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Consider all arguments in Annotations.refersToParamOf #22001

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Nov 22, 2024
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Consider all arguments in Annotations.refersToParamOf #22001

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2 changes: 1 addition & 1 deletion compiler/src/dotty/tools/dotc/core/Annotations.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -73,7 +73,7 @@ object Annotations {

/** Does this annotation refer to a parameter of `tl`? */
def refersToParamOf(tl: TermLambda)(using Context): Boolean =
val args = arguments
val args = tpd.allArguments(tree)
if args.isEmpty then false
else tree.existsSubTree:
case id: (Ident | This) => id.tpe.stripped match
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When I was playing with annotations and macros, I also noticed that this check was not enough: when we write down in source code a singleton type x.type, it will be parsed as SingletonTypeTree(Ident(x)), but in a macro we usually create a reference to x.type with just a TermRef, so no Ident tree node will be involved.

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@mbovel mbovel Nov 21, 2024 •
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I actually started by writing this:

    def refersToParamOf(tl: TermLambda)(using Context): Boolean =
      tree.existsSubTree:
        _.tpe.existsPart:
          _.stripped match
            case TermParamRef(tl1, _) => tl eq tl1
            case _ => false

But couldn't come up with test-cases where that was necessary.

I didn't think of macros.

I guess we'd need something like the above if we want to handle user-generated types that don't have corresponding trees.

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When generated from a macro, wouldn't the generated type always be encapsulated in a TypeTree?

Maybe something like that would be sufficient?

    def refersToParamOf(tl: TermLambda)(using Context): Boolean =
      def referToParam(tp: Type) =
        tp.stripped match
          case TermParamRef(tl1, _) => tl eq tl1
          case _ => false
      val args = tpd.allArguments(tree)
      if args.isEmpty then false
      else tree.existsSubTree:
        case id: (Ident | This) => referToParam(id.tpe)
        case tpt: TypeTree => tpt.tpe.existsPart(referToParam)
        case _ => false

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5 changes: 5 additions & 0 deletions tests/pos/dependent-annot-type-param.scala
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@@ -0,0 +1,5 @@
class annot[T] extends annotation.Annotation
class Box[T]()
def f(x: Int): Int @annot[Box[x.type]] = x
def test =
val foo = f(42)