The resolution to bug 327575 adds a new USE flag for the sys-devel/clang ebuild system-cxx-headers, however only the 2.7-r2 ebuild had this flag added to IUSE. The -9999 (svn) ebuild does not, causing it to be ignored: * QA Notice: USE Flag 'system-cxx-headers' not in IUSE for sys-devel/clang-9999 * If clang++ fails to find C++ headers on your system, * you can remerge clang with USE=system-cxx-headers to use C++ headers * from the active gcc profile I added it to the IUSE decl in my local tree, that seems to be all that is needed. Reproducible: Always
Indeed, thanks for spotting and reporting it! Fixed in CVS