Fix parsing Java annotation values

[noti0na1]

The annotation arguments were not parsed correctly; since the literal LiteralT returns was always the annotaion id string.

[noti0na1]

@smarter It there a way to test the annotation values read by the compiler?

[smarter]

You could write a macro that calls getAnnotation

[odersky]

The changes to the parser look OK to me, but it would be nice to have a test.

[noti0na1]

@smarter @odersky It is tricky to write a test to checking the values of annotations in the compiler.
I don't know how to write a macro which calls the getAnnotation function in the compiler.

[smarter]

I don't know how to write a macro which calls the getAnnotation function in the compiler.

getAnnotation is available in the library as part of tasty-reflect, /cc @nicolasstucki could you help @noti0na1 come up with a testcase?

[nicolasstucki]

@noti0na1 What was the code where you saw that? Which annotation was it?

[noti0na1]

@nicolasstucki Some of my code break the typing of annotations in Java. During debugging, I noticed the arguments from all annotations (in Java file) are not parsed correctly.

If you print out the tree, you may see the wrong arguments?

[dwijnand]

@noti0na1 could you provide a code example showing what happened and what you expected. That would form the basis for writing a test case for this - it's a little hard to understand by reverse engineering your patch here.

[SethTisue]

Does this affect runtime annotations as well as compile-time-only annotations? A runtime annotation might be easier to construct a test case around.

[smarter]

@SethTisue this PR changes the JavaParser so it affects how the scala compiler (and therefore macros) sees Java annotations coming from .java file, but it has no impact on what annotations are kept at runtime.

[noti0na1]

@dwijnand

An example would be any Java class with some annotations:

class Test {
  @SuppressWarnings("unchecked")
  void f() {}
}

I found this bug because I was trying to print some trees in the compiler, and I noticed the parsed arguments were wrong.

The compiler doesn't use the annotation arguments in Java files currently, so it is difficult to write a test.
We can use a macro to show the annotations, but I don't know how to do it.

[anatoliykmetyuk]

@noti0na1 here's a macro that will give you annotations of the first method of stuff.Bar class:

mcr.scala

package stuff

import scala.quoted.*

inline def mcr: Any = ${ mcrImpl }
def mcrImpl(using Quotes): Expr[Any] =
  import quotes.reflect.*
  println(Symbol.requiredClass("stuff.Bar").declaredMethods.head.annotations)
  val tree = '{()}
  tree

Test.scala

package stuff

trait Bar:
  @SuppressWarnings(Array("unchecked"))
  def f(x: Int) = ???

@main def Test = mcr

It successfully obtains annotations for types from the Scala sources. However, for a class coming from a Java source, it doesn't find any annotations. Maybe you can come up with something based on the example above.

[noti0na1]

I add a test using the macro created by @anatoliykmetyuk , we can see from the output the arguments are correctly parsed now ("a", "b", "c" and "d").

@smarter Could you review the PR again? Thanks.