[dmd-internals] 3rd Biweekly Sprint Planning

[Iain Buclaw via dmd-internals]

On 11 August 2015 at 13:05, Martin Nowak via dmd-internals <
dmd-internals at puremagic.com> wrote:

> On 08/10/2015 07:10 PM, Iain Buclaw wrote:
> > - Do we need to keep ddmd working with 2.068?
> >
> > For the time being, yes, and for as long as possible.
>
> Sticking to an old version of the compiler defeats a major reason to
> switch to self-hosting. By using D ourselves for a big project we'll
> resolve particular issues that'll come up. But if we cannot profit from
> solving those, this will have little impact.
>
>
IMO, it only enforces that we don't immediately jump onto using new
features introduced post-2.068 within the compiler so quickly.



> So what is the major reason we need backwards compatibility for more
> than 1 version?
> After all you can always do the following.
>
> download2068
> foreach (ver; 2.069 .. 2.085)
> {
>     git checkout ver
>     buildWithPreviousVer
> }
>
>
Because I operate around GCC releases, rather than DMD.  In the 6-8 months
that a GCC development cycle and release is done, there could be many DMD
releases during that time.  If (the nonexistent) GDC-6.2 built on 2.068
cannot build GDC-7.1 (2.072) or current GDC-8.0 development snapshot
(2.075), then I have a serious problem with upstream development.



> It seems to me the key problem is to guarantee that the above works,
> which is what I meant with testing compatibility.
> The minimum IMO would be the classical self-compiling check, and of
> course a rigorous test suite.
>
> buildWithPreviousVer
> test
> buildWithCurrentVer
> test
> buildWithCurrentVer <- binary must be equal to buildWithCurrentVer above
> test
>
>
This cycle is what's done with GCC build process, if you change a few words
around.

buildWithHostCompiler
bootstrap
buildWithBuildCompiler
bootstrap
buildWithBuildCompiler
Compare md5sum of second and third stage *.o files


Regards
Iain
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