[GHC] #10488: Inconsistent reduction of type family

[GHC]

#10488: Inconsistent reduction of type family
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        Reporter:  goldfire          |                   Owner:
            Type:  bug               |                  Status:  patch
        Priority:  highest           |               Milestone:  7.10.2
       Component:  Compiler          |                 Version:  7.10.1
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  None/Unknown      |  Unknown/Multiple
      Blocked By:                    |               Test Case:
 Related Tickets:  Phab:D955         |                Blocking:
                                     |  Differential Revisions:
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Comment (by Richard Eisenberg <eir@…>):

 In [changeset:"761fb7c4869a081da7320e4307dcb947b5ed95d1/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="761fb7c4869a081da7320e4307dcb947b5ed95d1"
 Fix #10488 by unwrapping type synonyms.

 Summary:
 Previously, I had forgotten to unwrap vanilla type synonyms in the
 "flattener" that is used around the closed-type-family apartness
 check.

 Test Plan: validate

 Reviewers: austin

 Subscribers: bgamari, thomie

 Differential Revision: https://phabricator.haskell.org/D955

 GHC Trac Issues: #10488
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10488#comment:2>
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