[GHC] #4200: UndecidableInstances not needed for equality constraints

[GHC]

#4200: UndecidableInstances not needed for equality constraints
-------------------------------------------------+--------------------------
  Reporter:  simonpj                             |          Owner:                  
      Type:  bug                                 |         Status:  closed          
  Priority:  normal                              |      Milestone:  7.0.1           
 Component:  Compiler                            |        Version:  6.12.3          
Resolution:  fixed                               |       Keywords:                  
  Testcase:  indexed-types/should_compile/T4200  |      Blockedby:                  
Difficulty:                                      |             Os:  Unknown/Multiple
  Blocking:                                      |   Architecture:  Unknown/Multiple
   Failure:  None/Unknown                        |  
-------------------------------------------------+--------------------------
Changes (by simonpj):

  * status:  new => closed
  * testcase:  => indexed-types/should_compile/T4200
  * resolution:  => fixed


Comment:

 Fixed by
 {{{
 Sun Sep 19 17:26:23 GMT Daylight Time 2010  simonpj at microsoft.com
   * Loosen the conditions for -XUndecidableInstances; fixes Trac #4200

     M ./compiler/typecheck/TcMType.lhs -8 +6
 }}}

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4200#comment:2>
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