ADD_CUSTOM_COMMAND(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/generated.h 
  COMMAND 
  ${CMAKE_COMMAND} ARGS -E
  copy ${CMAKE_CURRENT_SOURCE_DIR}/generated.h.in 
  ${CMAKE_CURRENT_BINARY_DIR}/generated.h 
)

INCLUDE_DIRECTORIES( ${CMAKE_CURRENT_BINARY_DIR})
ADD_LIBRARY(GeneratedHeader main.cpp)