[GHC] #9204: Conflicting definition in hs-boot file

[GHC]

#9204: Conflicting definition in hs-boot file
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        Reporter:  Feuerbach         |            Owner:
            Type:  bug               |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  Compiler          |          Version:  7.8.2
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
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Comment (by Feuerbach):

 If I add a role annotation to the hs-boot file, this works.

 My guess is that since the hs-boot doesn't have the complete information
 about the type, it cannot infer the phantom role of the parameter.

 Still, I wish I didn't have to deal with this. But if this isn't possible,
 at least the error message should suggest adding the role annotation to
 the hs-boot file.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9204#comment:1>
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