Compile fix for Qt 5.12.9

[atismer]

The compilation of covise on tumbleweed runs in compile errors with qt. The installed version is 5.12.9.

One issue is that the macro QT_VERSION is not defined in MEMessageHandler.h. The resulting error message is:

[ 15%] Building CXX object src/sys/mapeditor/CMakeFiles/mapeditor.dir/covise/moc_MEMessageHandler.cpp.o
/home/ati/sandbox/addLib/covise/chalinochromisopt/build.covise/src/sys/mapeditor/covise/moc_MEMessageHandler.cpp: In static member function ‘static void MEMessageHandler::qt_static_metacall(QObject*, QMetaObject::Call, int, void**)’:
/home/ati/sandbox/addLib/covise/chalinochromisopt/build.covise/src/sys/mapeditor/covise/moc_MEMessageHandler.cpp:78:54: error: expected type-specifier before ‘QSocketDescriptor’
   78 |         case 0: _t->dataReceived((*reinterpret_cast< QSocketDescriptor(*)>(_a[1])),(*reinterpret_cast< QSocketNotifier::Type(*)>(_a[2]))); break;
      |                                                      ^~~~~~~~~~~~~~~~~
/home/ati/sandbox/addLib/covise/chalinochromisopt/build.covise/src/sys/mapeditor/covise/moc_MEMessageHandler.cpp:78:54: error: expected ‘>’ before ‘QSocketDescriptor’
/home/ati/sandbox/addLib/covise/chalinochromisopt/build.covise/src/sys/mapeditor/covise/moc_MEMessageHandler.cpp:78:54: error: expected ‘(’ before ‘QSocketDescriptor’
   78 |         case 0: _t->dataReceived((*reinterpret_cast< QSocketDescriptor(*)>(_a[1])),(*reinterpret_cast< QSocketNotifier::Type(*)>(_a[2]))); break;
      |                                                      ^~~~~~~~~~~~~~~~~
      |                                                      (
/home/ati/sandbox/addLib/covise/chalinochromisopt/build.covise/src/sys/mapeditor/covise/moc_MEMessageHandler.cpp:78:73: error: expected primary-expression before ‘)’ token
   78 |         case 0: _t->dataReceived((*reinterpret_cast< QSocketDescriptor(*)>(_a[1])),(*reinterpret_cast< QSocketNotifier::Type(*)>(_a[2]))); break;
      |                                                                         ^
/home/ati/sandbox/addLib/covise/chalinochromisopt/build.covise/src/sys/mapeditor/covise/moc_MEMessageHandler.cpp:78:54: error: ‘QSocketDescriptor’ was not declared in this scope
   78 |         case 0: _t->dataReceived((*reinterpret_cast< QSocketDescriptor(*)>(_a[1])),(*reinterpret_cast< QSocketNotifier::Type(*)>(_a[2]))); break;
      |                                                      ^~~~~~~~~~~~~~~~~
make[2]: *** [src/sys/mapeditor/CMakeFiles/mapeditor.dir/build.make:2397: src/sys/mapeditor/CMakeFiles/mapeditor.dir/covise/moc_MEMessageHandler.cpp.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:12349: src/sys/mapeditor/CMakeFiles/mapeditor.dir/all] Error 2

In my opinion the macro

https://github.com/hlrs-vis/covise/blob/9ae162f51be69826b8f3a6ffeee4cda48dcd9f5e/src/sys/mapeditor/covise/MEMessageHandler.h#L52-L56

can not be correctly evaluated, due to the missing definition. A possible fix is to add

#include <QtGlobal>

to the header and to insert an include_directories() statement

find_package(Qt5Core)
INCLUDE_DIRECTORIES("${Qt5Core_INCLUDE_DIRS}")

in CMakeLists.txt. I am not sure, if this is the cleanest solution to include qt headers, but it solves the issue.

A second error occurs when compiling the file moc_MENode.cpp:

[ 31%] Generating nodes/moc_MENode.cpp
/home/ati/sandbox/addLib/covise/src/sys/mapeditor/nodes/MENode.h:57: Error: Undefined interface
make[2]: *** [src/sys/mapeditor/CMakeFiles/mapeditor.dir/build.make:306: src/sys/mapeditor/nodes/moc_MENode.cpp] Error 1

I think, the moc compiler does not know the interface QGraphicsItem

https://github.com/hlrs-vis/covise/blob/9ae162f51be69826b8f3a6ffeee4cda48dcd9f5e/src/sys/mapeditor/nodes/MENode.h#L57

and again the QT_VERSION macro. The missing interface definition can be fixed by adding

find_package(QtWidgets)
INCLUDE_DIRECTORIES("${Qt5Widgets_INCLUDE_DIRS}")

to CMakeLists.txt; the missing macro is fixed as mentioned above.