Use std::underlying_type_t
Use std::underlying_type_t

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