Parse error on curried context of instance declaration

Assume we have the following classes:

class C1 a; class C2 a; class C3 a; class C4 a

GHC allows you to write a type with an uncurried context, as in:

foo :: (C1 a, C2 b, C3 c) => a -> b -> c

It also allows you to write a type with a curried context, as in:

foo :: C1 a => C2 b => C3 c => a -> b -> c

However it is not allowed to use this curried style of contexts in instance declarations, as in:

instance C1 a => C2 b => C3 c => C4 (SomeType a b c) 

Is this intentional?

Trac metadata

Trac field	Value
Version	6.12.2
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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