As I wrote that I came to the same conclusion, but decided to leave the rest in case.

On Thu, Nov 26, 2015 at 12:25 AM, GHC <ghc-devs@haskell.org> wrote:
#11028: Refactor ConDecl
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        Reporter:  simonpj           |                Owner:  alanz
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.2
      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 simonpj):

 >  Alternatively, everything except the `rnLHsType` in `rnConResult` can
 move to the type checking.

 That sounds exactly right.  `Note [Sorting out the result type]` in
 `RdrHsSyn` seems entirely redundant with the new `ConDeclGADT` form.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11028#comment:25>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler