Phantom can be catched into a boat

I don't think this is a bug. All mobs can travel in boats, even hostile ones.

No. You can't get horse into boat. Enderdragon and bat also can't be catched into boat. Another exception is wither and squid.

OK, but the phantom being able to go in a boat could still be intended behaviour. Are you thinking that flying mobs aren't allowed to be in boats? Because parrots are, so it's not that.

The only way this would be a bug is if the changelog explicitly said 'Phantoms cannot travel in boats'. The changelog does not say this.

@@unknown I will change your sentence a bit: The only way this would be a feature is if changelog explicitly said 'Phantoms can travel in boats'. The changelog does not say this. =P
I don't know if it is intended or bug. Devs will decide if phantoms should be catchable by boats or not.

Their original statement was correct; there was no need to change it. And the article on 18w07a, written by a dev, does not explicitly make any note of the behavior you are expecting. Therefore, until further details are given, this can only be assumed to be the intended behavior.

This is a bug tracker. Not a discussion forum. The devs will decide whether this is WAI.

Also affect the cod, salmon and puffer fish.

@@unknown: separate ticket, please.

This ticket is invalid. Phantoms with a small enough hitbox can be caught in a boat, and phantoms with big enough hitboxes cannot enter a boat. The only criteria for boat passengers so far is that squids cannot enter them (for obvious reasons), and mobs that are too large cannot enter them. A small enough phantom does not fit either of these criteria, therefore it can enter a boat as expected.