[GHC] #6134: Incorrect ambiguity error with functional dependencies

[GHC]

#6134: Incorrect ambiguity error with functional dependencies
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    Reporter:  diatchki                 |       Owner:                           
        Type:  bug                      |      Status:  new                      
    Priority:  normal                   |   Milestone:                           
   Component:  Compiler (Type checker)  |     Version:  7.4.1                    
    Keywords:                           |          Os:  Unknown/Multiple         
Architecture:  Unknown/Multiple         |     Failure:  GHC rejects valid program
  Difficulty:  Unknown                  |    Testcase:                           
   Blockedby:                           |    Blocking:                           
     Related:                           |  
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Comment(by simonpj@…):

 commit dc0ef28faa47edc41681494b8d5210213e866740
 {{{
 Author: Simon Peyton Jones <simonpj at microsoft.com>
 Date:   Fri Jun 8 09:43:12 2012 +0100

     Make the ambiguity check more conservative so that it does not reject
 valid programs

     See Note [The ambiguity check for type signatures] in TcMType,
     and Trac #6134, which this change fixes.

     A bit of refactoring as usual.

  compiler/typecheck/TcMType.lhs |  248
 ++++++++++++++++++++++------------------
  1 files changed, 135 insertions(+), 113 deletions(-)
 }}}

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/6134#comment:2>
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