[GHC] #6001: Wrong diagnostics for instance signature mismatch

[GHC]

#6001: Wrong diagnostics for instance signature mismatch
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  Reporter:  heisenbug                          |          Owner:  pcapriotti      
      Type:  bug                                |         Status:  closed          
  Priority:  normal                             |      Milestone:  7.6.1           
 Component:  Compiler                           |        Version:  7.5             
Resolution:  fixed                              |       Keywords:                  
        Os:  Unknown/Multiple                   |   Architecture:  Unknown/Multiple
   Failure:  Incorrect warning at compile-time  |     Difficulty:  Unknown         
  Testcase:  typecheck/should_fail/T6001        |      Blockedby:                  
  Blocking:                                     |        Related:                  
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Comment(by simonpj):

 Indeed.  The new error message is absolutely right:
 {{{
 NumGADT.hs:10:18:
     Method signature does not match class; it should be
     fromInteger :: Integer -> Day c
     In the instance declaration for `Num (Day c)'
 }}}
 So with the above patch (thanks Paolo) all is good.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/6001#comment:7>
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