Rebuilding ghc changes interface hashes?

[Ian Lynagh]

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.


Thanks
Ian