[GHC] #13795: :kind! is not expanding type synonyms anymore

[GHC]

#13795: :kind! is not expanding type synonyms anymore
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        Reporter:  Hjulle            |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  GHCi              |              Version:  8.0.2
      Resolution:                    |             Keywords:  newcomer
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):

 Did `:kind!` ever expand synonyms?

 The user manual claims that it does, but I can see no evidence that it
 ever did.

 Do we want it to expand synonyms?  I think probably yes.

 If so, the right spot is here in `TcRnDriver`:
 {{{
        ; ty' <- if normalise
                 then do { fam_envs <- tcGetFamInstEnvs
                         ; let (_, ty')
                                 = normaliseType fam_envs Nominal ty
                         ; return ty' }
                 else return ty ;
 }}}
 After calling `normaliseType`, call `Type.expandTypeSynonyms`.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13795#comment:2>
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