The compiler check in the ebuild verifies if GCC is >= 4.6, but it won't account for Clang, so when trying to to build with Clang you get: * ERROR: kde-apps/akonadi-1.13.1_pre20160203-r1::gentoo failed (pretend phase): * Sorry, but gcc-4.6 and earlier won't work (see bug #520102).
Thanks, fixed in git. https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=4817ac5148e37411f1f31f822eb5765fb5b34127