[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
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #13962            |  Differential Rev(s):
       Wiki Page:                    |
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Changes (by RyanGlScott):

 * related:   => #13962


Comment:

 `:kind` deliberately allows unsaturated uses of type synonyms and type
 families—see
 [https://downloads.haskell.org/~ghc/8.6.3/docs/html/users_guide/ghci.html
 #ghci-cmd-:kind this section] of the users' guide. Many folks find it
 quite handy to be able to query the kinds of type synonyms with `:kind`
 (e.g., `:kind Id`), but disallowing unsaturated type synonyms/families
 //carte blanche// would prevent `:kind Id` from working, so a special case
 was added to allow it in that particular scenario.

 (Also note that this has been previously discussed in #13962.)

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16013#comment:2>
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