Build library under -Xsource:3 [ci: last-only]

build.sbt

@@ -413,7 +413,9 @@ lazy val library = configureAsSubproject(project)
     name := "scala-library",
     description := "Scala Standard Library",
     Compile / scalacOptions ++= Seq("-sourcepath", (Compile / scalaSource).value.toString),
-    Compile / scalacOptions ++= Seq("-Xlint", "-feature"),
+    Compile / scalacOptions ++= Seq("-Xlint", "-feature", "-Xsource:3"),
+    Compile / scalacOptions ++= Seq("-Wconf:cat=scala3-migration&msg=elidable&site=scala.Predef:s"),
+    Compile / scalacOptions ++= Seq("-Wconf:cat=scala3-migration&msg=constructor modifiers&site=scala.concurrent.duration.Deadline:s"), // for bootstrap until restarr
     Compile / doc / scalacOptions ++= {
       val libraryAuxDir = (ThisBuild / baseDirectory).value / "src/library-aux"
       Seq(

src/compiler/scala/tools/nsc/typechecker/Typers.scala

@@ -3303,7 +3303,7 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
     def typedStats(stats: List[Tree], exprOwner: Symbol): List[Tree] = {
       val inBlock = exprOwner == context.owner
       def includesTargetPos(tree: Tree) =
-        tree.pos.isRange && context.unit.exists && (tree.pos includes context.unit.targetPos)
+        tree.pos.isRange && context.unit.exists && tree.pos.includes(context.unit.targetPos)
       val localTarget = stats exists includesTargetPos
       def typedStat(stat: Tree): Tree = stat match {
         case s if context.owner.isRefinementClass && !treeInfo.isDeclarationOrTypeDef(s) => OnlyDeclarationsError(s)
@@ -3418,8 +3418,16 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
             // OPT: shouldAdd is usually true. Call it here, rather than in the outer loop
             case Some(tree) if shouldAdd(sym) =>
               // if the completer set the IS_ERROR flag, retract the stat (currently only used by applyUnapplyMethodCompleter)
-              if (!sym.initialize.hasFlag(IS_ERROR))
-                newStats += typedStat(tree) // might add even more synthetics to the scope
+              if (!sym.initialize.hasFlag(IS_ERROR)) {
+                val newStat = typedStat(tree)
+                if (currentRun.isScala3 && !sym.owner.isCaseClass)
+                  tree match {
+                    case DefDef(mods, nme.apply, _, _, _, _) if mods.hasFlag(PRIVATE) || mods.privateWithin != tpnme.EMPTY =>
+                      runReporting.warning(tree.pos, "access modifiers for `apply` method are copied from the case class constructor", WarningCategory.Scala3Migration, sym)
+                    case _ =>
+                  }
+                newStats += newStat // might add even more synthetics to the scope
+              }
               context.unit.synthetics -= sym
             case _ => ()
           }

src/compiler/scala/tools/nsc/typechecker/Unapplies.scala

@@ -156,10 +156,6 @@ trait Unapplies extends ast.TreeDSL {
     val mods =
       if (applyShouldInheritAccess(inheritedMods))
         (caseMods | (inheritedMods.flags & PRIVATE)).copy(privateWithin = inheritedMods.privateWithin)
-          .tap { mods =>
-            if (currentRun.isScala3 && mods != caseMods)
-              runReporting.warning(cdef.pos, "constructor modifiers are assumed by synthetic `apply` method", WarningCategory.Scala3Migration, cdef.symbol)
-          }
       else
         caseMods
     factoryMeth(mods, nme.apply, cdef)
@@ -282,7 +278,7 @@ trait Unapplies extends ast.TreeDSL {
           Modifiers(SYNTHETIC | (inheritedMods.flags & AccessFlags), inheritedMods.privateWithin)
             .tap { mods =>
               if (currentRun.isScala3 && mods != Modifiers(SYNTHETIC))
-                runReporting.warning(cdef.pos, "constructor modifiers are assumed by synthetic `copy` method", WarningCategory.Scala3Migration, cdef.symbol)
+                runReporting.warning(cdef.pos, "access modifiers for `copy` method are copied from the case class constructor", WarningCategory.Scala3Migration, cdef.symbol)
             }
         }
         else Modifiers(SYNTHETIC)

