[GHC] #12158: ghc: panic! (the 'impossible' happened) translateConPatVec: lookup

[GHC]

#12158: ghc: panic! (the 'impossible' happened)  translateConPatVec: lookup
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        Reporter:  wozgonon          |                Owner:  gkaracha
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
                                     |  PatternMatchWarnings
Operating System:  Windows           |         Architecture:  x86_64
 Type of failure:  Compile-time      |  (amd64)
  crash                              |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 Aha.  Quite right.  In general GHCi lets you over-ride an old definition
 for `f` with a new one.  But here it doesn't make sense to override a
 record selector with a function.

 Someone should think this through.  It's a bit fiddly, but I don't think
 it's really hard.  Eg. in GHCi don't allow a let-binding override a record
 selector.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12158#comment:8>
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