Treat java / scala deprecated annotations more uniformly

[scabug]

There seem to be a some of inconsistencies in the way we deprecation annotations.

• Should the scala @deprecated add the Java annotation @Deprecated, or just the ACC_DEPRECATED flag?
• Adding Java's @Deprecated to a Scala class does not trigger any deprecation warnings (neither in scalac nor in javac)

etc.

[scabug]

Imported From: https://issues.scala-lang.org/browse/SI-8883?orig=1
Reporter: @lrytz
Affected Versions: 2.11.2

[scabug]

@soc said (edited on Oct 7, 2014 3:08:42 PM UTC):
As far as I see, @Deprecated being added to the RuntimeVisibleAttribute is just because it is defined with RetentionPolicy RUNTIME, but ACC_DEPRECATED is the only thing that counts semantically.

From the declaration of @deprecated it is just a "source annotation". I wouldn't bother introducing another special case, especially because the attribute really just records whether "annotation X was here" and doesn't carry any semantic meaning.

If we want @deprecated to show up, we should make it extend the appropriate Annotation type in Scala.

Whether we'd like to support @Deprecated is an interesting question.

By the way, maybe we can just type alias @Deprecated to @deprecated in Scala? That might be a much simpler approach.

[dwijnand]

scala/scala#8781