Hi Grzegorz
It sounds like your installation of the GNU toolchain might be incompatible with the project. What version of gcc-arm-embedded are you using?
Section 6.2.1: “Using Coocox IDE”, mentions GCC 4.8. I believe this project is typically used with GCC 5.4.
Note that we now primarily support the System Workbench for STM32 IDE. The CoIDE/Coocox is only supported as legacy project. The examples for System Workbench should work with the latest version of the IDE.