[GHC] #15805: Bug in anyRewritableTyVar

[GHC]

#15805: Bug in anyRewritableTyVar
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        Reporter:  ningning          |                Owner:  ningning
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #14363            |  Differential Rev(s):  Phab:D5263
       Wiki Page:                    |
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Comment (by Ben Gamari <ben@…>):

 In [changeset:"a7f64c6cbfc5562adff207945576d1c9db2a58d9/ghc"
 a7f64c6c/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="a7f64c6cbfc5562adff207945576d1c9db2a58d9"
 Fix TcType.anyRewritableTyVar

 Summary:
 This patch fixes #15805, where we found that
 `TcType.anyRewritableTyVar` has one wrong case.

 Besides the fix, it also:
 - removed some unnecessary `ASSERT2(tcIsTcTyVar...)` in `TcType`, as now
 we have
      `tcIsTcTyVar = isTyVar`.
 - fixed some comments

 Test Plan: ./validate

 Reviewers: goldfire, simonpj, bgamari

 Reviewed By: simonpj

 Subscribers: rwbarton, carter

 GHC Trac Issues: #15805

 Differential Revision: https://phabricator.haskell.org/D5263
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15805#comment:3>
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