Compilation failure with ffmpeg 5.0

[scpeters]

Environment

• OS Version: macOS 10.15
• Source or binary build? source build all major versions 1-5

Description

ffmpeg 5.0 has just been merged in Homebrew/homebrew-core#94423

• Expected behavior: ignition-common compiles with ffmpeg
• Actual behavior: it fails to compile

Steps to reproduce

1. brew install ignition-common5
2. observer build failure

Output

cd /tmp/ignition-common5-20220203-58814-14kxgm5/events/src && /usr/local/Cellar/cmake/3.22.2/bin/cmake -E cmake_link_script CMakeFiles/ignition-common5-events.dir/link.txt --verbose=1
/tmp/ignition-common5-20220203-58814-14kxgm5/av/src/VideoEncoder.cc:132:10: error: cannot initialize return object of type 'AVCodec *' with an rvalue of type 'const AVCodec *'
  return avcodec_find_encoder(_codecId);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Homebrew/Library/Homebrew/shims/mac/super/clang++  -stdlib=libc++ -O3 -DNDEBUG -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk -dynamiclib -Wl,-headerpad_max_install_names  -Wl,-undefined -Wl,dynamic_lookup -compatibility_version 5.0.0 -current_version 5.0.0 -o "../../lib/libignition-common5-events.5.0.0~pre1.dylib" -install_name @rpath/libignition-common5-events.5.dylib CMakeFiles/ignition-common5-events.dir/Event.cc.o CMakeFiles/ignition-common5-events.dir/KeyEvent.cc.o CMakeFiles/ignition-common5-events.dir/MouseEvent.cc.o  -Wl,-rpath,/tmp/ignition-common5-20220203-58814-14kxgm5/lib "../../lib/libignition-common5.5.0.0~pre1.dylib" "/usr/local/lib/libignition-math7.7.0.0~pre1.dylib" /usr/local/lib/libignition-utils1.1.2.0.dylib -lpthread 
/tmp/ignition-common5-20220203-58814-14kxgm5/av/src/VideoEncoder.cc:370:21: error: cannot initialize a variable of type 'AVOutputFormat *' with an rvalue of type 'const AVOutputFormat *'
    AVOutputFormat *outputFormat = av_guess_format(nullptr,
                    ^              ~~~~~~~~~~~~~~~~~~~~~~~~
[ 66%] Building CXX object graphics/src/CMakeFiles/ignition-common5-graphics.dir/Image.cc.o
cd /tmp/ignition-common5-20220203-58814-14kxgm5/graphics/src && /usr/local/Homebrew/Library/Homebrew/shims/mac/super/clang++ -DMAC_OS_X_VERSION=1080 -DTINYXML2_MAJOR_VERSION_GE_6 -Dignition_common5_graphics_EXPORTS -I/tmp/ignition-common5-20220203-58814-14kxgm5/include -I/tmp/ignition-common5-20220203-58814-14kxgm5/graphics/include -I/tmp/ignition-common5-20220203-58814-14kxgm5/core/include -isystem /usr/local/include/ignition/utils1 -isystem /usr/local/include/ignition/math7 -isystem /usr/local/Cellar/pcre/8.45/include -isystem /usr/local/Cellar/glib/2.70.3/include -isystem /usr/local/Cellar/glib/2.70.3/include/glib-2.0 -isystem /usr/local/Cellar/glib/2.70.3/lib/glib-2.0/include -isystem /usr/local/opt/gettext/include -isystem /usr/local/Cellar/gts/0.7.6_2/include -isystem /usr/local/Cellar/tinyxml2/9.0.0/include -stdlib=libc++ -O3 -DNDEBUG -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk -fPIC -fPIC -I/usr/local/Cellar/pcre/8.45/include -I/usr/local/Cellar/glib/2.70.3/include -I/usr/local/Cellar/glib/2.70.3/include/glib-2.0 -I/usr/local/Cellar/glib/2.70.3/lib/glib-2.0/include -I/usr/local/opt/gettext/include -I/usr/local/Cellar/gts/0.7.6_2/include -I/usr/local/Cellar/tinyxml2/9.0.0/include -std=c++17 -MD -MT graphics/src/CMakeFiles/ignition-common5-graphics.dir/Image.cc.o -MF CMakeFiles/ignition-common5-graphics.dir/Image.cc.o.d -o CMakeFiles/ignition-common5-graphics.dir/Image.cc.o -c /tmp/ignition-common5-20220203-58814-14kxgm5/graphics/src/Image.cc
cd /tmp/ignition-common5-20220203-58814-14kxgm5/events/src && /usr/local/Cellar/cmake/3.22.2/bin/cmake -E cmake_symlink_library "../../lib/libignition-common5-events.5.0.0~pre1.dylib" ../../lib/libignition-common5-events.5.dylib ../../lib/libignition-common5-events.dylib
2 errors generated.
[ 66%] Built target ignition-common5-events
make[2]: *** [av/src/CMakeFiles/ignition-common5-av.dir/VideoEncoder.cc.o] Error 1

[mjcarroll]

Fixed by #325 , thanks @traversaro !