src/library/scala/collection/Iterator.scala

@@ -969,8 +969,8 @@ trait Iterator[+A] extends IterableOnce[A] with IterableOnceOps[A, Iterator, Ite
 object Iterator extends IterableFactory[Iterator] {
 
   private[this] val _empty: Iterator[Nothing] = new AbstractIterator[Nothing] {
-    def hasNext = false
-    def next() = throw new NoSuchElementException("next on empty iterator")
+    override def hasNext: Boolean = false
+    override def next(): Nothing = throw new NoSuchElementException("next on empty iterator")
     override def knownSize: Int = 0
     override protected def sliceIterator(from: Int, until: Int): AbstractIterator[Nothing] = this
   }

src/library/scala/collection/immutable/HashMap.scala

@@ -2381,7 +2381,7 @@ private[immutable] final class HashMapBuilder[K, V] extends ReusableBuilder[(K,
             currentValueCursor += 1
           }
 
-          override def next() = Iterator.empty.next()
+          override def next(): (K, V) = Iterator.empty.next()
         }
       case hm: collection.mutable.HashMap[K, V] =>
         val iter = hm.nodeIterator

src/library/scala/collection/immutable/HashSet.scala

@@ -2097,7 +2097,7 @@ private[collection] final class HashSetBuilder[A] extends ReusableBuilder[A, Has
             )
             currentValueCursor += 1
           }
-          override def next() = Iterator.empty.next()
+          override def next(): A = Iterator.empty.next()
         }
       case other =>
         val it = other.iterator

src/library/scala/concurrent/duration/Deadline.scala

@@ -12,29 +12,33 @@
 
 package scala.concurrent.duration
 
-/**
- * This class stores a deadline, as obtained via `Deadline.now` or the
- * duration DSL:
+import annotation.nowarn
+
+/** A deadline, as a duration of time remaining, calculated from the present.
+ *
+ *  Deadlines are obtained via `Deadline.now` or the duration DSL:
  *
- * {{{
- * import scala.concurrent.duration._
- * 3.seconds.fromNow
- * }}}
+ *  {{{
+ *  import scala.concurrent.duration._
+ *  3.seconds.fromNow
+ *  }}}
  *
- * Its main purpose is to manage repeated attempts to achieve something (like
- * awaiting a condition) by offering the methods `hasTimeLeft` and `timeLeft`.  All
- * durations are measured according to `System.nanoTime`; this
- * does not take into account changes to the system clock (such as leap
- * seconds).
+ *  The purpose of a deadline is to support managed repeated attempts,
+ *  such as when awaiting a condition, by offering the methods `hasTimeLeft` and `timeLeft`.
+ *
+ *  All durations are measured according to `System.nanoTime`;
+ *  this does not take into account changes to the system clock, such as leap seconds.
  */
 case class Deadline private (time: FiniteDuration) extends Ordered[Deadline] {
   /**
    * Return a deadline advanced (i.e., moved into the future) by the given duration.
    */
+  @nowarn("cat=deprecation")
   def +(other: FiniteDuration): Deadline = copy(time = time + other)
   /**
    * Return a deadline moved backwards (i.e., towards the past) by the given duration.
    */
+  @nowarn("cat=deprecation")
   def -(other: FiniteDuration): Deadline = copy(time = time - other)
   /**
    * Calculate time difference between this and the other deadline, where the result is directed (i.e., may be negative).
@@ -65,6 +69,10 @@ case class Deadline private (time: FiniteDuration) extends Ordered[Deadline] {
    * The natural ordering for deadline is determined by the natural order of the underlying (finite) duration.
    */
   def compare(other: Deadline): Int = time compare other.time
+
+  // expose public copy for backward compatibility under -Xsource:3
+  @deprecated("use now or FiniteDuration#fromNow", since="2.13.13")
+  def copy(time: FiniteDuration = this.time): Deadline = Deadline(time)
 }
 
 object Deadline {
@@ -73,6 +81,7 @@ object Deadline {
    * advancing it to obtain a future deadline, or for sampling the current time exactly once and
    * then comparing it to multiple deadlines (using subtraction).
    */
+  @nowarn("cat=deprecation")
   def now: Deadline = Deadline(Duration(System.nanoTime, NANOSECONDS))
 
