GHC panics when contexts are put late in function types

Here's a simple transcript from ghci:

Prelude> :m + Data.List
Prelude Data.List> :t genericLength :: [a] -> Num b => b
ghc: panic! (the 'impossible' happened)
  (GHC version 6.10.3 for x86_64-unknown-linux):
	TcTyFuns.flattenType: unexpected PredType

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

Trac metadata

Trac field	Value
Version	6.10.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler (Type checker)
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