Tests/RunCMake/CommandLine/P_arbitrary_args.cmake - third_party/github.com/Kitware/CMake - Git at Google

 if(NOT ("${CMAKE_ARGV3}" STREQUAL "--" AND "${CMAKE_ARGV4}" STREQUAL "-DFOO"))
     message(FATAL_ERROR "`-DFOO` shouldn't trigger an error after `--`")
 endif()
	if(NOT ("${CMAKE_ARGV3}" STREQUAL "--" AND "${CMAKE_ARGV4}" STREQUAL "-DFOO"))
	message(FATAL_ERROR "`-DFOO` shouldn't trigger an error after `--`")
	endif()