[GHC] #15186: ghc 8.4.2 panic in profiling build

[GHC]

#15186: ghc 8.4.2 panic in profiling build
-------------------------------------+-------------------------------------
           Reporter:  kquick         |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.4.2
           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:
-------------------------------------+-------------------------------------
 When building our crucible-llvm library
 (https://github.com/GaloisInc/crucible) with profiling enabled, we
 encounter the following:

 {{{
 [19 of 21] Compiling Lang.Crucible.LLVM.Translation (
 src/Lang/Crucible/LLVM/Translation.hs,
 dist/build/Lang/Crucible/LLVM/Translation.p_o )
 ghc: panic! (the 'impossible' happened)
   (GHC version 8.4.2 for x86_64-unknown-linux):
         isUnliftedType
   r_a4IqS :: TYPE rep_a4IqR
   Call stack:
       CallStack (from HasCallStack):
         callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in
 ghc:Outputable
         pprPanic, called at compiler/types/Type.hs:1939:10 in ghc:Type

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

 Procedure to reproduce:
 {{{
 $ git clone https://github.com/GaloisInc/crucible
 $ cd crucible/crucible-llvm
 $ ghc --version
 The Glorious Glasgow Haskell Compilation System, version 8.4.2
 $ cabal --version
 cabal-install version 2.0.0.1
 compiled using version 2.0.1.0 of the Cabal library
 $ cabal configure --enable-library-profiling
 $ cabal build
 }}}

 Note: the llvm-pretty dependency on Hackage is not compatible with GHC
 8.4.2; use the latest from the github repo at http://github.com/elliottt
 /llvm-pretty.  The crucible and what4 dependencies come from sibling
 subdirectories in the same crucible checkout.

 This builds successfully when using GHC 8.2.2 instead.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15186>
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