Usually, I'd not report any compile warnings, but in this case, emerge will output cc1plus: warning: ‘-Werror=’ argument ‘-Werror=implicit-function-declaration’ is not valid for C++ at *EVERY* call of /usr/bin/x86_64-pc-linux-gnu-g++ Example: [115/347] /usr/bin/x86_64-pc-linux-gnu-g++ -DKCOREADDONS_LIB -DKGUIADDONS_LIB -DQT_CONCURRENT_LIB -DQT_CORE_LIB -DQT_DBUS_LIB -DQT_GUI_LIB -DQT_MULTIMEDIA_LIB -DQT_NETWORK_LIB -DQT_NO_CAST_FROM_BYTEARRAY -DQT_NO_CAST_TO_ASCII -DQT_NO_DEBUG -DQT_NO_URL_CAST_FROM_STRI NG -DQT_QMLMODELS_LIB -DQT_QML_LIB -DQT_QUICKWIDGETS_LIB -DQT_QUICK_LIB -DQT_STRICT_ITERATORS -DQT_SVG_LIB -DQT_WIDGETS_LIB -DQT_XML_LIB -DRTTR_DLL -DTRANSLATION_DOMAIN=\"kdenlive\" -DUSE_JOGSHUTTLE -D_GNU_SOURCE -D_LARGEFILE64_SOURCE -Isrc -I/var/tmp/portage/kde-ap ps/kdenlive-19.08.3/work/kdenlive-19.08.3/src -Isrc/kdenliveLib_autogen/include -I. -I/var/tmp/portage/kde-apps/kdenlive-19.08.3/work/kdenlive-19.08.3/src/lib/external -I/var/tmp/portage/kde-apps/kdenlive-19.08.3/work/kdenlive-19.08.3/src/lib -I/var/tmp/portage/kde- apps/kdenlive-19.08.3/work/kdenlive-19.08.3/src/SYSTEM -Isrc/lib/external/kiss_fft -I/var/tmp/portage/kde-apps/kdenlive-19.08.3/work/kdenlive-19.08.3/src/lib/external/kiss_fft -Isrc/lib/external/media_ctrl -I/var/tmp/portage/kde-apps/kdenlive-19.08.3/work/kdenlive-1 9.08.3/src/lib/external/media_ctrl -I/usr/include/mlt -isystem /usr/include/KF5/KWidgetsAddons -isystem /usr/include/KF5 -isystem /usr/include/qt5 -isystem /usr/include/qt5/QtWidgets -isystem /usr/include/qt5/QtGui -isystem /usr/include/qt5/QtCore -isystem /usr/lib6 4/qt5/mkspecs/linux-g++ -isystem /usr/include/KF5/KArchive -isystem /usr/include/KF5/KCoreAddons -isystem /usr/include/KF5/KIOCore -isystem /usr/include/KF5/KService -isystem /usr/include/KF5/KConfigCore -isystem /usr/include/qt5/QtNetwork -isystem /usr/include/qt5/ QtConcurrent -isystem /usr/include/qt5/QtDBus -isystem /usr/include/KF5/KIOFileWidgets -isystem /usr/include/KF5/KIOWidgets -isystem /usr/include/KF5/KJobWidgets -isystem /usr/include/KF5/KCompletion -isystem /usr/include/KF5/KBookmarks -isystem /usr/include/qt5/QtX ml -isystem /usr/include/KF5/KItemViews -isystem /usr/include/KF5/KXmlGui -isystem /usr/include/KF5/KConfigWidgets -isystem /usr/include/KF5/KCodecs -isystem /usr/include/KF5/KConfigGui -isystem /usr/include/KF5/KAuth -isystem /usr/include/KF5/Solid -isystem /usr/in clude/KF5/KNotifyConfig -isystem /usr/include/KF5/KNewStuff3 -isystem /usr/include/KF5/KNewStuff3/KNS3 -isystem /usr/include/KF5/KNewStuff3/knscore -isystem /usr/include/KF5/KNewStuff3/kns3 -isystem /usr/include/KF5/KNewStuff3/KNSCore -isystem /usr/include/KF5/Attic a -isystem /usr/include/KF5/KDBusAddons -isystem /usr/include/KF5/KGuiAddons -isystem /usr/include/KF5/KNotifications -isystem /usr/include/KF5/KTextWidgets -isystem /usr/include/KF5/SonnetUi -isystem /usr/include/KF5/KI18n -isystem /usr/include/KF5/KDeclarative -is ystem /usr/include/qt5/QtQml -isystem /usr/include/KF5/KPackage -isystem /usr/include/KF5/KIconThemes -isystem /usr/include/qt5/QtSvg -isystem /usr/include/qt5/QtQuick -isystem /usr/include/qt5/QtQmlModels -isystem /usr/include/qt5/QtQuickWidgets -isystem /usr/inclu de/qt5/QtMultimedia -DQT_NO_DEBUG -DNDEBUG -O2 -pipe -fno-operator-names -fno-exceptions -Wall -Wextra -Wcast-align -Wchar-subscripts -Wformat-security -Wno-long-long -Wpointer-arith -Wundef -Wnon-virtual-dtor -Woverloaded-virtual -Werror=return-type -Wvla -Wdate-t ime -Wsuggest-override -Wlogical-op -fdiagnostics-color=always -fPIC -Wno-suggest-override -fvisibility=hidden -fvisibility-inlines-hidden -Wall -pedantic -Wextra -Wcast-qual -Wcast-align -Wfloat-equal -Wpointer-arith -Wunreachable-code -Wchar-subscripts -Wcomme nt -Wformat -Werror-implicit-function-declaration -Wmain -Wmissing-braces -Wparentheses -Wsequence-point -Wreturn-type -Wswitch -Wuninitialized -Wreorder -Wundef -Wshadow -Wwrite-strings -Wmissing-noreturn -Wsign-compare -Wsign-conversion -Wunused -Wstrict-aliasing -Wconversion -Wdisabled-optimization -Wno-undef -Wunused-parameter -Wshadow -Wno-variadic-macros -Wno-float-conversion -fPIC -std=gnu++14 -MD -MT src/CMakeFiles/kdenliveLib.dir/kdenliveLib_autogen/mocs_compilation.cpp.o -MF src/CMakeFiles/kdenliveLib.dir/kdenliveLib _autogen/mocs_compilation.cpp.o.d -o src/CMakeFiles/kdenliveLib.dir/kdenliveLib_autogen/mocs_compilation.cpp.o -c src/kdenliveLib_autogen/mocs_compilation.cpp cc1plus: warning: ‘-Werror=’ argument ‘-Werror=implicit-function-declaration’ is not valid for C++ [116/347] /usr/bin/x86_64-pc-linux-gnu-g++ -DKCOREADDONS_LIB -DKGUIADDONS_LIB -DQT_CONCURRENT_LIB -DQT_CORE_LIB -DQT_DBUS_LIB -DQT_GUI_LIB -DQT_MULTIMEDIA_LIB -DQT_NETWORK_LIB -DQT_NO_CAST_FROM_BYTEARRAY -DQT_NO_CAST_TO_ASCII -DQT_NO_DEBUG -DQT_NO_URL_CAST_FROM_STRI NG -DQT_QMLMODELS_LIB -DQT_QML_LIB -DQT_QUICKWIDGETS_LIB -DQT_QUICK_LIB -DQT_STRICT_ITERATORS -DQT_SVG_LIB -DQT_WIDGETS_LIB -DQT_XML_LIB -DRTTR_DLL -DTRANSLATION_DOMAIN=\"kdenlive\" -DUSE_JOGSHUTTLE -D_GNU_SOURCE -D_LARGEFILE64_SOURCE -Isrc -I/var/tmp/portage/kde-ap ps/kdenlive-19.08.3/work/kdenlive-19.08.3/src -Isrc/kdenliveLib_autogen/include -I. -I/var/tmp/portage/kde-apps/kdenlive-19.08.3/work/kdenlive-19.08.3/src/lib/external -I/var/tmp/portage/kde-apps/kdenlive-19.08.3/work/kdenlive-19.08.3/src/lib -I/var/tmp/portage/kde- apps/kdenlive-19.08.3/work/kdenlive-19.08.3/src/SYSTEM -Isrc/lib/external/kiss_fft -I/var/tmp/portage/kde-apps/kdenlive-19.08.3/work/kdenlive-19.08.3/src/lib/external/kiss_fft -Isrc/lib/external/media_ctrl -I/var/tmp/portage/kde-apps/kdenlive-19.08.3/work/kdenlive-1 9.08.3/src/lib/external/media_ctrl -I/usr/include/mlt -isystem /usr/include/KF5/KWidgetsAddons -isystem /usr/include/KF5 -isystem /usr/include/qt5 -isystem /usr/include/qt5/QtWidgets -isystem /usr/include/qt5/QtGui -isystem /usr/include/qt5/QtCore -isystem /usr/lib6 4/qt5/mkspecs/linux-g++ -isystem /usr/include/KF5/KArchive -isystem /usr/include/KF5/KCoreAddons -isystem /usr/include/KF5/KIOCore -isystem /usr/include/KF5/KService -isystem /usr/include/KF5/KConfigCore -isystem /usr/include/qt5/QtNetwork -isystem /usr/include/qt5/ QtConcurrent -isystem /usr/include/qt5/QtDBus -isystem /usr/include/KF5/KIOFileWidgets -isystem /usr/include/KF5/KIOWidgets -isystem /usr/include/KF5/KJobWidgets -isystem /usr/include/KF5/KCompletion -isystem /usr/include/KF5/KBookmarks -isystem /usr/include/qt5/QtX ml -isystem /usr/include/KF5/KItemViews -isystem /usr/include/KF5/KXmlGui -isystem /usr/include/KF5/KConfigWidgets -isystem /usr/include/KF5/KCodecs -isystem /usr/include/KF5/KConfigGui -isystem /usr/include/KF5/KAuth -isystem /usr/include/KF5/Solid -isystem /usr/in clude/KF5/KNotifyConfig -isystem /usr/include/KF5/KNewStuff3 -isystem /usr/include/KF5/KNewStuff3/KNS3 -isystem /usr/include/KF5/KNewStuff3/knscore -isystem /usr/include/KF5/KNewStuff3/kns3 -isystem /usr/include/KF5/KNewStuff3/KNSCore -isystem /usr/include/KF5/Attic a -isystem /usr/include/KF5/KDBusAddons -isystem /usr/include/KF5/KGuiAddons -isystem /usr/include/KF5/KNotifications -isystem /usr/include/KF5/KTextWidgets -isystem /usr/include/KF5/SonnetUi -isystem /usr/include/KF5/KI18n -isystem /usr/include/KF5/KDeclarative -is ystem /usr/include/qt5/QtQml -isystem /usr/include/KF5/KPackage -isystem /usr/include/KF5/KIconThemes -isystem /usr/include/qt5/QtSvg -isystem /usr/include/qt5/QtQuick -isystem /usr/include/qt5/QtQmlModels -isystem /usr/include/qt5/QtQuickWidgets -isystem /usr/inclu de/qt5/QtMultimedia -DQT_NO_DEBUG -DNDEBUG -O2 -pipe -fno-operator-names -fno-exceptions -Wall -Wextra -Wcast-align -Wchar-subscripts -Wformat-security -Wno-long-long -Wpointer-arith -Wundef -Wnon-virtual-dtor -Woverloaded-virtual -Werror=return-type -Wvla -Wdate-t ime -Wsuggest-override -Wlogical-op -fdiagnostics-color=always -fPIC -Wno-suggest-override -fvisibility=hidden -fvisibility-inlines-hidden -Wall -pedantic -Wextra -Wcast-qual -Wcast-align -Wfloat-equal -Wpointer-arith -Wunreachable-code -Wchar-subscripts -Wcomme nt -Wformat -Werror-implicit-function-declaration -Wmain -Wmissing-braces -Wparentheses -Wsequence-point -Wreturn-type -Wswitch -Wuninitialized -Wreorder -Wundef -Wshadow -Wwrite-strings -Wmissing-noreturn -Wsign-compare -Wsign-conversion -Wunused -Wstrict-aliasing -Wconversion -Wdisabled-optimization -Wno-undef -Wunused-parameter -Wshadow -Wno-variadic-macros -Wno-float-conversion -fPIC -std=gnu++14 -MD -MT src/CMakeFiles/kdenliveLib.dir/assets/keyframes/model/rotoscoping/rotohelper.cpp.o -MF src/CMakeFiles/kdenliveLib.dir/as sets/keyframes/model/rotoscoping/rotohelper.cpp.o.d -o src/CMakeFiles/kdenliveLib.dir/assets/keyframes/model/rotoscoping/rotohelper.cpp.o -c /var/tmp/portage/kde-apps/kdenlive-19.08.3/work/kdenlive-19.08.3/src/assets/keyframes/model/rotoscoping/rotohelper.cpp cc1plus: warning: ‘-Werror=’ argument ‘-Werror=implicit-function-declaration’ is not valid for C++ This seems to be new with GCC 9.2 Reproducible: Always
Is there an upstream ticket?
Short answer: No --- According to https://kdenlive.org/en/bug-reports/ their bugtracker is located here (note the search filter): https://bugs.kde.org/buglist.cgi?bug_status=__open__&list_id=1248416&order=Importance&product=kdenlive After searching closed tickets as well I found related (but not relevant) bug from 2019-11-05 against kdenlive 19.11.70 https://bugs.kde.org/show_bug.cgi?id=413416
All good then.