Rebuilding ghc changes interface hashes?

Ian Lynagh igloo at
Wed Apr 6 13:40:45 CEST 2011

On Tue, Apr 05, 2011 at 08:51:52PM +0100, Simon Marlow wrote:
> On 05/04/11 17:51, Matthias Kilian 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)

compiler/stage2/build/Config.hs includes cBooterVersion, so if you boot
with a different version then you get different code => different ABI.

We could just remove this. In theory, stage2 won't be affected by the
bootstrapping compiler at all anyway.

Alternatively, if we make a config file (as we were discussing for
putting the paths to gcc and ar in) then it could go in there, and then
wouldn't be part of the ABI.


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