Shake fails test with GHC 7.10 RC3

Austin Seipp austin at
Sat Mar 21 20:45:04 UTC 2015

Yes, this was what I was afraid of; an introduced regression in the RC
2-to-3 period, which IMO makes the bug a bit more serious. Also, this
bug in particular looks like it manifests in a fairly nasty way, and
having it catch people for the final release seems a bit worrisome.

I also just remembered that the Haddock documentation for 7.10.1 is
still broken; I've been tracking the bug today, but I need to sync up
with the Haddock maintainers to discuss more. I really think this one
needs to be fixed.

So I also suggest we postpone for a few days to fix these two things,
if possible.

On Sat, Mar 21, 2015 at 6:55 AM, Neil Mitchell <ndmitchell at> wrote:
> Interesting result. I've just attached a much smaller test case to the
> ticket - it would be good to see if that fails or passes with RC2, or
> breaks at the same point.
> The fact that there does seem to be a regression between RC2 and RC3
> (either a regression itself, or making a previous bug easier to hit)
> makes me think that a release might not be such a great idea.
> Thanks, Neil
> On Sat, Mar 21, 2015 at 11:35 AM, Herbert Valerio Riedel
> <hvriedel at> wrote:
>> On 2015-03-21 at 08:21:20 +0100, Herbert Valerio Riedel wrote:
>>> On 2015-03-21 at 07:56:32 +0100, Neil Mitchell wrote:
>>> [...]
>>>> 3) I tested with GHC RC1 and GHC RC2, both of which were fine. The fact no
>>>> one else hit this with RC2 might just be because its a very recent
>>>> regression.
>>> We -- and by that I don't mean myself... :) -- could git-bisect between
>>> RC2 and RC3 here (semi-)automatically (i.e. maybe unattended if it's
>>> scriptable) if your test-case (even if it's not minimal) reliably
>>> triggers the bug...
>> I scripted up a test and git-bisected between RC2 and RC3, and the
>> following commit is the one where `shake-test oracle test` starts
>> failing
>> ...which sadly is a rather large patch :-/


Austin Seipp, Haskell Consultant
Well-Typed LLP,

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