Add since annotation

Author: Kordyjan

compiler/src/dotty/tools/dotc/core/Definitions.scala

@@ -948,6 +948,7 @@ class Definitions {
   @tu lazy val FunctionalInterfaceAnnot: ClassSymbol = requiredClass("java.lang.FunctionalInterface")
   @tu lazy val TargetNameAnnot: ClassSymbol = requiredClass("scala.annotation.targetName")
   @tu lazy val VarargsAnnot: ClassSymbol = requiredClass("scala.annotation.varargs")
+  @tu lazy val SinceAnnot: ClassSymbol = requiredClass("scala.annotation.since")
 
   @tu lazy val JavaRepeatableAnnot: ClassSymbol = requiredClass("java.lang.annotation.Repeatable")
 

compiler/src/dotty/tools/dotc/typer/RefChecks.scala

@@ -911,6 +911,7 @@ object RefChecks {
   private def checkUndesiredProperties(sym: Symbol, pos: SrcPos)(using Context): Unit =
     checkDeprecated(sym, pos)
     checkExperimental(sym, pos)
+    checkSinceAnnot(sym, pos)
 
     val xMigrationValue = ctx.settings.Xmigration.value
     if xMigrationValue != NoScalaVersion then
@@ -970,6 +971,21 @@ object RefChecks {
       for annot <- sym.annotations if annot.symbol.isExperimental do
         Feature.checkExperimentalDef(annot.symbol, annot.tree)
 
+  private def checkSinceAnnot(sym: Symbol, pos: SrcPos)(using Context): Unit =
+    for
+      annot <- sym.getAnnotation(defn.SinceAnnot)
+      version <- annot.argumentConstantString(0)
+    do
+      val releaseVersion = ctx.settings.scalaRelease.value
+      ScalaVersion.parse(version) match
+        case Success(symVersion) if symVersion > ctx.settings.scalaRelease.value =>
+          report.error(
+            i"$sym was added in Scala $version, therefore it cannot be used in the code targeting Scala ${releaseVersion.unparse}",
+            pos)
+        case Failure(ex) =>
+          report.warning(i"$sym has an unparsable version number: ${ex.getMessage}", pos)
+        case _ =>
+
   /** If @migration is present (indicating that the symbol has changed semantics between versions),
    *  emit a warning.
    */

library/src/scala/annotation/since.scala

@@ -0,0 +1,4 @@
+package scala.annotation
+
+/** An annotation that is used to mark symbols added to the stdlib after 3.0 release */
+class since(scalaRelease: String) extends scala.annotation.StaticAnnotation

library/src/scala/quoted/Quotes.scala

@@ -1,6 +1,6 @@
 package scala.quoted
 
-import scala.annotation.experimental
+import scala.annotation.{ experimental, since }
 import scala.reflect.TypeTest
 
 /** Current Quotes in scope
@@ -3704,6 +3704,7 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>
         def memberField(name: String): Symbol
 
         /** Get named non-private fields declared or inherited */
+        @since("3.1")
         def fieldMember(name: String): Symbol
 
         /** Get all non-private fields declared or inherited */

tests/neg/since/since_t3.0.scala

@@ -0,0 +1,6 @@
+import scala.quoted.*
+
+def useQuotes(using Quotes) =
+  import quotes.reflect.*
+  def useFieldMember(s: Symbol) = s.fieldMember("abc") // error
+  useFieldMember