CODEWITHSUNDEEP
c++11c++17qt5backwards-compatibilityqt6
Julien
Julien

Reputation: 1

Qt 5 project won't compile in Qt 6 despite core5compat and QT_DISABLE_DEPRECATED_BEFORE

My computer has recently undergone a fresh install on Debian 12 after some mayhem in updating Ubuntu. I reinstalled Qt Creator and Qt6.6. I opened several old projects that used to work under Qt5.something (I think it was 5.15 but I have no way to verify it) on my previous installation 2 weeks ago. When trying to build them with qmake, they would not compile anymore and throw hundreds of errors, all with undefined references to core libraries including QByteArray, QDateTime, QString...

After Googleing the problem, I downloaded the Qt5 compatibility module via Qt Manager and I proceeded to add QT += core5compat to my .pro and try with or without DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x050F00 and with C++11 or C++17

This hasn't change the outcome. Am I missing something ?

Typical errors that are fired during the compilation (in this case, we're talking 1030 errors on a 500 lines code, non in the code itself) look like

:-1: error: /home/pathToProjects/ScarTest/../build/simbaLib/Desktop/Debug/libsimbaLib.a(crc8message.o): in function `CRC8Message::basecmd()':
/home/pathToProjects/simbaLib/crc8message.cpp:11: error: undefined reference to `QByteArray::QByteArray(char const*, int)'
:-1: error: /home/pathToProjects/ScarTest/../build/simbaLib/Desktop/Debug/libsimbaLib.a(crc8message.o): in function `QArrayData::sharedNull()':
/usr/include/x86_64-linux-gnu/qt5/QtCore/qarraydata.h:122: error: undefined reference to `QArrayData::shared_null'
:-1: error: /home/pathToProjects/ScarTest/../build/simbaLib/Desktop/Debug/libsimbaLib.a(crc8message.o): in function `QByteArray::detach()':
/usr/include/x86_64-linux-gnu/qt5/QtCore/qbytearray.h:501: error: undefined reference to `QByteArray::reallocData(unsigned int, QFlags<QArrayData::AllocationOption>)'
:-1: error: /home/pathToProjects/ScarTest/../build/simbaLib/Desktop/Debug/libsimbaLib.a(crc8message.o): in function `QByteRef::operator=(char)':
/usr/include/x86_64-linux-gnu/qt5/QtCore/qbytearray.h:542: error: undefined reference to `QByteArray::expand(int)'
:-1: error: /home/pathToProjects/ScarTest/../build/simbaLib/Desktop/Debug/libsimbaLib.a(crc8message.o): in function `QTypedArrayData<char>::deallocate(QArrayData*)':
/usr/include/x86_64-linux-gnu/qt5/QtCore/qarraydata.h:228: error: undefined reference to `QArrayData::deallocate(QArrayData*, unsigned long, unsigned long)'
:-1: error: /home/pathToProjects/ScarTest/../build/simbaLib/Desktop/Debug/libsimbaLib.a(qftp.o): in function `QFtpDTP::read(char*, long long)':
/home/pathToProjects/simbaLib/qftp.cpp:376: error: undefined reference to `QByteArray::remove(int, int)'

Upvotes: 0

Views: 840

Answers (1)

Jens
Jens

Reputation: 6329

While Qt6 introduced a lot of bugs and nasty API changes, I think, your main problem is the combination of Qt5 built libraries and Qt6 sources. See your bugs like

"/usr/include/x86_64-linux-gnu/qt5/QtCore/qbytearray.h:542: error:"

You need to get everything to Qt6, you can't just port part of the code and hope for binary compatibility. It seems that simbaLib is Qt5.

Upvotes: 0

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