QtCreator complains on opening new CMakeLists.txt project that
No CMAKE_CXX_COMPILER could be found.
Tell CMake where to find the compiler by setting either the environment
variable "CXX" or the CMake cache entry CMAKE_CXX_COMPILER to the full path
to the compiler, or to the compiler name if it is in the PATH.
The full error log starts
Running "/usr/bin/cmake /home/adas/cs40/examples '-GCodeBlocks - Unix Makefiles' -DCMAKE_CXX_COMPILER:STRING= -DQT_QMAKE_EXECUTABLE:STRING=/usr/lib/x86_64-linux-gnu/qt5/bin/qmake" in /tmp/qtc-cmake-YX2DyA.
-- The C compiler identification is GNU 5.4.0
-- The CXX compiler identification is unknown
...
Indeed the CMAKE_CXX_COMPILER string is empty
- Open qtcreator
- On the top menu, go to Tools->Options
- Select
Build & Runicon on left side See the buildrun.png image above - Select
Kitson top tab - Select
Desktop (default) - Select a legit compiler from the compiler menu, e.g., Clang x86 64bit
- If no options show up in the drop down, you may need to select manage and manually add /usr/bing/clang++ See compiler.png above
- Select Apply


Glad you found this five year old note helpful. I don't know the cause of the problem. That's perhaps a Qt question.