"the impossible happened" when compiling Types.Substitutions
Ran into this when trying to compile elm from git:
$ cabal install
Resolving dependencies...
Configuring Elm-0.5.0.1...
Building Elm-0.5.0.1...
Preprocessing library Elm-0.5.0.1...
[ 3 of 26] Compiling Types.Substitutions ( src/Types/Substitutions.hs, dist/build/Types/Substitutions.o )
ghc: panic! (the 'impossible' happened)
(GHC version 7.6.1 for i386-unknown-linux):
compiler/codeGen/CgCase.lhs:572:15-61: Irrefutable pattern failed for pattern ((CoreSyn.DEFAULT,
deflt_absC) : others)
Failed to install Elm-0.5.0.1