[GHC] #11120: Missing type representations

[GHC]

#11120: Missing type representations
-------------------------------------+-------------------------------------
        Reporter:  goldfire          |                Owner:
            Type:  bug               |               Status:  patch
        Priority:  high              |            Milestone:  8.0.1
       Component:  Compiler          |              Version:  7.11
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D1769
       Wiki Page:                    |
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Comment (by RyanGlScott):

 This might have been mentioned already (hard to tell, since I don't really
 understand the technical details here), but it's still possible to trigger
 GHC panics pretty easily due to (what I assume are) inadequate type
 representations:

 {{{
 $ inplace/bin/ghc-stage2 --interactive
 GHCi, version 8.1.20160113: http://www.haskell.org/ghc/  :? for help
 Loaded GHCi configuration from /nfs/nfs4/home/rgscott/.ghci
 λ> :set -XTypeInType -XMagicHash
 λ> :m + Data.Typeable GHC.Prim GHC.Exts
 λ> data CharHash = CharHash Char#
 λ> typeOf (Proxy :: Proxy 'CharHash)
 ghc-stage2: panic! (the 'impossible' happened)
   (GHC version 8.1.20160109 for x86_64-unknown-linux):
         tyConRep Char#

 Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

 λ> typeOf (Proxy :: Proxy 'C#)
 GHC error in desugarer lookup in Ghci2:
   Can't find interface-file declaration for variable tc'C#
     Probable cause: bug in .hi-boot file, or inconsistent .hi file
     Use -ddump-if-trace to get an idea of which file caused the error
 ghc-stage2: panic! (the 'impossible' happened)
   (GHC version 8.1.20160109 for x86_64-unknown-linux):
         initDs IOEnv failure

 Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11120#comment:14>
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