How to disable a src.conf on command-line

[Jeremie Le Hen]

Hi list !

I wonder what's the trick to enable (resp. disable) a feature that has
been switched with a WITH_FOO/WITHOUT_FOO knob in src.conf(5) or
make.conf(5).

I can't find one myself because bsd.own.mk only check if the knob is
defined, it doesn't care of its value.  Furthermore it is an error to
define both WITH_FOO and WITHOUT_FOO.

My thought on this is WITH_FOO/WITHOUT_FOO knob are to be used for
software inclusion/exclusion in the base system, but not to
enable/disable compilation flags, since you can't disable it without
editing src.conf(5).

(My concern is about activation of stack-smashing protection compiler
options.  I'd like the user to be able to use -DWITHOUT_SSP to
compile something, even if he has WITH_SSP=YES in src.conf(5).
Should I turn the name of this options into ENABLE_SSP and pull it
out the bsd.own.mk magic ?)

Thank you.i
Regards,
-- 
Jeremie Le Hen
< jeremie at le-hen dot org >< ttz at chchile dot org >