Ssh – How to edit command completion for ssh on bash

(I've asked this question regarding zsh, but I also use bash and would find it useful there too–as I'm guessing many others would too since bash has many more users than zsh.)

I'd like to set up command completion on bash to display host names after I type

ssh [TAB]

taking the names out of my .ssh/config file (and preferably from known_hosts and /etc/hosts and anywhere else that makes sense) and presenting one single list.

It does some of this currently, but

1. it doesn't use .ssh/config at all
2. it requires a username first, even though using .ssh/config makes typing usernames unnecessary
3. it presents multiple lists (probably one from known_hosts and another from /etc/hosts, but I haven't verified that)

So I want to be include known usernames as well as known hostnames in the (preferably single) list after typing ssh [TAB]

(I'm coming here before Google because 1) it'll result in the answer getting stored here, and 2) it's probably more efficient. If no one else answers, I'll hunt down the answer.)