[FFmpeg-devel] [PATCH 1/4] checkasm/Makefile: add EXTRALIBS-libavformat

[James Almer]

On 3/18/2018 1:06 PM, Paul B Mahol wrote:
> On 3/18/18, James Almer <jamrial at gmail.com> wrote:
>> On 3/18/2018 12:17 PM, Paul B Mahol wrote:
>>> On 3/18/18, James Almer <jamrial at gmail.com> wrote:
>>>> On 3/18/2018 10:40 AM, josh at itanimul.li wrote:
>>>>> From: Josh de Kock <josh at itanimul.li>
>>>>>
>>>>> ---
>>>>>  tests/checkasm/Makefile | 2 +-
>>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/tests/checkasm/Makefile b/tests/checkasm/Makefile
>>>>> index 0520e264e2..ae7e810d25 100644
>>>>> --- a/tests/checkasm/Makefile
>>>>> +++ b/tests/checkasm/Makefile
>>>>> @@ -61,7 +61,7 @@ tests/checkasm/checkasm.o: CFLAGS += -Umain
>>>>>  CHECKASM := tests/checkasm/checkasm$(EXESUF)
>>>>>
>>>>>  $(CHECKASM): $(CHECKASMOBJS) $(FF_STATIC_DEP_LIBS)
>>>>> -	$(LD) $(LDFLAGS) $(LDEXEFLAGS) $(LD_O) $(CHECKASMOBJS)
>>>>> $(FF_STATIC_DEP_LIBS) $(EXTRALIBS-avcodec) $(EXTRALIBS-avfilter)
>>>>> $(EXTRALIBS-avutil) $(EXTRALIBS-swresample) $(EXTRALIBS)
>>>>> +	$(LD) $(LDFLAGS) $(LDEXEFLAGS) $(LD_O) $(CHECKASMOBJS)
>>>>> $(FF_STATIC_DEP_LIBS) $(EXTRALIBS-avcodec) $(EXTRALIBS-avfilter)
>>>>> $(EXTRALIBS-avformat) $(EXTRALIBS-avutil) $(EXTRALIBS-swresample)
>>>>> $(EXTRALIBS)
>>>>
>>>> This is not the correct fix. We currently only need to link to avcodec,
>>>> avfilter and avutil here, which may or may not depend on other fflibs.
>>>> Seeing swresample there already hints that this line got duct tape fixes
>>>> as linking failures popped up. How long until someone gets a linking
>>>> failure pointing to swscale or postproc, seeing avfilter may link to it
>>>> depending on enabled filters, much like it does with avformat?
>>>>
>>>> The *_FFLIBS variables in config.mak list these dependencies per lib,
>>>> and should be used to assemble a proper linking command here.
>>>>
>>>>>
>>>>>  checkasm: $(CHECKASM)
>>>>>
>>>>>
>>>>
>>>> _______________________________________________
>>>> ffmpeg-devel mailing list
>>>> ffmpeg-devel at ffmpeg.org
>>>> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>>>>
>>>
>>> Try patchset without it and than complain instead.
>>
>> I'm not saying it's not needed, I'm saying it's not the correct way to
>> fix the linking failure the following patches would introduce.
> 
> And how do you know that?, without even providing alternative?

I provided an alternative. Look at my comment about the *_FFLIBS
variables. The build system already uses it when linking the libraries
themselves.
The build system has a lot of measures to only build the required
objects and only link the required libraries based on configure time
options. Hardcoding avformat and swresample extralibs for this
executable when avcodec and avfilter may be built without the modules
that require said libraries is doing the exact opposite of that.

Sure, we can commit this as a "temporary" fix, seeing that something
needs to be done in a timely manner so the iterate() api can be
committed, but the result will be that nobody will bother to implement
it right afterwards.