Currently, the output is not very helpful, for example this: !!! The ebuild selected to satisfy ">=net-libs/webkit-gtk-1.6.1:2" has unmet requirements. - net-libs/webkit-gtk-2.2.5-r200::gentoo USE="egl geoloc gles2 gstreamer introspection jit opengl spell webgl (-aqua) -coverage -debug -libsecret -test" The following REQUIRED_USE flag constraints are unsatisfied: webgl? ( exactly-one-of ( gles2 opengl ) ) The above constraints are a subset of the following complete expression: geoloc? ( introspection ) introspection? ( gstreamer ) gles2? ( egl ) webgl? ( exactly-one-of ( gles2 opengl ) ) !webgl? ( at-most-one-of ( gles2 opengl ) ) Maintainers are advised to resolve required_use by default with the base.profile. I trust maintainers to set sane defaults for their package. Improvement to the output could look like following: !!! The ebuild selected to satisfy ">=net-libs/webkit-gtk-1.6.1:2" has unmet requirements. - net-libs/webkit-gtk-2.2.5-r200::gentoo USE="egl geoloc gles2 gstreamer introspection jit opengl spell webgl (-aqua) -coverage -debug -libsecret -test" Affected useflags, (de-)activated by: +webgl: base.profile +gles2: ebuild +opengl: make.conf The following REQUIRED_USE flag constraints are unsatisfied: webgl? ( exactly-one-of ( gles2 opengl ) ) The above constraints are a subset of the following complete expression: geoloc? ( introspection ) introspection? ( gstreamer ) gles2? ( egl ) webgl? ( exactly-one-of ( gles2 opengl ) ) !webgl? ( at-most-one-of ( gles2 opengl ) ) This improves user experience, because now a user know where the conflict results from and this makes it easier to resolve it.