   /**
@@ -82,4 +91,7 @@ object Deadline {
     def compare(a: Deadline, b: Deadline): Int = a compare b
   }
 
+  // expose public apply for backward compatibility under -Xsource:3
+  @deprecated("use now or FiniteDuration#fromNow", since="2.13.13")
+  def apply(time: FiniteDuration): Deadline = new Deadline(time)
 }

test/files/neg/t12798-migration.check

@@ -38,16 +38,16 @@ t12798-migration.scala:17: warning: Unicode escapes in raw interpolations are ig
 t12798-migration.scala:18: warning: Unicode escapes in raw interpolations are ignored under -Xsource:3; use literal characters instead
   def g = raw"""\u0043 is for Cat"""
                 ^
-t12798-migration.scala:50: warning: constructor modifiers are assumed by synthetic `copy` method
+t12798-migration.scala:50: warning: access modifiers for `copy` method are copied from the case class constructor
 case class `case mods propagate` private (s: String)
            ^
 t12798-migration.scala:60: warning: under -Xsource:3, inferred Option[Int] instead of Some[Int] [quickfixable]
   override def f = Some(27)
                ^
-t12798-migration.scala:50: warning: constructor modifiers are assumed by synthetic `apply` method
+t12798-migration.scala:50: warning: access modifiers for `apply` method are copied from the case class constructor
 case class `case mods propagate` private (s: String)
            ^
-t12798-migration.scala:52: warning: constructor modifiers are assumed by synthetic `apply` method
+t12798-migration.scala:52: warning: access modifiers for `apply` method are copied from the case class constructor
 case class `copyless case mods propagate` private (s: String) {
            ^
 15 warnings

test/files/neg/t12798.check

@@ -60,7 +60,7 @@ Scala 3 migration messages are errors under -Xsource:3. Use -Wconf / @nowarn to
 Applicable -Wconf / @nowarn filters for this fatal warning: msg=<part of the message>, cat=scala3-migration, site=interpolated unicode such as C.g
   def g = raw"""\u0043 is for Cat"""
                 ^
-t12798.scala:50: error: constructor modifiers are assumed by synthetic `copy` method
+t12798.scala:50: error: access modifiers for `copy` method are copied from the case class constructor
 Scala 3 migration messages are errors under -Xsource:3. Use -Wconf / @nowarn to filter them or add -Xmigration to demote them to warnings.
 Applicable -Wconf / @nowarn filters for this fatal warning: msg=<part of the message>, cat=scala3-migration, site=case mods propagate
 case class `case mods propagate` private (s: String)
@@ -70,9 +70,9 @@ Scala 3 migration messages are errors under -Xsource:3. Use -Wconf / @nowarn to
 Applicable -Wconf / @nowarn filters for this fatal warning: msg=<part of the message>, cat=scala3-migration, site=Child.f
   override def f = Some(27)
                ^
-t12798.scala:52: error: constructor modifiers are assumed by synthetic `apply` method
+t12798.scala:52: error: access modifiers for `apply` method are copied from the case class constructor
 Scala 3 migration messages are errors under -Xsource:3. Use -Wconf / @nowarn to filter them or add -Xmigration to demote them to warnings.
-Applicable -Wconf / @nowarn filters for this fatal warning: msg=<part of the message>, cat=scala3-migration, site=copyless case mods propagate
+Applicable -Wconf / @nowarn filters for this fatal warning: msg=<part of the message>, cat=scala3-migration, site=copyless case mods propagate.apply
 case class `copyless case mods propagate` private (s: String) {
            ^
 15 errors