On Mon, Oct 15, 2012 at 04:48:20PM +0200, Henning Thielemann wrote:
I try to compile a package with many dependencies using GHC-7.5.20120426 in order to check whether #5970 is resolved. This turns out to be difficult because this temporary GHC version seems to use packages with the same version as their counterparts on Hackage but different content. For example GHC-7.5.20120426 is bundled with unix-2.5.1.0 and bytestring-0.10.0.0. However the unix-2.5.1.0 on Hackage excludes bytestring-0.10.0.0. Thus cabal-install refuses to install something that depends on unix-2.5.1.0. Another example: Both GHC-7.4.1 and GHC-7.5.20120426 are bundled with base-4.5.0.0. However in GHC-7.5, Num is no longer superclass of Bits. I think such a change requires a version bump to base-4.6.
In my opinion the condition should be that if you publish a package on Hackage then there should not be a package with the same version but different content somewhere else. Thus I propose that package versions are increased immediately in the repository according to the PVP if something is changed. That's how I handle versioning for my private packages, too.
And in the ticket Simon Marlow said:
I definitely think we should change the policy - in fact I typically bump a library as soon as I change it, to avoid this problem. Is the policy written down anywhere? It wouldn't be hard to change, right?
The policy is not written down TTBOMK, and is easy to change. However, one thing to bear in mind is upper-bound dependencies. Package maintainers are unlikely to update their upper bounds to follow changes in the development repos, so if we bump directory to 1.3.0.0 then cabal will not be able to install any package that depends on "directory < 1.3". While this can be manually worked around, it makes it harder to investigate bug reports with the HEAD. What exactly would the new policy be? Is it just the last component that is bumped, or is the version number bumped according to the PvP? Is the version bump relative to what was in the repo before, so after the 1.2.0.1 directory release we might have 1.3.0.0, 1.4.0.0 and 1.5.0.0 in the repo before 1.5.0.0 is release, skipping 1.3 and 1.4? Or do you check what the last release was and only bump if necessary relative to that (so once the repo reaches 1.3.0.0 it will not be bumped further until a release is made)? Would we also follow this policy for packages we don't maintain (perhaps with ghc-only version bumps if necessary)? Thanks Ian