Panic with partial class definition

Compiling a class with partial definition fails:

class A _ => B a

ghc: panic! (the 'impossible' happened)
  (GHC version 7.10.3 for x86_64-apple-darwin):
	rnHsTyKi HsWildcardTy

Trac metadata

Trac field	Value
Version	7.10.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture