Propagate the "real" type of an opaque type alias to the Reflection API

[gzoller]

minimized example

opaque type PhoneNumber = String
case class Person( phone: PhoneNumber )

For a serialization library I'm working on, I can reflect on Person and get information on its fields, i.e. phone. I can know that its type is PhoneNumber. I can't (today) learn that PhoneNumber's "real" type is String.

The serializer would need this to handle field phone as a String for serialization purposes.

Compilation output

Today the reflected TypeRef for field phone's type is something like this:

TypeRef(TermRef(TermRef(ThisType(TypeRef(NoPrefix,module class com)),module mypkg),Dog$package),PhoneNumber)

expectation

Somewhere in the TypeRef, add information about PhoneNumber's base type. Please (please) not just a label "String" or something flat like that. I need to be able to continue reflecting on the base type, especially if it isn't a primitive type! (A wrapped TypeRef?)

[gzoller]

Working on a PR for this. I think I may have something working.

[gzoller]

PR submitted: HERE

[nicolasstucki]

Closed by #8176