CMake configuration fails with Qt 6.8.0

[petrmanek]

Hello! I recently switched to Qt 6.8 and started encountering a failure during cmake configuration, which makes it impossible to build anything.

Here is basic information about my setup:

• I am building QuickQanava from source through cmake's add_subdirectory() command. My program is later linked with the QuickQanava target.
• I am using QuickQanava 6.4.1, although I have verified that the same error also happens with version 6.5.0.
• My compiler is clang 18.1.8.
• My cmake version is 3.30.5.

Building QuickQanava for Qt6
QuickQanava building with Qt6
src/CMakeLists.qt6.txt
CMake Error at /usr/lib/cmake/Qt6Core/Qt6CoreMacros.cmake:227 (string):
  string sub-command SUBSTRING requires four arguments.
Call Stack (most recent call first):
  /usr/lib/cmake/Qt6Core/Qt6CoreMacros.cmake:184 (_qt_internal_wrap_cpp)
  /usr/lib/cmake/Qt6Core/Qt6CoreMacros.cmake:299 (qt6_wrap_cpp)
  lib/quickqanava/src/CMakeLists.qt6.txt:10 (qt_wrap_cpp)
  lib/quickqanava/src/CMakeLists.txt:95 (include)


CMake Error at /usr/lib/cmake/Qt6Core/Qt6CoreMacros.cmake:265 (message):
  qt6_wrap_cpp: Unknown file extension: ".".
Call Stack (most recent call first):
  /usr/lib/cmake/Qt6Core/Qt6CoreMacros.cmake:184 (_qt_internal_wrap_cpp)
  /usr/lib/cmake/Qt6Core/Qt6CoreMacros.cmake:299 (qt6_wrap_cpp)
  lib/quickqanava/src/CMakeLists.qt6.txt:10 (qt_wrap_cpp)
  lib/quickqanava/src/CMakeLists.txt:95 (include)


-- Configuring incomplete, errors occurred!

It seems that source of the problem is invalid syntax on this line, which means that this issue could be related to #229.

Please advise.

[petrmanek]

Looking at open PR's, it seems that #253 may be able to address this issue.

[petrmanek]

@cneben Can we please get some response from maintainers? This issue has been open for several months at this point, and is (in my humble opinion) easily remedied.