[GHC] #13089: GHC panics when importing Array from Data.Array.Repa (was: GHC panics on some imports from the Repa package)

[GHC]

#13089: GHC panics when importing Array from Data.Array.Repa
-------------------------------------+-------------------------------------
        Reporter:  cbaatz            |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:  x86_64
                                     |  (amd64)
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Description changed by cbaatz:

@@ -9,1 +9,5 @@
- import           Data.Array.Repa     hiding ((++))
+ import           Data.Array.Repa     ((:.) (..), DIM1, DIM2, U, Z (..))
+
+ and I've confirmed that it panics with:
+
+ import           Data.Array.Repa     (Array)

New description:

 I stumbled upon a GHC panic for some reason. The error message is below.
 The error disappears when I replace:

 import           Data.Array.Repa     ((:.) (..), Array, DIM1, DIM2, U, Z
 (..))

 with

 import           Data.Array.Repa     ((:.) (..), DIM1, DIM2, U, Z (..))

 and I've confirmed that it panics with:

 import           Data.Array.Repa     (Array)

 ```
 ghc: panic! (the 'impossible' happened)
   (GHC version 8.0.1 for x86_64-apple-darwin):
         filterImports/combine
   (Array,
    Array{Array, AByteString, ACursored, ADelayed, AForeignPtr,
 AInterleave, ASmall, APart, AUnboxed, AUndefined, AVector, cursoredExtent,
 loadCursor, makeCursor, shiftCursor},
    Nothing)
   (Array,
    Source{Source, Array, deepSeqArray, extent, index, linearIndex,
 unsafeIndex, unsafeLinearIndex},
    Nothing)
 ```

--

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13089#comment:2>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler