[Hackage] #705: Non-deterministic behaviour when overlapping packages are installed

[Hackage]

#705: Non-deterministic behaviour when overlapping packages are installed
---------------------------------+------------------------------------------
  Reporter:  guest               |        Owner:         
      Type:  defect              |       Status:  new    
  Priority:  normal              |    Milestone:         
 Component:  cabal-install tool  |      Version:  1.8.0.2
  Severity:  normal              |     Keywords:         
Difficulty:  unknown             |   Ghcversion:         
  Platform:                      |  
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 See [http://stackoverflow.com/questions/3119782/mysterious-cabal-install-
 problems].

 This user took a standard Haskell Platform install, installed a new
 version of the time package, and then installed random.  The random
 package was rebuilt and installed against the new time package.  However,
 re-running `cabal install random` installs random again; it doesn't reach
 a fixed point.

 The problem (I presume) is that when cabal-install merges the package
 databases it chooses which `random-1.0.0.2` to use non-deterministically.
 In fact it seems to depend on the exact package Ids, because I get
 different results with GHC 6.12.2 where the package Ids of the two
 `random-1.0.0.2` packages are ordered differently.

 I realise there are larger issues about how to do resolution here, but I
 think at least we should make cabal-install deterministic, and preferably
 idempotent.

-- 
Ticket URL: <http://hackage.haskell.org/trac/hackage/ticket/705>
Hackage <http://haskell.org/cabal/>
Hackage: Cabal and related projects