[Hackage] #120: misleading error message from cabal when versions differ

[Hackage]

#120: misleading error message from cabal when versions differ
-----------------------------+----------------------------------------------
  Reporter:  igloo at earth.li  |        Owner:                 
      Type:  defect          |       Status:  closed         
  Priority:  normal          |    Milestone:                 
 Component:  Cabal library   |      Version:  1.1.6          
  Severity:  normal          |   Resolution:  fixed          
  Keywords:                  |   Difficulty:  easy (<4 hours)
Ghcversion:  6.6             |     Platform:  Linux          
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Changes (by duncan):

  * status:  new => closed
  * resolution:  => fixed

Comment:

 It now adds a header to the file and checks it again when reading. The
 header  is a line like:

 {{{
 Saved package config for foo-1.0 written by Cabal-1.3.7 using ghc-6.8
 }}}

 It checks this header when reading back the config. If the Cabal versions
 do not match you'll get this error:

 {{{
 cabal: You need to re-run the 'configure' command. The version of Cabal
 being used has changed (was Cabal-1.3.6, now Cabal-1.3.7).
 }}}

 If additionally the compiler versions do not match then you get:

 {{{
 cabal: You need to re-run the 'configure' command. The version of Cabal
 being used has changed (was Cabal-1.3.6, now Cabal-1.3.7). Additionally
 the compiler is different (was ghc-6.8, now ghc-6.9) which is probably
 the cause of the problem.
 }}}

 Of course it does not help for older Cabal versions which lacked this
 check but it's the best we can do and should help in future.

-- 
Ticket URL: <http://hackage.haskell.org/trac/hackage/ticket/120#comment:2>
Hackage <http://haskell.org/cabal/>
Hackage: Cabal and related projects