[GHC] #5820: defining instance in GHCi leads to duplicated instances

[GHC]

#5820: defining instance in GHCi leads to duplicated instances
---------------------------------+------------------------------------------
  Reporter:  guest               |          Owner:                  
      Type:  bug                 |         Status:  merge           
  Priority:  high                |      Milestone:  7.4.2           
 Component:  GHCi                |        Version:  7.4.1-rc1       
Resolution:  fixed               |       Keywords:                  
        Os:  Unknown/Multiple    |   Architecture:  Unknown/Multiple
   Failure:  None/Unknown        |     Difficulty:  Unknown         
  Testcase:  ghci/scripts/T5820  |      Blockedby:                  
  Blocking:                      |        Related:                  
---------------------------------+------------------------------------------

Comment(by simonpj):

 This patch does not merge cleanly on the 7.4 branch, so I propose that we
 do not fix it on the branch.  It only affects instances declared at the
 GHCi prompt, and maybe we can manage without them working properly.

 If this is going to ruin your life, yell.

 Simon

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5820#comment:7>
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