[GHC] #15910: GHC missreports import as redundant.

[GHC]

#15910: GHC missreports import as redundant.
-------------------------------------+-------------------------------------
           Reporter:  AndreasK       |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:  8.6.3
          Component:  Compiler       |           Version:  8.6.2
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 In the following code GHC claims the first import is redundant.

 {{{
 import Data.Map (Map)

 import qualified Data.Map as M

 type MT = Map
 }}}


 {{{
 test.hs:5:1: warning: [-Wunused-imports]
     The qualified import of `Data.Map' is redundant
       except perhaps to import instances from `Data.Map'
     To import instances alone, use: import Data.Map()
   |
 5 | import qualified Data.Map as M
 }}}


 Reproduceable on 8.4 and HEAD at least.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15910>
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