// Don't write back fields we aren't changing. See issue #14855.
			rhs := rhs.(*ir.SliceExpr)
			i, j, k := rhs.Low, rhs.High, rhs.Max
			if i != nil && (i.Op() == ir.OLITERAL && i.Val().Kind() == constant.Int && ir.Int64Val(i) == 0) {
				// [0:...] is the same as [:...]
				i = nil
			}
			// TODO: detect defaults for len/cap also.