.1 2. FEATURES=collision-protect emerge >=emerge -vp \>=sys-fs/btrfs-progs-0.15 Actual Results: collision on /usr/bin/bcp Expected Results: one of package should be be patched to use unique names for their utils i.e. boost-bcp or/and cowcp/btrcp and/or contact with btrfs (as I understand they are younger than boost) "bcp" USE-flag disapeared somewhere within dev-libs/boost-1.33.1-r1 and dev-libs/boost-1.34.1-r1, so no workaround except of renaming/overwriting file.
Fixed in btrfs-progs-0.15-r2. I no longer install /usr/bin/bcp. It is not needed for the functioning of btrfs; I may bring it back, renamed, later.