backporting features to D1

[Christian Kamm]

Bill Baxter wrote:
> Porting proven, non-breaking D2.0 features to D1.0 would *not* mutate
> D1.0 into D2.0.  Const stuff would never be ported to D1.0, for
> instance because there's really no way to do it without breaking
> existing D1 code.  And since we're talking about porting proven,
> backwards-compatible features, it still means D1.0 is significantly
> more stable than D2.

I agree and would like to see the choice for not moving proven,
backwards-compatible features from the D2-playground into D1-stable
reconsidered. The big, conceptual changes like const/invariant, pure,
shared, closures, ... could not be moved to D1 without breaking existing
code, but a lot of small things could.

There should be much less complaints about getting new features every month
if these features are fully backwards-compatibly and have been tested in D2
for a while. This is particularly true for things like the partial IFTI
improvements that could be considered bugs in D1.

I think some fixes to D1 bugs will prove to be much more troublesome. We
recently applied the patch to 313/314 in LDC and that *did* break some
existing code (by exposing bugs, but still...).