[MacPorts] #48938: ffmpeg build failure on 10.6

[MacPorts]

#48938: ffmpeg build failure on 10.6
--------------------------------+-------------------------
  Reporter:  chilli.namesake@…  |      Owner:  devans@…
      Type:  defect             |     Status:  new
  Priority:  Normal             |  Milestone:
 Component:  ports              |    Version:  2.3.3
Resolution:                     |   Keywords:  snowleopard
      Port:  ffmpeg             |
--------------------------------+-------------------------

Comment (by devans@…):

 Replying to [comment:2 ryandesign@…]:
 > Snow Leopard is still supported to the extent that if something isn't
 working we will try to take a look at it if we can. But if the developers
 have made changes that make a software package require a newer version of
 OS X, then there's not much we can do about that. I don't know yet if
 that's the case here though or not.

 Ryan ---

 Thanks for your help in spotting these build errors.  As you know, I don't
 have a 10.6 machine available to test ffmpeg on this platform so I rely on
 help from those who do to fix this type of error.  This is particularly
 true since we no longer have a working 10.6 buildbot.

 So for this port, I have to take the position that problems that are
 specific to older platforms will not be addressed unless someone with the
 required hardware/software to reproduce the problem can post a specific
 fix/patch that does not effect the build on more recent platforms.

 Since ffmpeg 2.8 builds correctly on at least 10.8 and newer, I have to
 question what the difference is between those platforms and 10.6.  The
 most obvious difference is, of course, the compiler so I wonder if using a
 newer version of clang on 10.6 might fix these problems without the need
 for the various patches that you propose below.  Is this feasible and if
 so have you tried it?

 See my comments below on the specific failures.



 >
 > -----
 >
 > The log shows that the first error is:
 >
 > {{{
 > :info:build libavfilter/avf_showcqt.c:38:10: error: #include expects
 "FILENAME" or <FILENAME>
 > }}}
 >
 > This type of error is repeated a few times.
 >
 > Lines 36-39 of libavfilter/avf_showcqt.c are:
 >
 > {{{
 > #if CONFIG_LIBFREETYPE
 > #include <ft2build.h>
 > #include FT_FREETYPE_H
 > #endif
 > }}}
 >
 > This means that `CONFIG_LIBFREETYPE` is defined (as it should be), but
 that `FT_FREETYPE_H` (which should be defined in a file included by
 ft2build.h) is not defined. I think this happens because the compiler was
 invoked without specifying the directory where ft2build.h can be found
 (the argument `-I/opt/local/include/freetype2` is missing) though I don't
 understand why we didn't get a "file not found" error. It might be because
 this is not a normal compiler invocation, but rather an invocation of the
 preprocessor.
 >
 > This is a bug in ffmpeg (or else a bug in the gcc compiler exposed by
 ffmpeg's code, which ffmpeg should work around), reported with a proposed
 fix [https://lists.ffmpeg.org/pipermail/ffmpeg-
 devel/2015-September/178418.html here] (where it says that the clang
 compiler is not affected). This might not be a relevant error, since the
 build proceeds past it, but **we should probably apply this patch**.

  -----

 Comparing the 10.6 build log with the successful one on 10.10 (attached)
 shows that the build command for this module does, in fact, include
 -I/opt/local/include/freetype2 as one would expect.  The implication that
 the problem here is with the configuration system possibly compiler
 related.

 >
 > -----
 >
 > The next error in the log is:
 >
 > {{{
 > :info:build ffplay.c:3217:46: error: missing binary operator before
 token "("
 > }}}
 >
 > Line 3217 of ffplay.c is:
 >
 > {{{
 > #if defined(__APPLE__) && SDL_VERSION_ATLEAST(1, 2, 14)
 > }}}
 >
 > This implies that `SDL_VERSION_ATLEAST` is not defined. It should have
 been defined in SDL_version.h which is included by SDL.h which is included
 by ffplay.c. The reason is the same as above: this is another preprocessor
 invocation, and they haven't included the path where the SDL headers are
 found. (`-I/opt/local/include/SDL` is missing). The above fix should fix
 this as well.

 Again the 10.10 build log uses -I/opt/local/include/SDL in the build
 command so as you say this seems to be similar to the previous problem.
 Why isn't this term included on 10.6?
 >
 > -----
 >
 > The next error, and possibly the real problem, begins hundreds of lines
 of similar errors:
 >
 > {{{
 > :info:build In file included from /usr/lib/gcc/i686-apple-
 darwin10/4.2.1/include/xmmintrin.h:40,
 > :info:build                  from
 /System/Library/Frameworks/CoreServices.framework/Frameworks/CarbonCore.framework/Headers/MachineExceptions.h:29,
 > :info:build                  from
 /System/Library/Frameworks/CoreServices.framework/Frameworks/CarbonCore.framework/Headers/DriverServices.h:32,
 > :info:build                  from
 /System/Library/Frameworks/CoreServices.framework/Frameworks/CarbonCore.framework/Headers/CarbonCore.h:125,
 > :info:build                  from
 /System/Library/Frameworks/CoreServices.framework/Frameworks/AE.framework/Headers/AE.h:20,
 > :info:build                  from
 /System/Library/Frameworks/CoreServices.framework/Headers/CoreServices.h:21,
 > :info:build                  from /:19:
 > :info:build /usr/lib/gcc/i686-apple-
 darwin10/4.2.1/include/mmintrin.h:67: error: no previous prototype for
 ‘_mm_empty’
 > }}}
 >
 > We've had a report of that type of error with ffmpeg years ago in #36961
 but it was closed without a resolution, and since that was only seen by
 two users and was with a now years-old version of ffmpeg that might not be
 relevant anymore.
 >
 > We also had a report of that error with mesa in #46827. In both tickets,
 Jeremy suggested removing "`-Werror=missing-prototypes`" from the build
 system. **We should try this**.

 Possibly but it builds fine with clang on 10.8+.  Looks to be due to a
 10.6 gcc C library problem.

 At any rate, would appreciate it if you could try building with MacPorts
 clang and see if that works.  If not we need to explore this further and
 come up with a specific fix with a minimum of patches that works on 10.6
 without breaking the build on more recent platforms. As usual any fixes
 that appear to address errors in ffmpeg itself should be forwarded upstrem
 to the ffmpeg developers.

 Thanks again for your help on these older platforms.

-- 
Ticket URL: <https://trac.macports.org/ticket/48938#comment:7>
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