Annotating case class parameter annotates constructor parameter but not field

[sabenuse]

Scala3.1.2

Minimized code

case class StVo(id: Int, @(Length@field)(32) name: String)

Output

When I call getAnnotation on the name field of StVo:

Length len = namefield.getAnnotation(Length.class);

len is null.

Decompiled code:

public class StVo implements Product, Serializable {
   private final int id;
   // fixme: I need @Length(32) here 
   private final String name;

   // fixme: why is @Length(32) here?
   public StVo(final int id, @Length(32) final String name) {
      this.id = id;
      this.name = name;
   }

   // ...
}

Expectation

[noti0na1]

The logic is at PostTyper.removeUnwantedAnnotations, and documents about the meta annotations:
scala.annotation.meta.

I'm not sure about the definition of the Length annotation in the minimized code.

By default, annotations on (val-, var- or plain) constructor parameters end up on the parameter, not on any other entity.

If you want to keep the annotation at the field, you should add @field to the annotation definition.

It seems Scala 2 has the same behaviour.

[smarter]

Duplicate of #12492