Use std::underlying_type
Use std::underlying_type

chainer/chainer,keisuke-umezawa/chainer,hvy/chainer,wkentaro/chainer,ktnyt/chainer,chainer/chainer,ktnyt/chainer,ktnyt/chainer,okuta/chainer,chainer/chainer,tkerola/chainer,hvy/chainer,jnishi/chainer,wkentaro/chainer,okuta/chainer,hvy/chainer,jnishi/chainer,keisuke-umezawa/chainer,jnishi/chainer,ktnyt/chainer,jnishi/chainer,niboshi/chainer,niboshi/chainer,hvy/chainer,wkentaro/chainer,okuta/chainer,okuta/chainer,keisuke-umezawa/chainer,niboshi/chainer,keisuke-umezawa/chainer,wkentaro/chainer,chainer/chainer,niboshi/chainer,pfnet/chainer