[GHC] #11148: T9563 doesn't pass with reversed uniques

[GHC]

#11148: T9563 doesn't pass with reversed uniques
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        Reporter:  niteria           |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"1160dc516f8b27249d819665883409ee270a743f/ghc" 1160dc5/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="1160dc516f8b27249d819665883409ee270a743f"
 Fix egregious error in eta-reduction of data families

 This terrible and long-standing bug was shown up by Trac #11148.
 We are trying to eta-reduce a data family instance, so that we
 can then derive Functor or Generic.  But we were assuming, for
 absolutely not reason whatsoever, that the type variables were
 lined up in a convenient order.  The fact that it ever worked
 was a fluke.

 This patch fixes it properly.  Main change is in eta_reduce
 in TcInstDcls.tcDataFamInstDecl
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11148#comment:4>
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