Panic! make_exp (App _ (Coercion _)) when compiled with -fext-core
An attempt to compile the attached file with 7.6.2 (and 7.4.2) with "-O2 -fext-core" leads to:
ghc: panic! (the 'impossible' happened)
(GHC version 7.6.2 for x86_64-unknown-linux):
make_exp (App _ (Coercion _))