[GHC] #13651: Invalid redundant pattern matches with -XTypeFamilyDependencies

[GHC]

#13651: Invalid redundant pattern matches with -XTypeFamilyDependencies
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        Reporter:  crockeea          |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.2
      Resolution:                    |             Keywords:
                                     |  InjectiveFamilies
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 RyanGlScott):

 As it turns out, that's not the full story. The first commit in which the
 program in this ticket compiled without warnings was
 eb55ec2941239dee05afc6be818b129efe51660e (Refactor functional dependencies
 a bit).

 Commit adb565aa74582969bbcc3b411d6d518b1c76c3cf, on the other hand, did
 squash needless pattern-match warnings in some other, similar programs,
 such as this one:

 {{{#!hs
 {-# LANGUAGE TypeFamilies #-}
 module Bug2 where

 foo :: Int ~ Bool => a -> a
 foo x = x
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13651#comment:5>
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