[GHC] #5642: Deriving Generic of a big type takes a long time and lots of space

[GHC]

#5642: Deriving Generic of a big type takes a long time and lots of space
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        Reporter:  basvandijk        |                Owner:  bgamari
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.0.1
       Component:  Compiler          |              Version:  7.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:  T5642
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by bgamari):

 For the record this sounds quite similar to #8095 in that the compiler
 seems to be creating long strings of coercions (although here the
 simplifier doesn't even seem capable of eliminating them).

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5642#comment:24>
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