cabal insists on template-haskell-2.6.0.0, breaking hackage builds

[LeventErkok]

A detailed discussion is in this haskell-cafe thread:

   http://www.haskell.org/pipermail/haskell-cafe/2012-July/102352.html

I'm not entirely sure if this is a pure cabal issue. In particular the version of ghc currently installed on hackage and/or the setup on hackage is also of suspect. In relation to cabal, Ross says:

  With ghc 7.4.1, cabal-install 0.13.3 and Cabal 1.14.0,

 % cabal install --avoid-reinstalls sbv-2.2

fails to find a plan without reinstalls, and recommends --solver=modular.

 % cabal install --solver=modular --avoid-reinstalls sbv-2.2

 reinstalls template-haskell-2.6.0.0, which breaks the GHC installation.

 I've added the suggested --constraint='template-haskell==2.7.0.0'
option as a workaround, but it seems the --avoid-reinstalls option is
being ignored.

[kosmikus]

I haven't seen anything yet that suggests there's a Cabal or cabal-install problem involved. 0.13.3 isn't an official version. I haven't been able to reproduce that cabal-install --avoid-reinstalls suggests a reinstall.

The only issue I can see here is that cabal-install should refuse installing new versions of template-haskell completely, in the same way it refuses to install ghc-prim or base. However, rather than having a large hardcoded list of built-in packages for GHC, I'd like to have a robust algorithm to detect such packages.

[hvr]

Fyi, I've updated all template-haskell releases on hackage to include bounds on base. Maybe this helps.

[23Skidoo]

This looks to have been fixed by updated version bounds on Hackage, so closing. Please reopen if the issue persists.