[GHC] #8774: Transitivity of Auto-Specialization

[GHC]

#8774: Transitivity of Auto-Specialization
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        Reporter:  crockeea          |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.6.3
      Resolution:                    |             Keywords:  Inlining
Operating System:  Linux             |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #5928, #8668,     |  Differential Rev(s):
  #8099                              |
       Wiki Page:                    |
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Comment (by bgamari):

 @erikd, plop the `Foo` and `Main` modules given in the ticket description
 in appropriately named files and compile `Main` with `ghc -ddump-simpl
 -dsuppress-idinfo -O`. You should see no `Foo a`s in the simplified core;
 instead you should see a nicely specialized definition of `plus` with all
 `Foo`s should be instantiated at `Int`. There should be no calls to the
 polymorphic `Foo.plus`.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8774#comment:8>
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