Gradual warning for deprecated nonlocal return

Author: som-snytt

compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala

@@ -262,9 +262,9 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
       case tp: ClassInfo =>
         if tp.cls.derivesFrom(defn.PolyFunctionClass) then
           tp.member(nme.apply).info match
-            case info: PolyType => return toTextMethodAsFunction(info)
-            case _ =>
-        toTextParents(tp.parents) ~~ "{...}"
+            case info: PolyType => toTextMethodAsFunction(info)
+            case _ => toTextParents(tp.parents) ~~ "{...}"
+        else toTextParents(tp.parents) ~~ "{...}"
       case JavaArrayType(elemtp) =>
         toText(elemtp) ~ "[]"
       case tp: LazyRef if !printDebug =>

compiler/src/dotty/tools/dotc/transform/NonLocalReturns.scala

@@ -5,7 +5,7 @@ import core._
 import Contexts._, Symbols._, Types._, Flags._, StdNames._
 import MegaPhase._
 import NameKinds.NonLocalReturnKeyName
-import config.SourceVersion._
+import config.SourceVersion.*
 
 object NonLocalReturns {
   import ast.tpd._
@@ -95,10 +95,11 @@ class NonLocalReturns extends MiniPhase {
 
   override def transformReturn(tree: Return)(using Context): Tree =
     if isNonLocalReturn(tree) then
-      report.errorOrMigrationWarning(
+      report.gradualErrorOrMigrationWarning(
           "Non local returns are no longer supported; use scala.util.control.NonLocalReturns instead",
           tree.srcPos,
-          from = future)
+          warnFrom = `3.0`,
+          errorFrom = future)
       nonLocalReturnThrow(tree.expr, tree.from.symbol).withSpan(tree.span)
     else tree
 }

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

@@ -4,7 +4,7 @@ package scala.util.control
  *
  *  Usage:
  *
- *     import scala.util.control.NonLocalReturns._
+ *     import scala.util.control.NonLocalReturns.*
  *
  *     returning { ... throwReturn(x) ... }
  */