Drop break object in scala.util

Author: odersky

compiler/test/dotty/tools/backend/jvm/LabelBytecodeTests.scala

@@ -145,7 +145,7 @@ class LabelBytecodeTests extends DottyBytecodeTest {
 
    private def checkLabelBytecodeInstructions(code: String, tpe: String)(checkOutput: List[Instruction] => Unit): Unit = {
     val source =
-      s"""import scala.util.*
+      s"""import scala.util.boundary, boundary.break
          |class Test:
          |  def test: $tpe = {
          |    ${code.linesIterator.toList.mkString("", "\n    ", "")}

library/src/scala/util/boundary.scala

@@ -11,7 +11,17 @@ package scala.util
  *      The `Break` exception class extends `RuntimeException` and is optimized so
  *      that stack trace generation is suppressed.
  *    - Better performance: breaks to enclosing scopes in the same method can
- *      be rwritten to jumps.
+ *      be rewritten to jumps.
+ *
+ * Example usage:
+ *
+ *      import scala.util.boundary, boundary.break
+ *
+ *      def firstIndex[T](xs: List[T], elem: T): Int =
+ *        boundary:
+ *          for (x, i) <- xs.zipWithIndex do
+ *            if x == elem then break(i)
+ *          -1
  */
 object boundary:
 

library/src/scala/util/break.scala

@@ -17,7 +17,7 @@ package scala.util.control
  *  performant, since returns within the scope of the same method can be
  *  rewritten by the compiler to jumps.
  */
-@deprecated("Use scala.util.boundary and scala.util.break instead", "3.3")
+@deprecated("Use scala.util.boundary instead", "3.3")
 object NonLocalReturns {
   @deprecated("Use scala.util.boundary.Break instead", "3.3")
   class ReturnThrowable[T] extends ControlThrowable {
@@ -30,12 +30,12 @@ object NonLocalReturns {
   }
 
   /** Performs a nonlocal return by throwing an exception. */
-  @deprecated("Use scala.util.break and scala.util.boundary instead", "3.3")
+  @deprecated("Use scala.util.boundary.break instead", "3.3")
   def throwReturn[T](result: T)(using returner: ReturnThrowable[? >: T]): Nothing =
     returner.throwReturn(result)
 
   /** Enable nonlocal returns in `op`. */
-  @deprecated("Use scala.util.boundary and scala.util.break instead", "3.3")
+  @deprecated("Use scala.util.boundary instead", "3.3")
   def returning[T](op: ReturnThrowable[T] ?=> T): T = {
     val returner = new ReturnThrowable[T]
     try op(using returner)

library/src/scala/util/control/NonLocalReturns.scala

@@ -1,4 +1,4 @@
-import scala.util.*
+import scala.util.boundary, boundary.break
 def test: Unit =
   boundary: label ?=>
     while true do break()

tests/pos/simple-boundary.scala

@@ -1,4 +1,4 @@
-import scala.util.*
+import scala.util.boundary, boundary.break
 
 object breakOpt:
 

tests/run/break-opt.scala

@@ -1,4 +1,4 @@
-import scala.util.*
+import scala.util.boundary, boundary.break
 import collection.mutable.ListBuffer
 
 object Test {

tests/run/breaks.scala

@@ -1,5 +1,5 @@
 package scala.util
-import boundary.Label
+import boundary.{Label, break}
 
 abstract class Result[+T, +E]
 case class Ok[+T](value: T)  extends Result[T, Nothing]

tests/run/errorhandling/Result.scala

@@ -1,4 +1,4 @@
-import scala.util.*
+import scala.util.*, boundary.break
 
 /** boundary/break as a replacement for non-local returns */
 def indexOf[T](xs: List[T], elem: T): Int =

tests/run/errorhandling/Test.scala

@@ -1,5 +1,5 @@
 package optionMockup:
-  import scala.util.{boundary, break}
+  import scala.util.boundary, boundary.break
   object optional:
     transparent inline def apply[T](inline body: boundary.Label[None.type] ?=> T): Option[T] =
       boundary(Some(body))