Visual Studio Code is a free, multi-platform, open-source code editor from Microsoft.
Reformat Code: Ctrl-Shift-I (Linux)
Visual Studio Code has relatively good support for C and C++.
The refactoring capabilities are currently not that great, with the only option for C++ objects is “Rename all occurrences”.
There is no built-in CMake build support (e.g. you can open/build CMake based C/C++ projects in VS Code). However there is CMake syntax highlighting by way of the CMake plugin by twxs.