Rebuilding ghc changes interface hashes?

Simon Marlow marlowsd at
Wed Apr 6 10:02:41 CEST 2011

On 05/04/2011 23:14, Matthias Kilian wrote:
> On Tue, Apr 05, 2011 at 08:51:52PM +0100, Simon Marlow wrote:
>>> On Tue, Apr 05, 2011 at 09:59:23PM +0530, Joachim Breitner wrote:
>>>> Also, the initial upload was built using ghc-6.12.1, while the upload
>>>> now is build with ghc-7.0.2. Given that it is a two-stage compiler, I
>>>> assume that the output should be identical, but it seems not to be the
>>>> case.
>>> Changing the bootstrapping compiler changes the ABIs. The same can
>>> happen if you interrupt and restart the build.
>> In general changes can creep in randomly, there's no direct link between
>> changing the bootstrap compiler and getting different compilation
>> results (as far as I know), but there are some small elements of
>> randomness.
> Oh, I confused those two problems again :-( But memories come back,
> and IIRC the problem with the bootstrapping compiler is caused by
> the "Booter version" (as printed by ghc --info) passed up to the
> stage2 compiler. Wasn't the plan (about a year ago) to remove this?

I don't think that is actually causing any problems.  It just means that 
stage2 claims to have been bootstrapped by whatever you used to build 
stage1.  Maybe that was intentional (Ian?).


> If time permits, I'll send a patch in a few days, but I first have
> to follow the switch to git, and I also want to update our (OpenBSDs)
> ports to ghc-7.0.3 and hp-2011.2.
> Ciao,
> 	Kili

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