[GHC] #13267: Constraint synonym instances

[GHC]

#13267: Constraint synonym instances
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        Reporter:  ezyang            |                Owner:  (none)
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.1
  checker)                           |
      Resolution:  fixed             |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  GHC accepts       |            Test Case:
  invalid program                    |  polykinds/T13267
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Ryan Scott <ryan.gl.scott@…>):

 In [changeset:"740ecda32116abe84b6d7d4786b3e2ad9c8ba2a4/ghc" 740ecda/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="740ecda32116abe84b6d7d4786b3e2ad9c8ba2a4"
 Observe #13267 in release notes

 I noticed some code in the wild that broke due to the validity checking
 introduced in #13267, so we should be proactive and warn about it in the
 8.2
 release notes.
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13267#comment:7>
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