[GHC] #12985: GHCi incorrectly reports the kind of unboxed tuples spliced in from Template Haskell

[GHC]

#12985: GHCi incorrectly reports the kind of unboxed tuples spliced in from
Template Haskell
-------------------------------------+-------------------------------------
        Reporter:  RyanGlScott       |                Owner:
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:  8.0.2
       Component:  Template Haskell  |              Version:  8.0.2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Other             |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #12976            |  Differential Rev(s):  Phab:D2886
       Wiki Page:                    |
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Changes (by facundo.dominguez):

 * status:  new => patch
 * cc: bgamari (added)
 * differential:   => Phab:D2886
 * milestone:   => 8.0.2


Comment:

 That patch is particularly fragile with functions which have a default
 case which doesn't fail.

 {{{
 f :: HsType name -> ...
 f (HsTyVar ...) =
 f (HsAppTy ...) =
 f _ = do not fail and continue
 }}}

 As the patch introduces a new case to all functions traversing types
 between renaming and typechecking, functions in the style of `f` make the
 omissions have surprising effects, of which this ticket was an instance.

 I submitted a fixup to phabricator. bgamari, this patch would have low
 risk to include in GHC 8.0.2 I think.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12985#comment:4>
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