[GHC] #2851: Improve error message for failed deriving

[GHC]

#2851: Improve error message for failed deriving
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    Reporter:  guest                       |        Owner:  igloo           
        Type:  merge                       |       Status:  closed          
    Priority:  normal                      |    Milestone:                  
   Component:  Compiler (Type checker)     |      Version:  6.10.1          
    Severity:  minor                       |   Resolution:  fixed           
    Keywords:                              |   Difficulty:  Unknown         
    Testcase:  deriving/should_fail/T2851  |           Os:  Unknown/Multiple
Architecture:  Unknown/Multiple            |  
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Changes (by igloo):

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

Comment:

 Both merged

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2851#comment:9>
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