[GHC] #12919: Equality not used for substitution

[GHC]

#12919: Equality not used for substitution
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        Reporter:  int-index         |                Owner:  goldfire
            Type:  bug               |               Status:  patch
        Priority:  highest           |            Milestone:  8.4.1
       Component:  Compiler (Type    |              Version:  8.0.1
  checker)                           |
      Resolution:                    |             Keywords:  TypeInType
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  GHC rejects       |            Test Case:
  valid program                      |  typecheck/should_compile/T12919
      Blocked By:                    |             Blocking:  14441
 Related Tickets:  #13643            |  Differential Rev(s):  Phab:D3848
       Wiki Page:                    |
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Comment (by Richard Eisenberg <rae@…>):

 In [changeset:"b47a6c3a6d9c5da341184824549a6a835c79de15/ghc" b47a6c3/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="b47a6c3a6d9c5da341184824549a6a835c79de15"
 Fix performance of flattener patch (#12919)

 This patch, authored by alexvieth and reviewed at D4451,
 makes performance improvements by critically optimizing parts
 of the flattener.

 Summary:
 T3064, T5321FD, T5321Fun, T9872a, T9872b, T9872c all pass.
 T9872a and T9872c show improvements beyond the -5% threshold.
 T9872d fails at 10.9% increased allocations.
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12919#comment:24>
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