[GHC] #13474: GHC HEAD regression: Prelude.!!: index too large

[GHC]

#13474: GHC HEAD regression: Prelude.!!: index too large
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        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.2.1
       Component:  Compiler          |              Version:  8.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC rejects       |  Unknown/Multiple
  valid program                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by bgamari):

 Ahh yes. I **knew** there was a reason why we needed that logic. I'm about
 to merge Phab:d3316 and after I do so I'll add a test and confirm that
 this is fixed. If not I'll likely just revert the commit mentioned in
 comment:3 on `ghc-8.2`.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13474#comment:5>
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