[GHC] #4983: Warning about redundant import is wrong when hiding identifiers in order to avoid export ambiguities

[GHC]

#4983: Warning about redundant import is wrong when hiding identifiers in order to
avoid export ambiguities
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        Reporter:  Lemming                       |            Owner:
            Type:  bug                           |           Status:
        Priority:  normal                        |  closed
       Component:  Compiler                      |        Milestone:
      Resolution:  wontfix                       |          Version:  7.0.1
Operating System:  Unknown/Multiple              |         Keywords:
 Type of failure:  Incorrect warning at          |     Architecture:
  compile-time                                   |  Unknown/Multiple
       Test Case:                                |       Difficulty:
        Blocking:                                |  Unknown
                                                 |       Blocked By:
                                                 |  Related Tickets:
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Changes (by tibbe):

 * difficulty:   => Unknown


Comment:

 This problem popped up in the containers package which quite reasonably
 does:

 {{{
 module Data.IntMap (fold) where

 import Data.IntMap.Base  -- exports foldr
 import Prelude hiding (foldr)

 fold = foldr
 }}}

 This means that GHC HEAD doesn't validate against containers anymore. We
 can work around the issue, but GHC is to blame here.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4983#comment:5>
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