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

[GHC]

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

 * cc: roshats (added)
 * component:  Compiler => GHCi
 * os:  Windows => Unknown/Multiple
 * architecture:  x86_64 (amd64) => Unknown/Multiple


Comment:

 When you actually use a `let` binding though, it works fine:
 {{{
 Prelude> data Stock = Stock {name :: String, ric :: String, price ::
 Float}
 Prelude> let price Stock{name=name,ric=ric,price=price} = price * 2
 Prelude> price (Stock "abc" "def" 12.3)
 24.6
 }}}

 So this is another problem with the toplevel definitions feature
 introduced in GHCi 8.0 (#7253). See also #12091.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12158#comment:9>
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