Data Parallel "Impossible happened" compiler error

When I attempted to compile my vectorized code , I got the following message:

ghc -c -Odph -fcpr-off -fdph-seq newprop.hs
ghc: panic! (the 'impossible' happened)
  (GHC version 6.12.1 for i386-apple-darwin):
	sumTyCon 11

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

Edited Mar 09, 2019 by Ian Lynagh -

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