Building on Linux 5.15.0-67-generic #74-Ubuntu SMP with QT version 5.15.3 encountered this error when building from source:

/usr/bin/ld: CMakeFiles/hedgewars.dir/util/FileEngine.cpp.o:(.data.rel.ro._ZTV10FileEngine[_ZTV10FileEngine]+0x20): undefined reference to `QAbstractFileEngine::open(QFlags, std::optional >)'
/usr/bin/ld: CMakeFiles/hedgewars.dir/util/FileEngine.cpp.o:(.data.rel.ro._ZTV10FileEngine[_ZTV10FileEngine]+0x88): undefined reference to `QAbstractFileEngine::mkdir(QString const&, bool, std::optional >) const'
collect2: error: ld returned 1 exit status
make[2]: *** [QTfrontend/CMakeFiles/hedgewars.dir/build.make:3745: bin/hedgewars] Error 1
make[1]: *** [CMakeFiles/Makefile2:2649: QTfrontend/CMakeFiles/hedgewars.dir/all] Error 2
make: *** [Makefile:166: all] Error 2