[GHC] #15152: Core Lint error in ill-typed GADT code

[GHC]

#15152: Core Lint error in ill-typed GADT code
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        Reporter:  tdammers          |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler          |              Version:  8.4.2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #11066            |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"f49f90bb84b12515366de9b8184644b5c3798901/ghc" f49f90b/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="f49f90bb84b12515366de9b8184644b5c3798901"
 Tidy up error suppression

 Trac #15152 showed that when a flag turned an error into a warning, we
 were still (alas) suppressing subequent errors; includign their
 essential addTcEvBind.  That led (rightly) to a Lint error.

 This patch fixes it, and incidentally tidies up an ad-hoc special
 case of out-of-scope variables (see the old binding for
 'out_of_scope_killer' in 'tryReporters').

 No test, because the problem was only shown up when turning
 inaccessible code into a warning.
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15152#comment:4>
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