Upgrade to scala-asm 6.2

See: scala/scala-asm#5

Upstream changes in ASM:

  scala/scala-asm@ASM_6_0...ASM_6_2
  http://asm.ow2.io/versions.html

The motivations, other than just keeping current, are:

  - support for Java 9/10/11 updates to the classfile format.
  - reducing needless String => Array[Char] conversions thanks
    to internal changes in ASM.

This PR will fail to build until we publish artifact
from scala/scala-asm.

Author: retronym

src/compiler/scala/tools/asm/LabelAccess.java

@@ -761,6 +761,8 @@ abstract class BTypes {
             // finds the first common one.
             // MOST LIKELY the answer can be found here, see the comments and links by Miguel:
             //  - https://github.com/scala/bug/issues/3872
+            // @jz Wouldn't it be better to walk the superclass chain of both types in reverse (starting from Object), and
+            //     finding the last common link? That would be O(N), whereas this looks O(N^2)
             firstCommonSuffix(this :: this.superClassesTransitive.orThrow, other :: other.superClassesTransitive.orThrow)
         }
 

src/compiler/scala/tools/nsc/backend/jvm/BTypes.scala

@@ -13,7 +13,7 @@ import scala.tools.asm
 import scala.tools.asm.Opcodes._
 import scala.tools.asm.tree._
 import scala.tools.asm.tree.analysis._
-import scala.tools.asm.{Handle, Label, LabelAccess, Type}
+import scala.tools.asm.{Handle, Label, Type}
 import scala.tools.nsc.backend.jvm.BTypes._
 import scala.tools.nsc.backend.jvm.GenBCode._
 import scala.tools.nsc.backend.jvm.analysis.BackendUtils._
@@ -591,9 +591,18 @@ object BackendUtils {
   def clearDceDone(method: MethodNode) = method.access &= ~ACC_DCE_DONE
 
   private val LABEL_REACHABLE_STATUS = 0x1000000
-  def isLabelReachable(label: LabelNode) = LabelAccess.isLabelFlagSet(label.getLabel, LABEL_REACHABLE_STATUS)
-  def setLabelReachable(label: LabelNode) = LabelAccess.setLabelFlag(label.getLabel, LABEL_REACHABLE_STATUS)
-  def clearLabelReachable(label: LabelNode) = LabelAccess.clearLabelFlag(label.getLabel, LABEL_REACHABLE_STATUS)
+  private def isLabelFlagSet(l: Label, f: Int): Boolean = (l.flags & f) != 0
+
+  private def setLabelFlag(l: Label, f: Int): Unit = {
+    l.flags |= f
+  }
+
+  private def clearLabelFlag(l: Label, f: Int): Unit = {
+    l.flags &= ~f
+  }
+  def isLabelReachable(label: LabelNode) = isLabelFlagSet(label.getLabel, LABEL_REACHABLE_STATUS)
+  def setLabelReachable(label: LabelNode) = setLabelFlag(label.getLabel, LABEL_REACHABLE_STATUS)
+  def clearLabelReachable(label: LabelNode) = clearLabelFlag(label.getLabel, LABEL_REACHABLE_STATUS)
 
   abstract class NestedClassesCollector[T] extends GenericSignatureVisitor {
     val innerClasses = mutable.Set.empty[T]

src/compiler/scala/tools/nsc/backend/jvm/analysis/BackendUtils.scala

@@ -457,7 +457,7 @@ case class ParameterProducer(local: Int)
 case class UninitializedLocalProducer(local: Int)                                         extends InitialProducer
 case class ExceptionProducer[V <: Value](handlerLabel: LabelNode, handlerFrame: Frame[V]) extends InitialProducer
 
-class InitialProducerSourceInterpreter extends SourceInterpreter {
+class InitialProducerSourceInterpreter extends SourceInterpreter(scala.tools.asm.Opcodes.ASM7_EXPERIMENTAL) {
   override def newParameterValue(isInstanceMethod: Boolean, local: Int, tp: Type): SourceValue = {
     new SourceValue(tp.getSize, ParameterProducer(local))
   }

src/compiler/scala/tools/nsc/backend/jvm/analysis/ProdConsAnalyzerImpl.scala

@@ -5,7 +5,7 @@ package analysis
 import scala.tools.asm.Type
 import scala.tools.asm.tree.analysis.{BasicValue, BasicInterpreter}
 
-abstract class TypeFlowInterpreter extends BasicInterpreter {
+abstract class TypeFlowInterpreter extends BasicInterpreter(scala.tools.asm.Opcodes.ASM7_EXPERIMENTAL) {
   override def newValue(tp: Type) = {
     if (tp == null) super.newValue(tp)
     else if (isRef(tp)) new BasicValue(tp)

src/compiler/scala/tools/nsc/backend/jvm/analysis/TypeFlowInterpreter.scala

@@ -7,5 +7,5 @@ starr.version=2.13.0-M4
 # Other usages:
 #  - scala-asm: jar content included in scala-compiler
 #  - jline: shaded with JarJar and included in scala-compiler
-scala-asm.version=6.0.0-scala-1
+scala-asm.version=6.2.0-scala-2
 jline.version=2.14.6