[GHC] #10890: Incorrect redundant import warning for type classes

[GHC]

#10890: Incorrect redundant import warning for type classes
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        Reporter:  quchen            |                Owner:
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:  8.0.1
       Component:  Compiler          |              Version:  7.10.2
      Resolution:  fixed             |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D1257
       Wiki Page:                    |
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Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"9376249b6b78610db055a10d05f6592d6bbbea2f/ghc" 9376249/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="9376249b6b78610db055a10d05f6592d6bbbea2f"
 Fix unused-import stuff in a better way

 The fix for Trac #10890 in commit 1818b48, namely
    Fix incorrect import warnings when methods with identical names are
 imported
 was wrong, as demonstrated by the new test T10890_2.  It suppressed
 far too many warnings!

 This patch fixes the original problem in a different way, by making
 RdrName.greUsedRdrName a bit cleverer.

 But this too is not really the Right Thing.  I think the Right Thing is
 to store the /GRE/ in the tcg_used_rdrnames, not the /RdrName/.  That
 would be a lot simpler and more direct.

 But one step at a time.
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10890#comment:14>
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