GHCi displays the kinds of unboxed tuples incorrectly

This can be reproduced in GHCi 8.0.2 or HEAD. First, a preamble:

$ inplace/bin/ghc-stage2 --interactive
GHCi, version 8.1.20161208: http://www.haskell.org/ghc/  :? for help
Loaded GHCi configuration from /home/rgscott/.ghci
λ> :set -fprint-explicit-runtime-reps -fprint-explicit-kinds -fprint-explicit-foralls -XUnboxedTuples -XTemplateHaskell -XMagicHash 
λ> :m + GHC.Exts Language.Haskell.TH Language.Haskell.TH.Lib Language.Haskell.TH.Syntax

The kind of (#,#) is reported correctly:

(#,#) :: forall (k0 :: RuntimeRep) (k1 :: RuntimeRep).
         TYPE k0 -> TYPE k1 -> TYPE 'UnboxedTupleRep

But when you give it an argument, it seems to default TYPE k1 to * for some reason!

λ> :k (#,#) Int#
(#,#) Int# :: * -> TYPE 'UnboxedTupleRep

This is a blatant lie, as this kind-checks:

λ> :k (#,#) Int# Int#
(#,#) Int# Int# :: TYPE 'UnboxedTupleRep

The effect is even more noticeable when you throw TemplateHaskell into the mix:

λ> :k $(unboxedTupleT 2)
$(unboxedTupleT 2) :: * -> * -> TYPE 'UnboxedTupleRep
λ> :k $(unboxedTupleT 2) Int#
$(unboxedTupleT 2) Int# :: * -> TYPE 'UnboxedTupleRep
λ> :k $(conT (unboxedTupleTypeName 2))
$(conT (unboxedTupleTypeName 2)) :: * -> * -> TYPE 'UnboxedTupleRep
λ> :k $(conT (unboxedTupleTypeName 2)) Int#
$(conT (unboxedTupleTypeName 2)) Int# :: * -> TYPE 'UnboxedTupleRep

All of these kinds should be reporting the RuntimeReps that GHC is //actually// using under the hood.

Trac metadata

Trac field	Value
Version	8.0.2
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	GHCi
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