Note on philosophy of the make system

Make options can be divided into two classes.

• Configuration-time options Things which have an effect on the resulting executable. E.g. optimisation or debugging options.
• Make-time options Things which don't effect the final executable. E.g. warning-flags, flags to make in parallel.

Whenever an option is added to the make system care should be taken to preserve this distinction. It should be possible to go to the config-data directory of a configuration and examine the files there to determine how an executable was built. It should not be necessary to know the command-line used to build it.