[GHC] #12430: TypeFamilyDependencies accepts invalid injectivity annotation

[GHC]

#12430: TypeFamilyDependencies accepts invalid injectivity annotation
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        Reporter:  vagarenko         |                Owner:  (none)
            Type:  bug               |               Status:  patch
        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):  Phab:D5228
       Wiki Page:                    |
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Comment (by Ben Gamari <ben@…>):

 In [changeset:"26e81e90281685af37c8f2cf149c242b4039117a/ghc"
 26e81e90/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="26e81e90281685af37c8f2cf149c242b4039117a"
 Fix #12430 by expanding type synonyms in injTyVarsOfType

 We weren't expanding type synonyms when determining the
 injective type variables of a type, leading to certain non-injective
 families being mistakenly labeled as injective (#12430). Easily fixed
 with a tactical use of `coreView`.

 Test Plan: make test TEST=T12430

 Reviewers: bgamari, goldfire

 Reviewed By: goldfire

 Subscribers: goldfire, rwbarton, carter

 GHC Trac Issues: #12430

 Differential Revision: https://phabricator.haskell.org/D5228
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12430#comment:5>
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