[GHC] #15695: Core Lint error, from -fobject-code + defer type errors + pattern synonyms + other stuff

[GHC]

#15695: Core Lint error, from -fobject-code + defer type errors + pattern synonyms
+ other stuff
-------------------------------------+-------------------------------------
        Reporter:  Iceland_jack      |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler          |              Version:  8.6.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"02b303eed0170983921877801e57f55d012db301/ghc"
 02b303ee/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="02b303eed0170983921877801e57f55d012db301"
 Do not mark CoVars as dead in the occur-anal

 For years we have been marking CoVars as dead, becuase we
 don't gather occurrence info from types.  This is obviously
 wrong and caused Trac #15695.

 See Note [Do not mark CoVars as dead] in OccurAnal.
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15695#comment:3>
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