function(ValidateOptions ValidOptions ChoiceName DefaultChoice Choice RetVal)
	if(Choice)
		if(Choice MATCHES "ALL")
			set(${RetVal} ${ValidOptions} PARENT_SCOPE)
			message(STATUS "ALL ${ChoiceName} option set, configuring ${ValidOptions}.")
		else()
			foreach(x IN LISTS Choice)
				if(x IN_LIST ValidOptions)
					message(STATUS "Configuring for ${x}.")
				else()
					message(FATAL_ERROR "${x} not supported. The supported ${ChoiceName} are: ${ValidOptions}.")
				endif()
				set(${RetVal} ${Choice} PARENT_SCOPE)
			endforeach()
		endif()
	else()
		set(${RetVal} ${DefaultChoice} PARENT_SCOPE)
		message(STATUS "No -D${ChoiceName}= parameter, configuring ${DefaultChoice} by default.")
	endif()
endfunction()