Support DocDef in reflection trees

[scabug]

It would be great if reflection could add support for DocDef Nodes (scala.tools.nsc.ast.Trees#DocDef). The use case is source code generation. Being able to add doc comments would make tree based (e.g. quasi quote based) source code generation more feasible. We could use this in Slick, but it should be useful in other cases as well, like adding assisting comments when printing out trees generated by macros for visualization or debugging in the IDE.

[scabug]

Imported From: https://issues.scala-lang.org/browse/SI-7993?orig=1
Reporter: @cvogt
Affected Versions: 2.11.0-M7
Blocks #6267, #8904

[scabug]

@cvogt said:
We decided on using an annotation instead and letting the pretty printer use that to generate comments. Adding DocDef nodes would easily get in the way of existing tree processors.

[scabug]

@szeiger said:
@xeno-by, can this issue be closed or is the original request still on the table?

[SethTisue]

anyone know the status on this? I feel like this came up recently, but can't remember where/why.

[harpocrates]

The situation is actually a little more dire than just not being able to create methods with docstrings: it is impossible to match on a DocDef too. Consider the simple macro in this StackOverflow question. The quasiquote pattern matching is idiomatic yet it will fail with sbt doc (but not sbt compile).

My particular use case is fixing shadaj/slinky#380 (which I'm fairly certain is the same issue).

Even if the full power of DocDef stays hidden, it seems pretty important to be able to unwrap doc'ed trees to get their undoc'ed variants (which can be pattern matched with quasiquotes).

[lauraaraviciute]

Hi guys, is there any update on this?
I think on a project I have come up with the same problem. We are working with scalaz and are using the following conventions:

  type OurState[T] = State[X, T]

  def doSomething(...): OurState[Unit] = {
    (for {
      x <- get[X].liftM[OptionT]

And are getting errors when generating scaladoc:

* What went wrong:
Execution failed for task ':paygrid-core:scaladoc'.
> Document failed because of an internal documenter error (Document failed with 3 errors; see the documenter error output for details.); see the error output for details.
[ant:scaladoc]..: error: value liftM is not a member of scalaz.State[com..state.X,...com..state.X]
[ant:scaladoc]         x <- get[X].liftM[OptionT]

[SethTisue]

@lauraaraviciute Nobody is working on this, to my knowledge.

But it isn't obvious to me from the error message you've included whether it's actually the same problem.

[lauraaraviciute]

I believe my problem is similar to that of the https://stackoverflow.com/questions/42684101/scaladoc-generation-fails-when-referencing-methods-generated-by-annotation-macro