Use runReporting lint-performance

src/compiler/scala/tools/nsc/Reporting.scala

@@ -395,6 +395,7 @@ object Reporting {
     object LintRecurseWithDefault extends Lint; add(LintRecurseWithDefault)
     object LintUnitSpecialization extends Lint; add(LintUnitSpecialization)
     object LintMultiargInfix extends Lint; add(LintMultiargInfix)
+    object LintPerformance extends Lint; add(LintPerformance)
 
     sealed trait Feature extends WarningCategory { override def summaryCategory: WarningCategory = Feature }
     object Feature extends Feature { override def includes(o: WarningCategory): Boolean = o.isInstanceOf[Feature] }; add(Feature)

src/compiler/scala/tools/nsc/transform/LambdaLift.scala

@@ -18,6 +18,7 @@ import Flags._
 import scala.annotation.tailrec
 import scala.collection.mutable
 import scala.collection.mutable.{LinkedHashMap, LinkedHashSet}
+import scala.tools.nsc.Reporting.WarningCategory.LintPerformance
 
 abstract class LambdaLift extends InfoTransform {
   import global._
@@ -502,7 +503,7 @@ abstract class LambdaLift extends InfoTransform {
             }
           }
           if (settings.warnCaptured)
-            reporter.warning(tree.pos, s"Modification of variable $name within a closure causes it to be boxed.")
+            runReporting.warning(tree.pos, s"Modification of variable $name within a closure causes it to be boxed.", LintPerformance, sym)
           treeCopy.ValDef(tree, mods, name, tpt1, factoryCall)
         case ValDef(_, _, _, _) => tree
         case Return(Block(stats, value)) =>

test/files/pos/ignore-wperf.scala

@@ -0,0 +1,11 @@
+// scalac: -Werror -Wperformance -Wconf:cat=lint-performance:s
+
+class C {
+  var x = 0
+
+  def f: (Int => Int) = {
+    var y = x
+    z => y + 1
+  }
+}
+//test/files/neg/ignore-wperf.scala:7: warning: Modification of variable y within a closure causes it to be boxed.