>>> Failed to emerge sys-devel/clang-11.0.0, Log file:

>>> '/var/tmp/portage/sys-devel/clang-11.0.0/temp/build.log'

• Messages for package sys-devel/clang-11.0.0:

• ERROR: sys-devel/clang-11.0.0::llvm-kit failed (compile phase):
• ninja -v -j4 -l0 distribution failed
• Call stack:
• ebuild.sh, line 93: Called src_compile
• environment, line 4014: Called multilib-minimal_src_compile
• environment, line 2612: Called multilib_foreach_abi 'multilib-minimal_abi_src_compile'
• environment, line 2882: Called multibuild_foreach_variant '_multilib_multibuild_wrapper' 'multilib-minimal_abi_src_compile'
• environment, line 2547: Called _multibuild_run '_multilib_multibuild_wrapper' 'multilib-minimal_abi_src_compile'
• environment, line 2545: Called _multilib_multibuild_wrapper 'multilib-minimal_abi_src_compile'
• environment, line 596: Called multilib-minimal_abi_src_compile
• environment, line 2606: Called multilib_src_compile
• environment, line 3094: Called cmake_build 'distribution'
• environment, line 1273: Called eninja 'distribution'
• environment, line 1728: Called die
• The specific snippet of code:
• "$@" || die "${nonfatal_args[@]}" "${*} failed"

it seems to require multilib, which Funtoo doesn't have.