"Zack Weinberg" <zack@owlfolio.org> writes:

> ```
> (declare-function ansi-color-apply-on-region "ansi-color"
>                   (begin end &optional preserve-sequences))
>
> (declare-function dired-get-marked-files "dired"
>                   (&optional localp arg filter distinguish-one-marked error))
>
> (eval-when-compile
>   (check-declare-file byte-compile-current-file))
>
> (defun colorize-buffer ()
>   (interactive)
>   (ansi-color-apply-on-region (point-min) (point-max)))
>
> (defun find-marked-files ()
>   (interactive)
>   (mapc 'find-file (dired-get-marked-files)))
> ```
>
> If you visit this file in emacs -Q and then invoke check-declare-file on
> it interactively, check-declare-file generates no warnings, which is
> correct.  However, if you invoke `emacs -Q --batch -f batch-byte-compile
> test.el` from the shell, you will get this output:
>
> ```
> uncompressing ansi-color.el.gz...
> uncompressing ansi-color.el.gz...done
> uncompressing dired.el.gz...
> uncompressing dired.el.gz...done
>
> In end of data:
> test.el:13:4: Warning: the function ‘ansi-color-apply-on-region’ might
> not be
>     defined at runtime.
> ```
>
> "The function ‘...’ might not be defined" is the phrase used by
> byte-compile-warn-about-unresolved-functions.  It's not a check-declare
> diagnostic.

Indeed - so we have an interference between byte compilation,
`eval-when-compile' and `check-declare-file'.  This seems to help and
might (?) be a good thing to do anyway: