enable_language(CXX)

file(GENERATE
  OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/$<BOOL:$<TARGET_PROPERTY:foo,SOURCES>>somefile.cpp"
  CONTENT "static const char content[] = \"$<TARGET_PROPERTY:foo,SOURCES>\";\n"
)

add_custom_command(OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/generated.cpp"
  COMMAND ${CMAKE_COMMAND} -E copy "${CMAKE_CURRENT_SOURCE_DIR}/generated.cpp" "${CMAKE_CURRENT_BINARY_DIR}")

add_executable(foo empty.cpp "${CMAKE_CURRENT_BINARY_DIR}/generated.cpp")

add_executable(bar "${CMAKE_CURRENT_BINARY_DIR}/1somefile.cpp")