Error message needed when enabling drawtext filter without libfreetype

[Sebastian]

It would be really helpful if the configure script would issue an error message when trying to do "--enable-filter=drawtext" without adding "--enable-libfreetype". At the moment, there is no error message, and the drawtext filter doesn't get enabled.

The documentation of the drawtext filter does mention then libfreetype is needed - but it would be much more helpful if the configure script would do this check. Otherwise one would have no idea why the filter silently refuses to enable with no error message.

[Carl Eugen Hoyos]

Afaict, this is not how FFmpeg's configure script works:
--enable-filter=drawtext normally has no meaning because it is the default (drawtext will be enabled if the dependencies are fulfilled and it was not disabled), but since drawtext depends on an external library (like the flashsv decoder or the matroska demuxer), it will only be compiled if --enable-libfreetype was added as an option.

Note that the following works as expected / is needed if you want the drawtext filter:
$ ./configure --disable-filters --enable-libfreetype --enable-filter=drawtext

[ill]

I see. Would it be possible to change the error message when drawtext is used but not able to run to alert the user that the freetype option is needed when configuring?