[FFmpeg-devel] [PATCH] configure: require pkg-config for libvorbis

[Reimar Döffinger]

On 04.07.2017, at 14:03, Ricardo Constantino <wiiaboo at gmail.com> wrote:

> On 4 July 2017 at 07:54, Reimar Döffinger <Reimar.Doeffinger at gmx.de> wrote:
>> On 30.06.2017, at 20:06, Ricardo Constantino <wiiaboo at gmail.com> wrote:
>> 
>>> libvorbis comes with pkg-config files since at least v1.0.1, way back
>>> in 2003.
>>> 
>>> The extra check is needed for shared builds, as the pkg-config file
>>> for vorbisenc doesn't include vorbis and ogg if --static isn't used.
>> 
>> If you still manually add -lvorbis that IMHO defeats the purpose of using pkg-config the first place.
>> I don't know if our actual code using vorbisenc depend on libvorbis and libogg, but if it does then the flags for all 3 would have to be requested via pkg-config.
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> 
> If the first pkg-config test fails (in case of shared), I test with
> check_pkg_config with those extralibs added and then add them if it
> worked.
> It doesn't defeat the purpose because pkg-config is not just for the
> -l flags. In my usecase I need both -I and -L flags for the proper
> installation too but I didn't build with shared libraries so I never
> noticed this before.

Seems you found a solution, and "defeats the purpose" was exaggerated, but
be point of pkg-config is to not make assumptions on where libraries are,
and by just adding -lvorbis you hardcoded exactly such an assumption:
that libvorbis is in the same place as libvorbisenc.
Checking like your latest patch ensures that both get their proper -L options.