[GHC] #12727: ghc: panic! (the 'impossible' happened) - piResultTy

[GHC]

#12727: ghc: panic! (the 'impossible' happened) - piResultTy
-------------------------------------+-------------------------------------
        Reporter:  ocharles          |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.2-rc1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by ocharles):

 We've had a few more panics today, each different:

 {{{
 [248 of 278] Compiling Handler.Auth     ( src/Handler/Auth.hs,
 dist/build/Handler/Auth.o )
 ghc: panic! (the 'impossible' happened)
   (GHC version 8.0.1.20161117 for x86_64-unknown-linux):
         Iface Lint failure
   In interface for Data.ByteString.Internal
   Unfolding of $fShowByteString_$cshow
     <no location info>: warning:
         In the expression: $trModule2
                              (unpackChars x_apbxX) (: @ Char shows6 ([] @
 Char))
         Non-function type in function position
         Fun type: TrName
         Arg type: [Char]
         Arg: unpackChars x_apbxX
   $fShowByteString_$cshow = \ (x_apbxX :: ByteString) ->
                               : @ Char
                                 shows6
                                 ($trModule2 (unpackChars x_apbxX) (: @
 Char shows6 ([] @ Char)))
   Iface expr = \ (x :: ByteString) ->
                : @ Char
                  shows6
                  (showLitString (unpackChars x) (: @ Char shows6 ([] @
 Char)))
 }}}

 and

 {{{
 [215 of 278] Compiling Foundation       ( Foundation.hs,
 dist/build/Foundation.o )
 ghc: panic! (the 'impossible' happened)
   (GHC version 8.0.1.20161117 for x86_64-unknown-linux):
         tyThingTyCon Identifier ‘$fEnumIsolationLevel’
 }}}

 I'll continue to see if I can get any sort of repro on this.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12727#comment:6>
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