[Hackage] #884: Changed dependencies in locally installed packages ignord

[Hackage]

#884: Changed dependencies in locally installed packages ignord
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  Reporter:  nomeata             |        Owner:         
      Type:  enhancement         |       Status:  new    
  Priority:  normal              |    Milestone:         
 Component:  cabal-install tool  |      Version:  1.8.0.6
  Severity:  normal              |     Keywords:         
Difficulty:  unknown             |   Ghcversion:         
  Platform:                      |  
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 Hello,

 in Debian, I have patched yesod-json-0.2.1 to depend on aeson instead of
 aeson-native, because we want only one aeson and blaze-textual package in
 Debian.

 Still, if I use cabal install to install a package that depends on yesod-
 json, it wants to re-build yesod-json against the -native variants. It
 seems that cabal install does not take the actual dependencies of
 installed packages into account and uses the Hackage provided information
 for them as well.

 What it should do instead is: If a dependency of some packages that is to
 be installed can be fulfilled by a locally installed package, and none of
 its dependencies (as known by ghc-pkg) have to be rebuild, then this
 package should be used. Only if the package in question has to be rebuild,
 the dependencies according to hackage should be taken into account.

 The work around in Debian is to bump the version number, adding a vendor
 level (0.2.1.0.1), but it would be nice if this could be avoided.

-- 
Ticket URL: <http://hackage.haskell.org/trac/hackage/ticket/884>
Hackage <http://haskell.org/cabal/>
Hackage: Cabal and related projects