Phobos and older DMD versions

[Jonathan M Davis]

On Tuesday, August 06, 2013 20:34:24 qznc wrote:
> On Tuesday, 6 August 2013 at 16:02:31 UTC, Jesse Phillips wrote:
> > On Tuesday, 6 August 2013 at 14:51:35 UTC, qznc wrote:
> >> My recent pull request [0] triggered some issue, which should
> >> get a bigger discussion:
> >> 
> >> Should Phobos version N also compile with DMD N-1?
> >> 
> >> In my opinion it should, because it makes Phobos development
> >> simpler. You don't need a self compiled dmd to fix bugs.
> >> 
> >> However, reality sometimes requires exceptions. I understand
> >> that sometimes Phobos uses a feature of dmd HEAD. That is why
> >> I said "should", but not "must". ;)
> >> 
> >> 
> >> [0]
> >> https://github.com/D-Programming-Language/phobos/pull/1454/files#r5601514
> > 
> > This doesn't sound related to the problem discussed. Phobos N
> > must compile with DMD N, that is a primary requirement. If
> > Phobos N compiles with DMD N-1, great but it can't fail in DMD
> > N.
> 
> Correct, Phobos N with DMD N is a "must". The question is,
> whether Phobos N with DMD N-1 is a "should".
> 
> For the pull request, the question is what goes into the
> guidelines. That should be discussed there, instead of here in
> the forums. ;)

We're really not worrying about whether Phobos N compiles with DMD N-1. What 
matters is that the current Phobos compiles with the current dmd. And I really 
don't see much reason to do otherwise. Phobos is always released together with 
dmd, so you're never going to be using an older dmd with a newer Phobos unless 
you're building the yourself and don't keep them in sync. The autotester tests 
the latest master only, and it would just be extra overhead for little to no 
gain to make it test against the previous release as well, especially when we 
do make changes that are not expected to work with the previous release, and I 
don't expect that to change. It's likely to become less frequent overtime (and 
is already less frequent than it used to be), but there is no requirement that 
the current druntime or Phobos compile with the previous release of dmd, and I 
don't expect that there will ever be such a requirement.

Anyone submitting pull requests to druntime or Phobos should be using the 
latest dmd, because that's what we're testing. If they happen to be able to 
get away with using the previous release, that's fine, but we make no guarantee 
that that will work and are not likely to put forth any effort to make it work.

- Jonathan M Davis