[GHC] #8386: AMP warning on "hiding (join)"

[GHC]

#8386: AMP warning on "hiding (join)"
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        Reporter:  monoidal                      |            Owner:
            Type:  bug                           |           Status:  new
        Priority:  normal                        |        Milestone:
       Component:  Compiler                      |          Version:  7.7
      Resolution:                                |         Keywords:
Operating System:  Unknown/Multiple              |     Architecture:
 Type of failure:  Incorrect warning at          |  Unknown/Multiple
  compile-time                                   |       Difficulty:
       Test Case:                                |  Unknown
        Blocking:                                |       Blocked By:
                                                 |  Related Tickets:
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Comment (by quchen):

 I don't think there is an easy fix for this.

 When you write `import Plreude hiding (join)` right now, you're hiding a
 function that is not even in `Prelude`. GHC does not issue a warning here
 though; it just silently adds nothing to the hiding list. For that reason,
 you cannot check whether `join` is hidden from an import when it's not in
 there in the first place.

 See also http://www.haskell.org/haskellwiki/Functor-Applicative-
 Monad_Proposal#Future_Prelude_names

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8386#comment:1>
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