Impredicativity bug: forall not hoisted properly

Try compiling this:

{-# OPTIONS -fglasgow-exts #-}
module Bug where
	data T a = MkT

	out :: forall a. T a -> ()
	out MkT = ()

	inHoisted :: forall r. () -> (forall a. T a -> r) -> r
	inHoisted _ foo = foo MkT

	inUnhoisted :: () -> forall r. (forall a. T a -> r) -> r
	inUnhoisted _ foo = foo MkT
	
	testHoisted :: ()
	testHoisted = inHoisted () out
	
	testUnhoisted :: ()
	testUnhoisted = inUnhoisted () out

Results:

Bug.hs:18:17:
    Couldn't match expected type `T a -> ()'
           against inferred type `forall a1. T a1 -> r'
      Expected type: (T a -> ()) -> ()
      Inferred type: (forall a1. T a1 -> r) -> r
    In the expression: inUnhoisted () out
    In the definition of `testUnhoisted':
        testUnhoisted = inUnhoisted () out

Expected: testUnhoisted to compile, just like testHoisted

Trac metadata

Trac field	Value
Version	6.6
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
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Operating system	Unknown
Architecture	Unknown