ApplicativeDo easily foiled with `pure`

ApplicativeDo fails to desugar do blocks ending with pure. For instance,

{-# LANGUAGE ApplicativeDo #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}

newtype MaybeA a = MaybeA (Maybe a)
                 deriving (Show, Functor, Applicative)

main = print $ do x <- MaybeA $ Just 42
                  pure x

However, if the final pure is changed to return things work as expected.

Trac metadata

Trac field	Value
Version	8.0.1-rc2
Type	Bug
TypeOfFailure	OtherFailure
Priority	high
Resolution	Unresolved
Component	Compiler (Type checker)
Test case
Differential revisions
BlockedBy
Related
Blocking
CC	simonmar
Operating system
Architecture