[GHC] #12509: ghci -XSafe fails in an inscrutable way

[GHC]

#12509: ghci -XSafe  fails in an inscrutable way
-------------------------------------+-------------------------------------
        Reporter:  int-e             |                Owner:  RolandSenn
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:  SafeHaskell
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:  make test
                                     |  TEST=T12509
      Blocked By:                    |             Blocking:
 Related Tickets:  #13385, #14342    |  Differential Rev(s):
       Wiki Page:                    |  https://gitlab.haskell.org/ghc/ghc/merge_requests/241
-------------------------------------+-------------------------------------
Changes (by RolandSenn):

 * differential:  Gitlab Merge Request 23 =>
     https://gitlab.haskell.org/ghc/ghc/merge_requests/241


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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12509#comment:11>
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