In Qt Creator 5.0, a <File System> node containing duplicates of all project files seems to be added to the Projects tree for all CMake projects.

To reproduce, simply create a new project using the Plain C++ Application template and select CMake as the build system. This produces the following Projects tree:

I've always thought the purpose of the <File System> node is to hold project components that don't belong anywhere else in the Projects tree. If that interpretation is correct, then this node should not be displayed for this project, since both the CMakeLists.txt and main.cpp files are already displayed elsewhere in the tree.

I've tested with snapshot 596 of Qt Creator 5.0 in Ubuntu 20.04.