[Hackage] #376: Allow constraint on using installed package versions

[Hackage]

#376: Allow constraint on using installed package versions
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  Reporter:  duncan              |        Owner:        
      Type:  enhancement         |       Status:  new   
  Priority:  normal              |    Milestone:        
 Component:  cabal-install tool  |      Version:  HEAD  
  Severity:  normal              |   Resolution:        
  Keywords:                      |   Difficulty:  normal
Ghcversion:  6.8.3               |     Platform:        
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Comment (by Peaker):

 The wxcore package currently has a bug that prohibits it from being
 installed user-locally.

 This forced me to install it system-wide.
 However, this means that it is built with only system-wide packages
 available as dependencies.

 When I want to install another package that depends on wxcore that is not
 system-wide, it thinks it should rebuild wxcore to make use of the better
 dependencies, and fails.

 In order to avoid this problem, I had to manually purge wxcore from
 cabal's cache/listing.

 It would be nice if I could ask cabal to use an already installed package
 rather than replace it, somehow.

-- 
Ticket URL: <http://hackage.haskell.org/trac/hackage/ticket/376#comment:1>
Hackage <http://haskell.org/cabal/>
Hackage: Cabal and related projects