Re: Merging feature/android

[Eli Zaretskii <eliz@gnu.org>]

> From: Po Lu <luangruo@yahoo.com>
> Cc: emacs-devel@gnu.org,  eggert@cs.ucla.edu
> Date: Fri, 03 Mar 2023 17:51:08 +0800
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> From: Po Lu <luangruo@yahoo.com>
> >> Cc: emacs-devel@gnu.org,  eggert@cs.ucla.edu
> >> Date: Fri, 03 Mar 2023 16:03:38 +0800
> >> 
> >> Eli Zaretskii <eliz@gnu.org> writes:
> >> 
> >> > If not, please explain more, because I don't think I understand what
> >> > you say above.
> >> 
> >> I was saying that the HarfBuzz check currently doesn't show an error
> >> when it is enabled with ``--with-harfbuzz'' and HarfBuzz is not found.
> >
> > That's strange, because image libraries use the same OPTION_DEFAULT_ON
> > way, and I definitely remember seeing an error message when I used the
> > "--with-gif" option and the library wasn't available.  The message
> > suggested using ifavailable instead.
> >
> >> The reason is precisely that the option doesn't default to ifavailable;
> >> as a result, configure cannot tell apart the two cases where
> >> $with_harfbuzz is specified on the command line, and when it is simply
> >> set to yes as its default value.  That's why ifavailable is required.
> >
> > Do you see the same with image libraries?
> 
> Image libraries default to being on, while also accepting
> ``ifavailable'' as an option.  The default values of the options for the
> common image libraries is not ``ifavailable'', because we want configure
> to error out by default if the library is not present.

So why shouldn't it be the same with modules?  Don't we want the user
to be aware that modules support will be absent?