panic in idInfoToAmode with -O

The attached program causes GHC panic:

$ ghc-7.3.20110710 -O -fforce-recomp HList.hs
[1 of 1] Compiling Main             ( HList.hs, HList.o )
ghc: panic! (the 'impossible' happened)
  (GHC version 7.3.20110710 for x86_64-unknown-linux):
	idInfoToAmode: void ww{v s1UG} [lid]

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

Not passing -O or commenting out hNth (Next p) l = ... makes the panic disappear.

Trac metadata

Trac field	Value
Version	7.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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