[GHC] #12123: GHC crashes when calling typeRep on a promoted tuple

[GHC]

#12123: GHC crashes when calling typeRep on a promoted tuple
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           Reporter:  MikeIzbicki    |             Owner:
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.0.1
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 The following code (asking for the typeRep of a promoted tuple) causes GHC
 to crash.

 {{{
 import Data.Typeable
 import Data.Proxy

 x = typeRep (Proxy::Proxy '(Int,Int))
 }}}

 The error message is:
 {{{
 [1 of 1] Compiling Main             ( ../Bug.hs, interpreted )
 GHC error in desugarer lookup in Main:
   Can't find interface-file declaration for variable $tc'(,)
     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 8.1.20160518 for x86_64-unknown-linux):
         initDs IOEnv failure
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12123>
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