build error for src/client/qwaylandwindow_p.h

...
g++ -c -pipe -g -Og -std=c++1z -fvisibility=hidden -fvisibility-inlines-hidden -fno-exceptions -Wall -W -Wvla -Wdate-time -D_REENTRANT -fPIC -DQT_WAYLAND_COMPOSITOR_QUICK -DQT_NO_NARROWING_CONVERSIONS_IN_CONNECT -DQT_BUILD_WAYLANDCOMPOSITOR_LIB -DQT_BUILDING_QT -DQT_NO_CAST_TO_ASCII -DQT_ASCII_CAST_WARNINGS -DQT_MOC_COMPAT -DQT_USE_QSTRINGBUILDER -DQT_DEPRECATED_WARNINGS -DQT_DISABLE_DEPRECATED_BEFORE=0x050000 -DQT_NO_EXCEPTIONS -D_LARGEFILE64_SOURCE -D_LARGEFILE_SOURCE -DQT_QUICK_LIB -DQT_GUI_LIB -DQT_QML_LIB -DQT_NETWORK_LIB -DQT_CORE_LIB -DQT_NAMESPACE=TestNamespace -Wall -Wextra -Werror -Woverloaded-virtual -Wshadow -Wundef -Wfloat-equal -Wnon-virtual-dtor -Wpointer-arith -Wformat-security -Wno-long-long -Wno-variadic-macros -pedantic-errors -Wchar-subscripts -Wold-style-cast -Wcast-align -Wdouble-promotion -Wzero-as-null-pointer-constant -I/home/qt/work/qt/qtwayland/src/compositor -I. -I/home/qt/work/qt/qtwayland/src/shared -I/home/qt/work/qt/qtwayland/src/compositor/global -I/home/qt/work/qt/qtwayland/src/compositor/wayland_wrapper -I/home/qt/work/qt/qtwayland/src/compositor/compositor_api -I/home/qt/work/qt/qtwayland/src/compositor/extensions -I../../include -I../../include/QtWaylandCompositor -I../../include/QtWaylandCompositor/5.11.0 -I../../include/QtWaylandCompositor/5.11.0/QtWaylandCompositor -I/home/qt/work/install/include/QtQuick/5.11.0 -I/home/qt/work/install/include/QtQuick/5.11.0/QtQuick -I/home/qt/work/install/include/QtGui/5.11.0 -I/home/qt/work/install/include/QtGui/5.11.0/QtGui -I/home/qt/work/install/include/QtQml/5.11.0 -I/home/qt/work/install/include/QtQml/5.11.0/QtQml -I/home/qt/work/install/include/QtCore/5.11.0 -I/home/qt/work/install/include/QtCore/5.11.0/QtCore -I/home/qt/work/install/include -I/home/qt/work/install/include/QtQuick -I/home/qt/work/install/include/QtGui -I/home/qt/work/install/include/QtQml -I/home/qt/work/install/include/QtNetwork -I/home/qt/work/install/include/QtCore -I.moc -isystem /usr/include/libdrm -I/home/qt/work/install/mkspecs/linux-g++ -DQT_NO_CAST_TO_ASCII=1 -DQT_NO_CAST_FROM_ASCII=1 -UQT_RESTRICTED_CAST_FROM_ASCII -DQT_STRICT_ITERATORS -DQT_NO_URL_CAST_FROM_STRING=1 -DQT_NO_CAST_FROM_BYTEARRAY=1 -DQT_NO_KEYWORDS=1 -DQT_USE_QSTRINGBUILDER -DQT_USE_FAST_OPERATOR_PLUS -Dsignals=int -Dslots=int -Demit=public: -Dforeach=public: -Dforever=public: -xc++ /home/qt/work/qt/qtwayland/src/compositor/compositor_api/qwaylandseat.h -o .obj/header_qwaylandseat.o
In file included from /home/qt/work/qt/qtwayland/src/client/qwaylandshmbackingstore.cpp:40:0:
/home/qt/work/qt/qtwayland/src/client/qwaylandwindow_p.h:146:21: error: invalid covariant return type for ‘virtual TestNamespace::QtWaylandClient::QWaylandScreen* TestNamespace::QtWaylandClient::QWaylandWindow::screen() const’
     QWaylandScreen *screen() const { return mScreen; }
                     ^
In file included from /home/qt/work/qt/qtwayland/src/client/qwaylandshmbackingstore_p.h:58:0,
                 from /home/qt/work/qt/qtwayland/src/client/qwaylandshmbackingstore.cpp:39:
/home/qt/work/install/include/QtGui/5.11.0/QtGui/qpa/qplatformwindow.h:82:22: error:   overriding ‘virtual TestNamespace::QPlatformScreen* TestNamespace::QPlatformWindow::screen() const’
     QPlatformScreen *screen() const override;
                      ^
/home/qt/work/qt/qtwayland/src/client/qwaylandshmbackingstore.cpp: In destructor ‘virtual TestNamespace::QtWaylandClient::QWaylandShmBuffer::~QWaylandShmBuffer()’:
/home/qt/work/qt/qtwayland/src/client/qwaylandshmbackingstore.cpp:128:62: warning: ‘int TestNamespace::QImage::byteCount() const’ is deprecated [-Wdeprecated-declarations]
         munmap((void *) mImage.constBits(), mImage.byteCount());
                                                              ^
In file included from /home/qt/work/install/include/QtGui/qpixmap.h:49:0,
                 from /home/qt/work/install/include/QtGui/qicon.h:46,
                 from /home/qt/work/install/include/QtGui/qwindow.h:55,
                 from /home/qt/work/install/include/QtGui/5.11.0/QtGui/qpa/qplatformbackingstore.h:56,
                 from /home/qt/work/qt/qtwayland/src/client/qwaylandshmbackingstore_p.h:56,
                 from /home/qt/work/qt/qtwayland/src/client/qwaylandshmbackingstore.cpp:39:
/home/qt/work/install/include/QtGui/qimage.h:218:23: note: declared here
     QT_DEPRECATED int byteCount() const;
                       ^
/home/qt/work/qt/qtwayland/src/client/qwaylandshmbackingstore.cpp: In member function ‘void TestNamespace::QtWaylandClient::QWaylandShmBackingStore::resize(const TestNamespace::QSize&)’:
/home/qt/work/qt/qtwayland/src/client/qwaylandshmbackingstore.cpp:290:65: warning: ‘int TestNamespace::QImage::byteCount() const’ is deprecated [-Wdeprecated-declarations]
     int oldSize = mBackBuffer ? mBackBuffer->image()->byteCount() : 0;
                                                                 ^
In file included from /home/qt/work/install/include/QtGui/qpixmap.h:49:0,
                 from /home/qt/work/install/include/QtGui/qicon.h:46,
                 from /home/qt/work/install/include/QtGui/qwindow.h:55,
                 from /home/qt/work/install/include/QtGui/5.11.0/QtGui/qpa/qplatformbackingstore.h:56,
                 from /home/qt/work/qt/qtwayland/src/client/qwaylandshmbackingstore_p.h:56,
                 from /home/qt/work/qt/qtwayland/src/client/qwaylandshmbackingstore.cpp:39:
/home/qt/work/install/include/QtGui/qimage.h:218:23: note: declared here
     QT_DEPRECATED int byteCount() const;
                       ^
/home/qt/work/qt/qtwayland/src/client/qwaylandshmbackingstore.cpp:292:72: warning: ‘int TestNamespace::QImage::byteCount() const’ is deprecated [-Wdeprecated-declarations]
     if (mBackBuffer != buffer && oldSize == buffer->image()->byteCount()) {
                                                                        ^
In file included from /home/qt/work/install/include/QtGui/qpixmap.h:49:0,
                 from /home/qt/work/install/include/QtGui/qicon.h:46,
                 from /home/qt/work/install/include/QtGui/qwindow.h:55,
                 from /home/qt/work/install/include/QtGui/5.11.0/QtGui/qpa/qplatformbackingstore.h:56,
                 from /home/qt/work/qt/qtwayland/src/client/qwaylandshmbackingstore_p.h:56,
                 from /home/qt/work/qt/qtwayland/src/client/qwaylandshmbackingstore.cpp:39:
/home/qt/work/install/include/QtGui/qimage.h:218:23: note: declared here
     QT_DEPRECATED int byteCount() const;
                       ^
/home/qt/work/qt/qtwayland/src/client/qwaylandshmbackingstore.cpp:293:103: warning: ‘int TestNamespace::QImage::byteCount() const’ is deprecated [-Wdeprecated-declarations]
         memcpy(buffer->image()->bits(), mBackBuffer->image()->constBits(), buffer->image()->byteCount());
                                                                                                       ^
In file included from /home/qt/work/install/include/QtGui/qpixmap.h:49:0,
                 from /home/qt/work/install/include/QtGui/qicon.h:46,
                 from /home/qt/work/install/include/QtGui/qwindow.h:55,
                 from /home/qt/work/install/include/QtGui/5.11.0/QtGui/qpa/qplatformbackingstore.h:56,
                 from /home/qt/work/qt/qtwayland/src/client/qwaylandshmbackingstore_p.h:56,
                 from /home/qt/work/qt/qtwayland/src/client/qwaylandshmbackingstore.cpp:39:
/home/qt/work/install/include/QtGui/qimage.h:218:23: note: declared here
     QT_DEPRECATED int byteCount() const;
                       ^
Makefile:3181: recipe for target '.obj/qwaylandshmbackingstore.o' failed
make[2]: *** [.obj/qwaylandshmbackingstore.o] Error 1
make[2]: Leaving directory '/home/qt/work/build/src/client'
Makefile:73: recipe for target 'sub-client-make_first' failed
make[1]: *** [sub-client-make_first] Error 2
make[1]: *** Waiting for unfinished jobs....