Upper bound on "time" in Cabal causes build failure

[Toby Goodwin]

Hi cabal developers,

Wasn't sure what best to do with this - please let me know if you'd rather I emailed it elsewhere, or opened an issue against the github project, or...

I'm trying to build haskell-platform-2014.2 from source, with the latest cabal:

  cabal-install version 1.20.0.4
  using version 1.20.0.3 of the Cabal library 

The build plan it constructs for the hptool sandbox includes Cabal-1.2.4! (That's not a typo.) The problem seems to be that it chooses time-1.5, and then discovers that all recent versions of Cabal have the constraint "time < 1.5", so digs up this fossil from the attic.

So I think there are two problems here. The small and simple one is that we need a release of Cabal with "time < 1.6" - you appear to have this in the master branch already; can it go on the 1.20 branch? Do you want me to create an issue / pull request?

The larger problem is that cabal should have found a better build plan. I'm naive about the internals of dependency resolution, but I would have expected it to prefer taking time back 1 release over taking Cabal back 18. It would also be nice if it could have deduced that Cabal-1.2.4 wasn't actually going to build with recent ghc versions.

Thanks for your time,

Toby.