@Kanni1303

I guess you might have run into the same problem:

/home/myhomeismycastle/raspi/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64/bin/arm-linux-gnueabihf-g++ -c -include .pch/Qt5Core -march=armv8-a -mtune=cortex-a53 -mfpu=crypto-neon-fp-armv8 -mfloat-abi=hard --sysroot=/home/myhomeismycastle/raspi/sysroot -O3 -std=c++11 -fvisibility=hidden -fvisibility-inlines-hidden -Wall -W -Wvla -Wno-missing-field-initializers -D_REENTRANT -fPIC -DQT_NO_USING_NAMESPACE -DQT_NO_FOREACH -DQT_NO_NARROWING_CONVERSIONS_IN_CONNECT -DQT_BUILD_CORE_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 -D_LARGEFILE64_SOURCE -D_LARGEFILE_SOURCE -DQT_NO_DEBUG -DPCRE2_CODE_UNIT_WIDTH=16 -I. -Iglobal -I../3rdparty/harfbuzz/src -I../3rdparty/md5 -I../3rdparty/md4 -I../3rdparty/sha3 -I../3rdparty/forkfd -I../3rdparty/tinycbor/src -I../../include -I../../include/QtCore -I../../include/QtCore/5.12.0 -I../../include/QtCore/5.12.0/QtCore -I.moc -I.tracegen -I../3rdparty/pcre2/src -I/home/myhomeismycastle/raspi/sysroot/usr/include/glib-2.0 -I/home/myhomeismycastle/raspi/sysroot/usr/lib/arm-linux-gnueabihf/glib-2.0/include -I../../mkspecs/devices/linux-rasp-pi3-g++ -o .obj/qendian.o global/qendian.cpp In file included from global/qendian.cpp:41:0: global/qendian.h:165:61: error: redeclaration ‘constexpr T qbswap(T) [with T = qfloat16]’ differs in ‘constexpr’ template <> inline qfloat16 qbswap<qfloat16>(qfloat16 source) ^ global/qendian.h:96:42: error: from previous declaration ‘constexpr T qbswap(T) [with T = qfloat16]’ template <typename T> Q_DECL_CONSTEXPR T qbswap(T source); ^ global/qendian.h:170:52: error: redeclaration ‘constexpr T qbswap(T) [with T = float]’ differs in ‘constexpr’ template <> inline float qbswap<float>(float source) ^ global/qendian.h:96:42: error: from previous declaration ‘constexpr T qbswap(T) [with T = float]’ template <typename T> Q_DECL_CONSTEXPR T qbswap(T source); ^ global/qendian.h:175:55: error: redeclaration ‘constexpr T qbswap(T) [with T = double]’ differs in ‘constexpr’ template <> inline double qbswap<double>(double source) ^ global/qendian.h:96:42: error: from previous declaration ‘constexpr T qbswap(T) [with T = double]’ template <typename T> Q_DECL_CONSTEXPR T qbswap(T source); ^ Makefile:11849: recipe for target '.obj/qendian.o' failed make[2]: *** [.obj/qendian.o] Error 1 make[2]: Leaving directory '/home/myhomeismycastle/raspi/qt-everywhere-src-5.12.0/qtbase/src/corelib' Makefile:224: recipe for target 'sub-corelib-make_first' failed make[1]: *** [sub-corelib-make_first] Error 2 make[1]: Leaving directory '/home/myhomeismycastle/raspi/qt-everywhere-src-5.12.0/qtbase/src' Makefile:48: recipe for target 'sub-src-make_first' failed make: *** [sub-src-make_first] Error 2

I have tried to cross-compile the complete source of Qt 5.12.0 from archives, which did you cross-compile?

I saw that you actually skip wayland, which is my reason for trying Qt 5.12.0. I still have issues using openGL on raspberry pi3 and I thought that I can fix only with latest Qt 5.12. Did you get as far yet?

A quick and final update:

https://bugreports.qt.io/browse/QTBUG-72641
The topic was reopened - in no small part due to @Kalileo I believe ;-) - and the error seems to be found and fixed.

The fixed version seems to be the upcoming 5.12.1 and onwards.

Thanks everyone for the interest and help in the issue.

@raven-worx
Thanks a lot. Now, I got a perspective on how I can proceed further. I will try the solution with the QWebSocket and see how that goes.
Cheers!

@Bastien

I build with MinGW on Qt Creator. And when I use DLL, I've the error.

I didn't ask you that. I know that. That's why I asked you:

And when you build it in Visual Studio you are using the MinGW compiler, not the MSVC one, just like you show you are using from Qt Creator, right?

So I asked you what compiler you are using from Visual Studio, not Qt Creator.

Having to make a guess and assuming you use MinGW from Qt Creator but MSVC from VS, I imagine that is precisely the answer to your:

This code works fine in Visual Studio but not in QtCreator... Why ?