I don't know describe this bug or if it's a bug related with the libclc. Sorry and thank you! emerge -avu =sys-devel/llvm-3.7.1-r2:0/3.7.1::gentoo --backtrack=30 These are the packages that would be merged, in order: Calculating dependencies... done! [ebuild U ] sys-devel/llvm-3.7.1-r2:0/3.7.1::gentoo [3.5.0:0/3.5::gentoo] USE="libffi ncurses python static-analyzer xml -clang* -debug -doc -gold -libedit -lldb% -multitarget -ocaml {-test}" PYTHON_TARGETS="python2_7 (-pypy%)" VIDEO_CARDS="-radeon" 14288 KiB Total: 1 package (1 upgrade), Size of downloads: 14288 KiB !!! Multiple package instances within a single package slot have been pulled !!! into the dependency graph, resulting in a slot conflict: sys-devel/llvm:0 (sys-devel/llvm-3.7.1-r2:0/3.7.1::gentoo, ebuild scheduled for merge) pulled in by =sys-devel/llvm-3.7.1-r2:0/3.7.1::gentoo (Argument) (sys-devel/llvm-3.5.0:0/3.5::gentoo, installed) pulled in by >=sys-devel/llvm-3.4.2:0/3.5=[abi_x86_64(-)] required by (media-libs/mesa-11.0.6:0/0::gentoo, installed) ^^^^^^^ ~sys-devel/llvm-3.5.0[clang(-),debug=,multitarget?,python?,static-analyzer,abi_x86_32(-)?,abi_x86_64(-)?,abi_x86_x32(-)?,abi_mips_n32(-)?,abi_mips_n64(-)?,abi_mips_o32(-)?,abi_ppc_32(-)?,abi_ppc_64(-)?,abi_s390_32(-)?,abi_s390_64(-)?] required by (sys-devel/clang-3.5.0-r100:0/3.5::gentoo, installed) ^ ^^^^^ <sys-devel/llvm-3.6 required by (dev-libs/libclc-0.0.1_pre20141027:0/0::gentoo, installed) ^ ^^^ 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.
(In reply to Luis Ferreira from comment #0) > <sys-devel/llvm-3.6 required by > (dev-libs/libclc-0.0.1_pre20141027:0/0::gentoo, installed) Yep, the current stable version of libclc is preventing the llvm upgrade. Newer versions do not have this problem, so let's see what the X11 teams thinks about stabilising it.
As per bug 586278 comment 1, there is a stabilization bug for that package already. Unless there are urgent issues like security bugs or serious breakage, all x11 stabilization will happen in batches. *** This bug has been marked as a duplicate of bug 579266 ***