Re: Merging feature/android

[Po Lu <luangruo@yahoo.com>]

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.

Thanks.