[GHC] #7541: Unavoidable duplicate constraint warning

[GHC]

#7541: Unavoidable duplicate constraint warning
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Reporter:  blamario                           |          Owner:                  
    Type:  bug                                |         Status:  new             
Priority:  normal                             |      Component:  Compiler        
 Version:  7.6.1                              |       Keywords:                  
      Os:  Unknown/Multiple                   |   Architecture:  Unknown/Multiple
 Failure:  Incorrect warning at compile-time  |      Blockedby:                  
Blocking:                                     |        Related:                  
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Comment(by simonpj@…):

 commit 5a6a223f855538112ec9d089425e34853fb3542b
 {{{
 Author: Simon Peyton Jones <simonpj at microsoft.com>
 Date:   Wed Jan 2 11:57:00 2013 +0000

     Add flag -fwarn-duplicate-constraints

     This fixes Trac #7541, and is on by default.
     Use -fno-warn-duplicate-constraints to switch it off.

  compiler/main/DynFlags.hs      |    5 ++++-
  compiler/typecheck/TcMType.lhs |    9 +++++----
  docs/users_guide/flags.xml     |    7 +++++++
  docs/users_guide/using.xml     |   19 +++++++++++++++++++
  4 files changed, 35 insertions(+), 5 deletions(-)
 }}}

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7541#comment:1>
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