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List:       macports-users
Subject:    Re: Notes & warning after update.
From:       Ryan Schmidt <ryandesign () macports ! org>
Date:       2021-10-27 19:31:19
Message-ID: 99DE3472-2407-4457-9AF8-D5DEEA18BB0C () macports ! org
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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


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