example of precompiled header for clion

CMakeLists.txt

ADD_LIBRARY(PCH STATIC stdafx.cpp stdafx.h)
ADD_CUSTOM_COMMAND(TARGET PCH
                   PRE_BUILD
                   COMMAND ${CMAKE_CXX_COMMAND} -x c++-header ${CMAKE_CURRENT_SOURCE_DIR}/stdafx.h -o stdafx.h.pch)
SET_SOURCE_FILES_PROPERTIES(stdafx.cpp
                            PROPERTIES
                            COMPILE_FLAGS "-include stdafx.h")
//..

ADD_EXECUTABLE(ProjectFiles ${SOURCE_FILES})
TARGET_LINK_LIBRARIES(ProjectFiles PCH)