Build error with LLVM/Clang

[perfect7gentleman]

Error:

ninja: job failed: /usr/lib/ccache/bin/clang++ -DKCOREADDONS_LIB -DLIBINPUT_HAS_TOTEM -DQT_CONCURRENT_LIB -DQT_CORE_LIB -DQT_DBUS_LIB -DQT_DISABLE_DEPRECATED_BEFORE=0 -DQT_GUI_LIB -DQT_NETWORK_LIB -DQT_NO_DEBUG -DQT_NO_URL_CAST_FROM_STRING -DQT_QMLMODELS_LIB -DQT_QML_LIB -DQT_QUICK_LIB -DQT_SCRIPT_LIB -DQT_SENSORS_LIB -DQT_USE_QSTRINGBUILDER -DQT_WIDGETS_LIB -DQT_X11EXTRAS_LIB -DQT_XML_LIB -D_GNU_SOURCE -D_LARGEFILE64_SOURCE -Dkwin_EXPORTS -I. -I/tmp/portage/kde-plasma/kwin-5.18.91/work/kwin-lowlatency-5.18.91 -Ikwin_autogen/include -I/tmp/portage/kde-plasma/kwin-5.18.91/work/kwin-lowlatency-5.18.91/platformsupport -I/tmp/portage/kde-plasma/kwin-5.18.91/work/kwin-lowlatency-5.18.91/tabbox -I/tmp/portage/kde-plasma/kwin-5.18.91/work/kwin-lowlatency-5.18.91/effects -I/tmp/portage/kde-plasma/kwin-5.18.91/work/kwin-lowlatency-5.18.91/libkwineffects -Ilibkwineffects -Ieffects -I/usr/include/qt5/QtGui/5.15.0 -I/usr/include/qt5/QtGui/5.15.0/QtGui -I/usr/include/qt5/QtCore/5.15.0 -I/usr/include/qt5/QtCore/5.15.0/QtCore -isystem /usr/include/qt5 -isystem /usr/include/qt5/QtDBus -isystem /usr/include/qt5/QtCore -isystem /usr/lib64/qt5/mkspecs/linux-clang -isystem /usr/include/qt5/QtWidgets -isystem /usr/include/qt5/QtGui -isystem /usr/include/qt5/QtQuick -isystem /usr/include/qt5/QtQmlModels -isystem /usr/include/qt5/QtQml -isystem /usr/include/qt5/QtNetwork -isystem /usr/include/KF5/KConfigCore -isystem /usr/include/KF5 -isystem /usr/include/KF5/KCoreAddons -isystem /usr/include/KF5/KWindowSystem -isystem /usr/include/KF5/KDeclarative -isystem /usr/include/KF5/KPackage -isystem /usr/include/qt5/QtConcurrent -isystem /usr/include/qt5/QtScript -isystem /usr/include/qt5/QtSensors -isystem /usr/include/KF5/KConfigWidgets -isystem /usr/include/KF5/KCodecs -isystem /usr/include/KF5/KWidgetsAddons -isystem /usr/include/KF5/KConfigGui -isystem /usr/include/qt5/QtXml -isystem /usr/include/KF5/KAuth -isystem /usr/include/KF5/KGlobalAccel -isystem /usr/include/qt5/QtX11Extras -isystem /usr/include/KF5/KI18n -isystem /usr/include/KF5/KNotifications -isystem /usr/include/KF5/Plasma -isystem /usr/include/KF5/KService -isystem /usr/include/KDecoration2 -isystem /usr/include/KScreenLocker -isystem /usr/include/KF5/KActivities -isystem /usr/include/KF5/KWayland/Client  -DQT_NO_DEBUG -march=native -mtune=native -O3 -pipe -flto=thin -fomit-frame-pointer -fno-plt -fno-stack-protector -fno-unwind-tables -stdlib=libc++ -fno-operator-names -fno-exceptions -Wno-gnu-zero-variadic-macro-arguments -Wall -Wextra -Wcast-align -Wchar-subscripts -Wformat-security -Wno-long-long -Wpointer-arith -Wundef -Wnon-virtual-dtor -Woverloaded-virtual -Werror=return-type -Wvla -Wdate-time -fdiagnostics-color=always -fPIC -fvisibility=hidden -fvisibility-inlines-hidden   -fPIC -std=gnu++14 -MD -MT CMakeFiles/kwin.dir/colorcorrection/clockskewnotifierengine_linux.cpp.o -MF CMakeFiles/kwin.dir/colorcorrection/clockskewnotifierengine_linux.cpp.o.d -o CMakeFiles/kwin.dir/colorcorrection/clockskewnotifierengine_linux.cpp.o -c /tmp/portage/kde-plasma/kwin-5.18.91/work/kwin-lowlatency-5.18.91/colorcorrection/clockskewnotifierengine_linux.cpp
/tmp/portage/kde-plasma/kwin-5.18.91/work/kwin-lowlatency-5.18.91/colorcorrection/clockskewnotifierengine_linux.cpp:38:77: error: use of undeclared identifier 'errno'
        qWarning("Couldn't create clock skew notifier engine: %s", strerror(errno));
                                                                            ^
/tmp/portage/kde-plasma/kwin-5.18.91/work/kwin-lowlatency-5.18.91/colorcorrection/clockskewnotifierengine_linux.cpp:45:77: error: use of undeclared identifier 'errno'
        qWarning("Couldn't create clock skew notifier engine: %s", strerror(errno));
                                                                            ^
2 errors generated.

Solution: add

#include <cerrno>

to kwin-lowlatency-5.18.91/colorcorrection/clockskewnotifierengine_linux.cpp

[tildearrow]

Fixed. Thank you.