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

[GHC]

#11371: Bogus in-scope set in substitutions
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        Reporter:  simonpj           |                Owner:  niteria
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.4.1
       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 Marge Bot <ben+marge-bot@…>):

 In [changeset:"60b03adea8cc55ff65fbf6458487c3baf12bb0a1/ghc"
 60b03ade/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="60b03adea8cc55ff65fbf6458487c3baf12bb0a1"
 Change the warning in substTy back to an assertion

 We'd like to enforce the substitution invariant (Trac #11371).
 In a492af06d326453 the assertion was downgraded to a warning;
 I'm restoring the assertion and making the calls that
 don't maintain the invariant as unchecked.
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11371#comment:64>
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