[GHC] #16013: :kind! accepts unsaturated type aliases

[GHC]

#16013: :kind! accepts unsaturated type aliases
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           Reporter:  dmwit          |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:  8.6.3
          Component:  Compiler       |           Version:  8.4.3
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 Here's a ghci session:

 {{{
 > :set -XTypeFamilies -XPolyKinds
 > type family Id (a :: k)
 > type instance Id a = a
 > type Foo x = Maybe
 > :kind! Id Foo
 Id Foo :: *
 = Id Foo
 }}}

 I think the final `:kind!` query should throw an error instead,
 complaining that `Foo` hasn't been given enough arguments. (But even if
 you disagree, and think it should be allowed, `*` is clearly not the right
 kind!)

 Using a normal type alias in place of the type family for `Id` also allows
 the query incorrectly, though it does at least report a sensible kind.

 Although I think it shouldn't matter, I have checked with `-ignore-dot-
 ghci` to make sure I haven't accidentally turned LiberalTypeSynonyms on.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16013>
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