On 10 Sep 2014 22:13, "H. S. Teoh via Digitalmars-d" <digitalmars-d@puremagic.com> wrote:
>
> On Wed, Sep 10, 2014 at 10:58:00PM +0200, Andrej Mitrovic via Digitalmars-d wrote:
> > On 9/10/14, H. S. Teoh via Digitalmars-d <digitalmars-d@puremagic.com> wrote:
> > > - Decide on policy on how many previous releases the current
> > >   codebase must be buildable on (currently, it's just the previous
> > >   release, as I understand it);
> >
> > If by current you mean git-head, only git-head versions of DMD are
> > compatible with git-head versions of druntime and phobos. Meaning it's
> > normal that an e.g. 2.066 compiler will not build a Phobos commit
> > after the commit tagged v2.066 (it may work for a while, but things
> > usually break quick enough either through things like mangling changes
> > or accepts-invalid bug fixes, to name a few).
>
> If self-hosting is ever going to take off, we're gonna hafta restrict
> dmd source code to be compilable with at least the previous dmd release.
> Otherwise, we may end up with a compiler that can't be compiled unless
> you've already compiled it first.
>

For GDC (and distributions that ship GDC), that would extend to 3 or 4 versions, as gcc releases are a round about, or just over yearly.

Iain.