[GHC] #12549: Panic on ":t datatypeName"

[GHC]

#12549: Panic on ":t datatypeName"
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        Reporter:  johnleo       |                Owner:
            Type:  bug           |               Status:  new
        Priority:  normal        |            Milestone:
       Component:  Compiler      |              Version:  8.1
      Resolution:                |             Keywords:
Operating System:  MacOS X       |         Architecture:  x86_64 (amd64)
 Type of failure:  None/Unknown  |            Test Case:
      Blocked By:                |             Blocking:
 Related Tickets:                |  Differential Rev(s):
       Wiki Page:                |
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Comment (by johnleo):

 Replying to [comment:5 mpickering]:
 > It's possible that the panic also happens in 8.0.1 because it is caused
 by an assertion failure. Assertions are not turned on in the released
 builds.

 Thanks, I didn't know that.  Here's an example of a function from Generics
 which also has strange unicode display behavior, but which does not cause
 a panic in 8.1:
 {{{
 :t (:*:)
 (:*:) ∷ ∀ {g ∷ ★ → *} {p} {f ∷ ★ → *}. f p → g p → (:*:) ★ f g p
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12549#comment:6>
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