GHCi 8.2 simply ignores TH splice using datatype with a forall'd kind signature

This is a pretty bizarre behavior I've noticed recently that only happens in GHC 8.2 or later. If you try to use a Template Haskell splice with a very particular feature (a datatype whose kind uses forall) in GHCi, then GHCi will flat-out ignore it!

$ /opt/ghc/8.2.1/bin/ghci
GHCi, version 8.2.0.20170427: http://www.haskell.org/ghc/  :? for help
Loaded GHCi configuration from /home/rgscott/.ghci
λ> :set -XGADTs -XTypeInType -XTemplateHaskell -XRankNTypes 
λ> import Language.Haskell.TH (stringE, pprint)
λ> import Data.Kind (Type)
λ> $([d| data Foo :: forall a. a -> Type where MkFoo :: Foo Int |] >>= stringE . pprint)
λ> print (5 + length $([d| data Foo :: forall a. a -> Type where MkFoo :: Foo Int |] >>= stringE . pprint))
λ> 5
5
λ> it
5
λ> $([d| data Foo :: forall a. a -> Type where MkFoo :: Foo Int |] >>= stringE . pprint)
λ> it
5

Notice how none of my attempts to use the splice seemed to register with GHCi.

This isn't really a regression //per se//, since GHC 8.0.1 nor 8.0.2 even allowed you to get that far:

$ /opt/ghc/8.0.2/bin/ghci
GHCi, version 8.0.2: http://www.haskell.org/ghc/  :? for help
Loaded GHCi configuration from /home/rgscott/.ghci
λ> :set -XGADTs -XTypeInType -XTemplateHaskell -XRankNTypes 
λ> import Language.Haskell.TH (stringE, pprint)
λ> import Data.Kind (Type)
λ> $([d| data Foo :: forall a. a -> Type where MkFoo :: Foo Int |] >>= stringE . pprint)

<interactive>:4:3: error:
    Exotic form of kind not (yet) handled by Template Haskell
      forall a. a -> Type

Trac metadata

Trac field	Value
Version	8.2.1-rc1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Template Haskell
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