The problem is a REQUIRED_USE in the ebuild, and Python 2.x being the only supported version. That REQUIRED_USE makes emerge fail even when PYTHON_COMPAT_OVERRIDE is set to python3_6. Either Python 2.x needs to be added back, or a version of clang with python 3.x support must be used. As a workaround, I've patched the ebuild to add python3_6 to PYTHON_COMPAT by hand. The actual error from the build log follows. --- build log --- USE=-acl -berkdb -fortran -gdbm -git -libcxx -nls -pcre -ssl -python bootstrap clang internal-glib prefix-stack PKG=sys-devel/clang WARNING: One or more repositories have been ignored due to duplicate profiles/repo_name entries: /cvmfs/sft.cern.ch/lcg/contrib/gentoo/macos/, gentoo_prefix, /cvmfs/sft.cern.ch/lcg/contrib/gentoo/macos/var/db/repos/gentoo overrides /cvmfs/sft.cern.ch/lcg/contrib/gentoo/macos/tmp/var/db/repos/gentoo All profiles/repo_name entries must be unique in order to avoid having duplicates ignored. Set PORTAGE_REPO_DUPLICATE_WARN="0" in /etc/portage/make.conf if you would like to disable this warning. These are the packages that would be merged, in order: !!! Problem resolving dependencies for sys-devel/clang !!! The ebuild selected to satisfy "sys-devel/clang" for /cvmfs/sft.cern.ch/lcg/contrib/gentoo/macos/ has unmet requirements. - sys-devel/clang-6.0.1::gentoo_prefix USE="(prefix) (prefix-guest) static-analyzer -debug -default-compiler-rt -default-libcxx -doc -test -xml (-z3)" LLVM_TARGETS="BPF (X86) -AArch64 -AMDGPU -ARM -Hexagon -Lanai -MSP430 -Mips -NVPTX -PowerPC -Sparc -SystemZ -XCore" PYTHON_TARGETS="-python2_7" The following REQUIRED_USE flag constraints are unsatisfied: python_targets_python2_7 The above constraints are a subset of the following complete expression: python_targets_python2_7 any-of ( llvm_targets_AArch64 llvm_targets_AMDGPU llvm_targets_ARM llvm_targets_BPF llvm_targets_Hexagon llvm_targets_Lanai llvm_targets_Mips llvm_targets_MSP430 llvm_targets_NVPTX llvm_targets_PowerPC llvm_targets_Sparc llvm_targets_SystemZ llvm_targets_X86 llvm_targets_XCore ) Hmmmm, I was already afraid of this to happen. Running /cvmfs/sft.cern.ch/lcg/contrib/gentoo/macos/usr/bin/bash /Users/jenkins/bin/bootstrap-prefix.sh "/cvmfs/sft.cern.ch/lcg/contrib/gentoo/macos" stage3
fixed and confirmed in x86_64-apple-darwin17/20190713
