compgen -I (programmable completion as if initial word)

[Stephen Gildea]

I would like these two partially entered commands to complete the
same way:

$ ca<Tab>
$ sudo ca<Tab>

The first completion nicely takes into account any previous
"complete -I" setting (because it is completing the initial
word of a command).

But the second completion relies on a programmable completion,
and in Bash 5.2 it is hard to program the same behavior.  In
particular, the programmed completion cannot easily tell Bash
to obey my -I setting.

I can get _almost_ the same effect by having the "sudo" compspec
run "compgen -c" (generate completions over command names), but
that would ignore my -I setting.

I would like to be able to say "compgen -I" in my compspec and
have Bash generate completions as if this were the initial
word of a command, applying whatever settings it would to an
actual initial word.

 < Stephen