bug#69120: Spurious "function is not known to be defined" if defined in `use-package` body

[Eli Zaretskii <eliz@gnu.org>]

> From: Konstantin Kharlamov <Hi-Angel@yandex.ru>
> Cc: 69120@debbugs.gnu.org
> Date: Wed, 14 Feb 2024 19:10:54 +0300
> 
> On Wed, 2024-02-14 at 18:07 +0200, Eli Zaretskii wrote:
> > > From: Konstantin Kharlamov <Hi-Angel@yandex.ru>
> > > Cc: 69120@debbugs.gnu.org
> > > Date: Wed, 14 Feb 2024 18:28:15 +0300
> > >
> > > > >     test.el:6:4: Warning: the function ‘hello’ is not known to
> > > > > be
> > > > > defined.
> > > >
> > > > What do you get if you macro-expand your code?
> > >
> > > Wrapping the above code to a `(macroexpand …)` gives a:
> > >
> > >    "hello"
> > >    nil
> >
> > You need to quote the form you pass to macroexpand, to get the
> > expansion, I think.
> 
> Oh indeed you're right!
> 
> It gives me the following:
> 
> (progn (defvar use-package--warning196 #'(lambda (keyword err) (let ((msg (format "%s/%s: %s" 'prog-mode keyword (error-message-string err)))) (display-warning 'use-package msg :error)))) (condition-case-unless-debug err (progn (condition-case-unless-debug err (progn (defun hello nil (print "hello")) (hello)) (error (funcall use-package--warning196 :init err))) (if (not (require 'prog-mode nil t)) (display-warning 'use-package (format "Cannot load %s" 'prog-mode) :error))) (error (funcall use-package--warning196 :catch err))))

And that doesn't explain the warning?