New scheme for implicit classes that can be top level

[adriaanm]

Suggested by @retronym on Scala-user

[...] scheme to encode the implicit modifier into the name of a some class. For instance, we could do something like:

implicit class RichString(val s: String) {
   /*synthetic*/ class Implicit$ // added by the compiler
}

There is precedent for adding synthetic inner classes (e.g javac does to add to the signatures of "access constructors": https://gist.github.com/retronym/8ca8026f5b7eb981b53f5c8923d50f54)

[DarkDimius]

Adding a class to represent a single bit sounds very inefficient size-wise.

[retronym]

Implicit classes are rare enough to let us consider it, I think. Certainly worth trying alternatives, though