[GHC] #11371: Bogus in-scope set in substitutions

[GHC]

#11371: Bogus in-scope set in substitutions
-------------------------------------+-------------------------------------
        Reporter:  simonpj           |                Owner:  niteria
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.2.1
       Component:  Compiler          |              Version:  7.10.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #11360            |  Differential Rev(s):  phab:D1792,
       Wiki Page:                    |  phab:D1801, phab:D1802
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Comment (by Bartosz Nitka <niteria@…>):

 In [changeset:"685398ebc5c8377597714cd8c3e97439d32e3a02/ghc"
 685398eb/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="685398ebc5c8377597714cd8c3e97439d32e3a02"
 Use the correct in-scope set in coercionKind

 The free vars of `ty2` need to be in scope to satisfy the substitution
 invariant.
 As far as I can tell we don't have the free vars of `ty2` when
 substituting, so unfortunately we have to compute them.

 Test Plan: ./validate

 Reviewers: austin, bgamari, simonpj, goldfire

 Subscribers: thomie, simonmar

 Differential Revision: https://phabricator.haskell.org/D2024

 GHC Trac Issues: #11371
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11371#comment:53>
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