[GHC] #12737: T12227 is failing on ghc-8.0

[GHC]

#12737: T12227 is failing on ghc-8.0
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        Reporter:  ezyang            |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.0.2
       Component:  Visual Haskell    |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by bgamari):

 Indeed the patch I cited in comment:2 is the patch that adds the failing
 test. Sadly I don't seeing any relevant patches to
 `compiler/util/Pretty.hs` missing from `ghc-8.0`. Tracking this one down
 may be a bit tricky. Thankfully the difference is quite large, so
 comparing ticky profiles from `ghc-8.0` and `master` around the time
 should be illuminating.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12737#comment:4>
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