[Hackage] #925: Unused constraints result in "no available version"

Hackage cvs-ghc at haskell.org
Wed Mar 7 06:21:00 CET 2012

#925: Unused constraints result in "no available version"
  Reporter:  snoyberg       |        Owner:          
      Type:  defect         |       Status:  new     
  Priority:  normal         |    Milestone:          
 Component:  Cabal library  |      Version:
  Severity:  normal         |     Keywords:          
Difficulty:  unknown        |   Ghcversion:          
  Platform:                 |  
 When testing out my recently released cabal nirvana[1], Greg Weber pointed
 out than when building a package that does not use all of the constraints
 in the Nirvana file, you get a message such as:

     cabal: There is no available version of authenticate that satisfies

 I confirmed that this happens with command-line constraints as well. A
 simple test case is to go into a non-Yesod project and run:

     cabal install --constraint "yesod >= 0.10"

 Unfortunately, this prevents nirvana from being of any use at all, which
 was our best shot at avoiding dependency hell.

 [1] http://hackage.haskell.org/package/cabal-nirvana

Ticket URL: <http://hackage.haskell.org/trac/hackage/ticket/925>
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