How to make invariant switchable

[Christian Kamm]

Christian Kamm Wrote:
> LDC has the -enable-* and -disable-* command line options for asserts, array bounds 
> checking, invariants and contracts to allow fine grained control over what is emitted and 
> what isn't.

Ah, Jarrett had already pointed that out. Anyway, what I meant to say was that adding 
these switches was pretty easy: as far as I remember the frontend already has individual 
options for switching the debugging aids on and off individually. So if you want this in DMD, 
make an enhancement request and append a patch. 

Unless Walter has fundamental reservations, getting it into the reference compiler (preferably
using the same flags LDC uses) would be nice.