On Oct 11, 2021, at 15:54, Sriranga Veeraraghavan wrote:
> I am by no means a macports expert, but based on my experience, I think you
> can ignore the warnings. AFAIK, the warnings are telling you the following:
>
> 1. The first message you received regarding ffmpeg indicates that ffmpeg was
> built with modules that are licensed under the GNU Public License (GPL). As
> the message states, these modules are:
>
> postproc - video postprocessing
> libx264 - library for handling H.264/MPEG-4 AVC format video
> libx265 - library for handling H.265/HEVC format video
> libxvid - library for handling Xvid MPEG-4 Part 2 video
>
> The message about ffmpeg next tells you that if you want to include libraries
> that are not considered freely distributable for the purposes of the GPL (I
> think that this is currently only the Fraunhofer AAC code:
> https://trac.ffmpeg.org/wiki/Encode/AAC), then you should rebuild the ffmpeg
> port with the +nonfree option, which I think you could do as follows:
>
> sudo port deactivate ffmpeg && sudo port install ffmpeg +nonfree
>
> Finally, the message about ffmpeg tells you that if you don’t want the GPL
> libraries mentioned above, you should rebuild the ffmpeg port without the
> +gpl2 option (which appears to the be default, and which I normally prefer to
> install because my camera captures video in H.264/H.265). I think you could
> do this as follows:
>
> sudo port deactivate ffmpeg && sudo port install ffmpeg -gpl2
>
> 2. The second message you received regarding python27 tells you how to make
> python 2.7 the default version of python and/or python2, in other words, the
> version that would get run if you typed python and/or python2 (assuming that
> /opt/local/bin comes before /usr/bin in your $PATH).
>
> Unless you are using python 2.7 regularly or have a specific reason not to
> use the Apple provided version of python/python2, I am not sure if you really
> need to do either of these things (I never have, and I’ve been using macports
> for years).
>
> 3. The third message you received regarding python39 is similar to the
> message you received about python27 and tells you how to make python 3.9 the
> default version of python and/or python3. If you are working with python3,
> you may want to do this.
The above are not warnings; they're notes -- informational messages that the
designer of the port thought people might like to know. They do not indicate
that anything is wrong.
> 4. The message you received from ’sudo port upgrade outdated’ tells you that
> when the links port, which is installed on your system, was built, the
> '-Wimplicit-function-declaration’ option was supplied to the compiler and
> that the compiler found three functions that were implicitly declared. The
> warning is telling you that it is possible that links may not function
> properly in some situations because of this.
>
> [If you are familiar with C, apologies in advance for the following
> paragraph, including inaccuracies due to oversimplification]
>
> These days, well-formed C requires a description of a function (called a
> prototype) to be provided before a function is used for the first time. If a
> function is used without providing a prototype, when the
> '-Wimplicit-function-declaration’ option is supplied to the computer, the
> compiler tells you that you that there may be something wrong with your
> program. In this case, my guess is that somewhere in the links source code
> the standard C header file string.h should have been included but wasn’t
> (either due to oversight or because of a configuration error), and the
> compiler is highlighting this. This is probably something that should be
> fixed in the links source code, but could possibly be fixed by macports as
> well.
The version of clang included with Xcode 12 and later (so, on Big Sur and later
and sometime on Catalina) defaults to behavior equivalent to
-Werror=implicit-function-declaration which is why these problems are being
seen more lately. For a lot more on the implications of this, see my previous
write-up:
https://lists.macports.org/pipermail/macports-dev/2020-November/042648.html
