bug#65459: completing-read INITIAL-VALUE unaware of COLLECTION and REQUIRE-MATCH

[Stefan Monnier via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

> For using 'completing-read' without INITIAL as argument, do you have a plan of how 
> minibuffer prefilling could be activated and set for use within some specific user
> function? 

I suggested to accept a `setup-function` argument, which would replace the
`minibuffer-with-setup-hook` hack, so instead of

    (completing-read MYPROMPT ... MYINIT-INPUT ...)

with the new API you could do

    (mynew-completing-read MYPROMPT ...
                           (lambda () (insert "MYINIT-INPUT"))
                           ...)

-- Stefan