All mesa-18* ebuilds are missing LLVM_MAX_SLOT. It is used by llvm_pkg_setup(). Without it mesa can try to link with a newer llvm slot than specified by LLVM_DEPSTR.
The bug has been closed via the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=e627e1dc0b1ee23bdd73de91269ba81eeef3c2b1 commit e627e1dc0b1ee23bdd73de91269ba81eeef3c2b1 Author: Matt Turner <mattst88@gentoo.org> AuthorDate: 2018-07-04 14:28:48 +0000 Commit: Matt Turner <mattst88@gentoo.org> CommitDate: 2018-07-04 14:28:55 +0000 media-libs/mesa: Define LLVM_MAX_SLOT Closes: https://bugs.gentoo.org/658406 media-libs/mesa/mesa-18.1.3.ebuild | 1 + 1 file changed, 1 insertion(+)