FullParameterization

Provides methods to produce fully parameterized versions of instance methods, where the this of the enclosing class is abstracted out in an extra leading $this parameter and type parameters of the class become additional type parameters of the fully parameterized method.

Example usage scenarios are:

• extension methods of value classes
• implementations of trait methods
• static protected accessors
• local methods produced by tailrec transform

Note that the methods lift out type parameters of the class containing the instance method, but not type parameters of enclosing classes. The fully instantiated method therefore needs to be put in a scope "close" to the original method, i.e. they need to share the same outer pointer. Examples of legal positions are: in the companion object, or as a local method inside the original method.

Note: The scheme does not handle yet methods where type parameter bounds depend on value parameters of the enclosing class, as in:

class C(val a: String) extends AnyVal {
  def foo[U <: a.type]: Unit = ...
}

The expansion of method foo would lead to

def foo$extension[U <: $this.a.type]($this: C): Unit = ...

which is not typable. Not clear yet what to do. Maybe allow PolyTypes to follow method parameters and translate to the following:

def foo$extension($this: C)[U <: $this.a.type]: Unit = ...