some refinement-typed expressions can be refactored to avoid dynamic calls

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Regarding ticket #3974, one favored practice to deal with dynamic calls involves:

a) know where they occur: -Ylog:cleanup -Ydebug

b) manually create a named class/interface, and use that as the explicit return type of the expression instead of a refinement type.

Should the refactoring in (b) above be part of the compiler, or is it for lint? In some cases a block-local class would be added, othertimes a template-level one (with the same visibility as the LHS of the assignment?). And, after adding a named type (before CleanUp) retyping is needed. Any cons other than that?

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Imported From: https://issues.scala-lang.org/browse/SI-3975?orig=1 Reporter: @magarciaEPFL

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@magarciaEPFL said: Replying to [ticket:3975 magarcia]:

The example in ticket #3974 does not show method-chaining of dynamic calls, but they are also amenable to refactoring as the following example shows:

    new AnyRef {
      def abc { ... }
    }.abc

formulated using "atomic evaluation" becomes

  {
    val tmp = new AnyRef {
      def abc { ... }
    }
    tmp.abc
  }

thus making room for the class definition:

  {
    class Boilerplate extends AnyRef {
      def abc { ... }
    }
    val tmp = new Boilerplate
    tmp.abc
  }

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@magarciaEPFL said: The recipe above does away with reflective calls in several situations, but some remain. For them, a refinement type reference can sometimes be traced back to a single allocation site, thus guaranteenig that a named class can be inserted instead. Looks like deciding whether one such usage can be "traced back to a single allocation site" is a task for points-to analysis. For example, the following POPL 2011 accepted paper presents recent ideas on that:

Smaragdakis Y., Bravenboer M., Lhot�k O., [[BR]] Pick Your Contexts Well: Understanding Object-Sensitivity.[[BR]] http://www.cs.umass.edu/~yannis/typesens-prelim.pdf

Just for those students reading this who might be looking for a thesis topic :)