[GHC] #13506: Spurious extra error message due to functional dependencies

[GHC]

#13506: Spurious extra error message due to functional dependencies
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        Reporter:  gelisam           |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.0.2
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect         |  Unknown/Multiple
  error/warning at compile-time      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"48daaaf0bba279b6e362ee5c632de69ed31ab65d/ghc" 48daaaf/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="48daaaf0bba279b6e362ee5c632de69ed31ab65d"
 Don't report fundep wanted/wanted errors

 This makes GHC drop derived FunDep errors when they
 are come from wanted/wanted interactions.  Much along
 the lines of "don't rewrite wanteds with wanteds".

 See TcRnTypes Note [Dropping derived constraints]
 and the new code in isDroppableDerivedLoc.

 Fixes Trac #13506.
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13506#comment:2>
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