[GHC] #12780: Calling "do nothing" type checker plugin affects type checking when it shouldn't

[GHC]

#12780: Calling "do nothing" type checker plugin affects type checking when it
shouldn't
-------------------------------------+-------------------------------------
        Reporter:  clinton           |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC rejects       |  Unknown/Multiple
  valid program                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #11525            |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Changes (by darchon):

 * related:   => #11525


Comment:

 https://ghc.haskell.org/trac/ghc/ticket/11525 describes what's going on

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12780#comment:4>
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