[GHC] #14624: HEAD panic in ghc:DsForeign: toCType

[GHC]

#14624: HEAD panic in ghc:DsForeign: toCType
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        Reporter:  tianxiaogu        |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.2
      Resolution:                    |             Keywords:
Operating System:  Linux             |         Architecture:  x86_64
 Type of failure:  Compile-time      |  (amd64)
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by RyanGlScott):

 A simpler way to trigger the panic that doesn't involve any Template
 Haskell:

 {{{#!hs
 {-# LANGUAGE CApiFFI #-}
 {-# LANGUAGE MagicHash #-}
 {-# LANGUAGE UnliftedFFITypes #-}
 module Foo where

 import GHC.Exts (Int#)

 foreign import capi safe "bar" bar :: Int# -> Int#
 }}}

 {{{
 $ /opt/ghc/8.2.2/bin/ghc Foo.hs
 [1 of 1] Compiling Foo              ( Foo.hs, Foo.o )
 ghc: panic! (the 'impossible' happened)
   (GHC version 8.2.2 for x86_64-unknown-linux):
         toCType
   Int#
   Call stack:
       CallStack (from HasCallStack):
         prettyCurrentCallStack, called at
 compiler/utils/Outputable.hs:1133:58 in ghc:Outputable
         callStackDoc, called at compiler/utils/Outputable.hs:1137:37 in
 ghc:Outputable
         pprPanic, called at compiler/deSugar/DsForeign.hs:726:17 in
 ghc:DsForeign
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14624#comment:1>
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