id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	os	architecture	failure	difficulty	testcase	blockedby	blocking	related
7035	`deriving instance Generic (HsExpr Id)` raises panic	Daniel Schuessler	dreixel	"Input file:

{{{

{-# LANGUAGE FlexibleInstances, DeriveGeneric, StandaloneDeriving #-}
module GHCGeneric where

import GHC
import GHC.Generics

deriving instance Generic (HsExpr Id)

}}}

Result:

{{{
GHCi, version 7.4.2: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
[1 of 1] Compiling GHCGeneric       ( /home/daniel/dev/dataflow/GHCGeneric.hs, interpreted )
ghc: panic! (the 'impossible' happened)
  (GHC version 7.4.2 for i386-unknown-linux):
        tcTyVarDetails ( id{tv a3cX} [tv] :: *{(w) tc 34d} )

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

Regards,[[BR]]
Daniel"	bug	closed	normal	7.8.1	Compiler	7.4.2	duplicate			Linux	Unknown/Multiple	Compile-time crash	Unknown				7255