-g and -fvar-tracking

[Sandra Loosemore]

Can somebody remind me why using -g doesn't also enable -fvar-tracking 
by default?  At least for -g2, which is supposed to emit debug 
information about local variables?  It seems kind of counterintuitive to 
me that specifying a -O option enables a pass to collect better debug 
information but specifying -g to request debuggable code doesn't.  :-S

-Sandra