[GHC] #13099: recompilation can fail to recheck type family instance consistency

[GHC]

#13099: recompilation can fail to recheck type family instance consistency
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        Reporter:  rwbarton          |                Owner:  rwbarton
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.1
      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 rwbarton):

 I'm not sure whether you meant LHS rather than RHS; in any case the
 consistency check depends on both.

 > As always with these sorts of bugs, a failing test case helps a lot!

 OK, I'll add a failing test case and then probably release the ticket.
 (But not immediately.)

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13099#comment:5>
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