For the love of all that is Nitro+, We should have a tag for stuff like that. Hmmm. Is a bayonette still one considered one even if the blade isn't on the front of the rifle? Luckily, Danby is ripe with gun nuts who would totally now the answer to this question.
A Gun-knife (or Knife-gun as they are more commonly called) exists. In fact there is a whole, though small, sub class of collectible firearms. There were even gun swords and gun silverware. In the 18th century there was a fad for building guns into all kinds of things but edged weapons were the most common. The idea was, when your ammo ran out you still had a weapon. This would be a completely legit tag to use. A rifle with a bayonet is a different thing. The "knife" (bayonet) is added to the rifle as more or less an afterthought or accessory and not bilt in like the knife-guns. There are a few weapons which do have their bayonet permanently attached bit almost all of them are of the "spike" type and not bladed like the traditional bayonet so a rifle with a bayonet mounted would not count as a knife gun.