[GHC] #4494: Another regression with type families

[GHC]

#4494: Another regression with type families
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    Reporter:  rl                       |        Owner:                                    
        Type:  bug                      |       Status:  merge                             
    Priority:  normal                   |    Milestone:                                    
   Component:  Compiler (Type checker)  |      Version:  7.1                               
    Keywords:                           |     Testcase:  indexed-types/should_compile/T4494
   Blockedby:                           |   Difficulty:                                    
          Os:  Unknown/Multiple         |     Blocking:                                    
Architecture:  Unknown/Multiple         |      Failure:  GHC rejects valid program         
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Changes (by simonpj):

  * status:  new => merge
  * testcase:  => indexed-types/should_compile/T4494


Comment:

 Fixed by
 {{{
 Mon Nov 15 12:15:40 GMT 2010  simonpj at microsoft.com
   * Ensure that unification variables alloc'd during solving are
 untouchable

   This fixes Trac #4494.  See Note [Extra TcsTv untouchables] in
 TcSimplify.

     M ./compiler/typecheck/TcCanonical.lhs -2 +2
     M ./compiler/typecheck/TcInteract.lhs -1 +9
     M ./compiler/typecheck/TcSMonad.lhs -8 +25
     M ./compiler/typecheck/TcSimplify.lhs -23 +73
 }}}
 Pls merge.

 Simon

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4494#comment:9>
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