[ebuild   R   ] sys-devel/gcc-4.9.3  USE="cxx fortran gcj (multilib) nls nptl openmp sanitize vtv (-altivec) (-awt) -cilk -debug -doc (-fixed-point) -go -graphite (-hardened) (-libssp) -multislot -nopie -nossp -objc -objc++ -objc-gc -regression-test -vanilla" 
[blocks B     ] <sys-devel/gcc-4.9 ("<sys-devel/gcc-4.9" is blocking sys-devel/gcc-4.9.3)

 * Error: The above package list contains packages which cannot be
 * installed at the same time on the same system.

  (sys-devel/gcc-4.9.3:4.9.3/4.9.3::gentoo, ebuild scheduled for merge) pulled in by
    sys-devel/gcc:4.9.3

  (sys-devel/gcc-4.7.4:4.7.4/4.7.4::gentoo, installed) pulled in by
    sys-devel/gcc:4.7.4 required by @selected