[GHC] #16300: Make TH always reify data types with explicit return kinds

[GHC]

#16300: Make TH always reify data types with explicit return kinds
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        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Template Haskell  |              Version:  8.6.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by goldfire):

 I favor keeping the no-mixed-constructors and no-kind-sig-without-GADT-
 constructors restrictions: they keep TH closer to Haskell. I feel like
 every time TH diverges from Haskell, we regret it later.

 So, returning to the original question: how about non-`Type`-kinded
 datatypes/newtypes always reify as GADTs? The choice of syntax in
 reification is immaterial, so let's just change it.

 Also, we should reject the example in comment:2, as it would be rejected
 in Haskell.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16300#comment:4>
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