[GHC] #12430: TypeFamilyDependencies accepts invalid injectivity annotation

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Mon Oct 15 17:19:12 UTC 2018


#12430: TypeFamilyDependencies accepts invalid injectivity annotation
-------------------------------------+-------------------------------------
        Reporter:  vagarenko         |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:
       Component:  Compiler (Type    |              Version:  8.0.1
  checker)                           |             Keywords:
      Resolution:                    |  InjectiveFamilies
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC accepts       |  Unknown/Multiple
  invalid program                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Changes (by RyanGlScott):

 * keywords:   => InjectiveFamilies


Comment:

 Even simpler:

 {{{#!hs
 {-# LANGUAGE TypeFamilyDependencies #-}
 module Bug where

 type C a = Int
 type family F x = y | y -> x where
   F x = C x
 }}}

 I'm on this.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12430#comment:3>
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