ghc panic

As ghc requested I am reporting this... All I can say right now is that I am tracking down a bug involving overlapping instances.

ghc: panic! (the 'impossible' happened)
  (GHC version 7.4.1 for i386-unknown-linu
	tcTyVarDetails
    ( t{tv acw0} [tv] :: ghc-prim:GHC.Prim.*{(w) tc 34d} )

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

Edited Mar 09, 2019 by Ian Lynagh -

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

Admin message

ghc panic