Gentoo's Bugzilla –
Attachment 421092 Details for
Bug 570102media-libs/iulib-0.4 : imglib/imgops.cc:136:40: error: redeclaration of 'template<class T, class V> void iulib::addscaled(colib::narray<T>&, colib::narray<T>&, V, int, int)' may not have default arguments [-fpermissive]