GHC 7.4.2 on Ubuntu Trusty

[Yitzchak Gale]

Resurrecting this thread:

My impression was that Edward's suggestion was a simple and
obvious solution to the problem of previous GHC versions quickly
becoming orphaned and unbuildable. But Austin thought that this
thread was stuck.

Would Edward's suggestion be difficult to implement for any
reason? Specifically, right now would be the time to do it, and
it would mean:

1. Create a 7.8.5 branch.
2. Tweak the stage 1 Haskell sources to build with 7.10 and tag
3. Create only a source tarball and upload it to the download
site

Thanks,
Yitz


On Wed, Oct 29, 2014 at 12:10 AM, Edward Z. Yang wrote:
> Excerpts from Yitzchak Gale's message of 2014-10-28 13:58:08 -0700:
>> How about this: Currently, every GHC source distribution
>> requires no later than its own version of GHC for bootstrapping.
>> Going backwards, that chops up the sequence of GHC versions
>> into tiny incompatible pieces - there is no way to start with a
>> working GHC and work backwards to an older version by compiling
>> successively older GHC sources.
>>
>> If instead each GHC could be compiled using at least one
>> subsequent version, the chain would not be broken. I.e.,
>> always provide a compatibility flag or some other reasonably
>> simple mechanism that would enable the current GHC to
>> compile the source code of at least the last previous released
>> version.
>
> Here is an alternate proposal: when we make a new major version release,
> we should also make a minor version release of the previous series, which
> is prepped so that it can compile from the new major version.  If it
> is the case that one version of the compiler can compile any other
> version in the same series, this would be sufficient to go backwards.
>
> Concretely, the action plan is very simple too: take 7.6 and apply as
> many patches as is necessary to make it compile from 7.8, and cut
> a release with those patches.
>
> Edward