[Hackage] #474: cabal-install needlessly reinstalls an existing package

[Hackage]

#474: cabal-install needlessly reinstalls an existing package
---------------------------------+------------------------------------------
  Reporter:  judah               |        Owner:         
      Type:  defect              |       Status:  new    
  Priority:  normal              |    Milestone:         
 Component:  cabal-install tool  |      Version:  1.6.0.1
  Severity:  normal              |     Keywords:         
Difficulty:  unknown             |   Ghcversion:         
  Platform:                      |  
---------------------------------+------------------------------------------
 With ghc-6.10.1, Cabal-1.6.0.1 and cabal-install-0.6 (or HEAD):

 {{{
 $ cabal install cabal-install --dry-run -v
 [..]
 Reading available packages...
 Resolving dependencies...
 [..]
 selecting Cabal-1.6.0.1 (installed or hackage)
 [..]
 selecting process-1.0.1.1 (installed or hackage) and discarding
 filepath-1.0,
 process-1.0.0.0 and 1.0.1.0
 [..]
 In order, the following would be installed:
 Cabal-1.6.0.1 (reinstall) changes: process-1.0.1.0 -> 1.0.1.1
 cabal-install-0.6.0 (new package)
 }}}

 The `ghc` package depends on `Cabal-1.6.0.1` and `process-1.0.1.0`, so
 rebuilding `Cabal` to depend on `process-1.0.1.1` causes `ghc` to have
 inconsistent dependencies.  In particular:

 {{{
 $ cabal install cabal-install
 [succeeds, but reinstalls Cabal-1.6.0.1]
 $ cabal install ghci-haskeline
 Resolving dependencies...
 cabal: dependencies conflict: ghc-6.10.1 requires process ==1.0.1.0
 however
 process-1.0.1.0 was excluded because ghc-6.10.1 requires process ==1.0.1.1
 }}}

 It seems like the right thing to do would be to use `process-1.0.1.0` when
 building `cabal-install`.

-- 
Ticket URL: <http://hackage.haskell.org/trac/hackage/ticket/474>
Hackage <http://haskell.org/cabal/>
Hackage: Cabal and related projects