[GHC] #11203: Kind inference with SigTvs is wrong

[GHC]

#11203: Kind inference with SigTvs is wrong
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        Reporter:  goldfire          |                Owner:  (none)
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  7.10.2
  checker)                           |
      Resolution:  fixed             |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
                                     |  polykinds/T11203
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Richard Eisenberg <rae@…>):

 In [changeset:"3910d3e2f8b3084f6f6de3d9aeb8d8ed20670245/ghc"
 3910d3e2/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="3910d3e2f8b3084f6f6de3d9aeb8d8ed20670245"
 Add some commentary re: fix to #11203

 The fix for #11203 prohibits duplicate SigTvs in non-CUSK kind
 signatures by checking for duplicates after type inference is
 done. This works well. GHC also checks for duplicate SigTvs
 after working with partial type signatures (another place where
 SigTvs arise). However, neither fix eliminates this whole class
 of problems (because doing so would be heavier than we would
 like). So, this comment adds a warning to users of newSigTyVar
 to be aware of problems with duplicates.
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11203#comment:13>
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