Panic when building Crucible

I've encountered a panic, which GHC has asked me to report:

[19 of 21] Compiling Lang.Crucible.LLVM.Translation ( src/Lang/Crucible/LLVM/Translation.hs, dist/build/Lang/Crucible/LLVM/Translation.p_o )

<no location info>: error:
    ghc: panic! (the 'impossible' happened)
  (GHC version 8.4.3 for x86_64-unknown-linux):
        isUnliftedType
  r_a4Zsg :: TYPE rep_a4Zsf
  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

This was when compiling crucible-llvm revision 186mfb7wlz with GHC 8.4.3.

I'm building in Nix with a sandbox, so this should be easily reproducible. The Nix files are available here: https://github.com/siddharthist/galois-haskell-nix/tree/ghc-bug. Just run nix-build -A haskellPackages.crucible-llvm.

Trac metadata

Trac field	Value
Version	8.4.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information

Admin message

Panic when building Crucible