Inferred type is rejected

Consider

class C a where
 op :: a -> ()

f x = op [x]

we get

Foo.hs:14:1: error:
    Non type-variable argument in the constraint: C [t]
    (Use FlexibleContexts to permit this)
    When checking that ‘f’ has the inferred type
      f :: forall t. C [t] => t -> ()

Arguably, if FlexibleContexts is not on, we should not infer a type that will immediately be rejected.

Trac metadata

Trac field	Value
Version	7.10.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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