Merge pull request scala#10401 from SethTisue/merge-2.12-to-2.13-20230517

Author: SethTisue

project/build.properties

@@ -1 +1 @@
-sbt.version=1.8.2
+sbt.version=1.8.3

project/plugins.sbt

@@ -17,7 +17,7 @@ buildInfoKeys := Seq[BuildInfoKey](buildClasspath)
 
 buildInfoPackage := "scalabuild"
 
-addSbtPlugin("com.typesafe" % "sbt-mima-plugin" % "1.1.1")
+addSbtPlugin("com.typesafe" % "sbt-mima-plugin" % "1.1.2")
 
 libraryDependencies ++= Seq(
   "org.eclipse.jgit" % "org.eclipse.jgit" % "4.11.9.201909030838-r",

src/compiler/scala/tools/nsc/symtab/classfile/ClassfileParser.scala

@@ -840,7 +840,10 @@ abstract class ClassfileParser(reader: ReusableInstance[ReusableDataReader]) {
             val paramNameAccess = new Array[Int](paramCount)
             var i = 0
             while (i < paramCount) {
-              paramNames(i) = pool.getExternalName(u2())
+              paramNames(i) = u2() match {
+                case 0 => null  // may occur on JDK 21+, as per scala/bug#12783
+                case index => pool.getExternalName(index)
+              }
               paramNameAccess(i) = u2()
               i += 1
             }
@@ -1358,6 +1361,7 @@ abstract class ClassfileParser(reader: ReusableInstance[ReusableDataReader]) {
       sym setInfo createFromClonedSymbols(alias.initialize.typeParams, alias.tpe)(typeFun)
     }
   }
+  // on JDK 21+, `names` may include nulls, as per scala/bug#12783
   private class ParamNames(val names: Array[NameOrString], val access: Array[Int]) {
     assert(names.length == access.length, "Require as many names as access")
     def length = names.length
@@ -1462,8 +1466,10 @@ abstract class ClassfileParser(reader: ReusableInstance[ReusableDataReader]) {
             case (i, param) =>
               val isSynthetic = (paramNames.access(i) & ACC_SYNTHETIC) != 0
               if (!isSynthetic) {
-                param.name = paramNames.names(i).name.toTermName.encode
                 param.resetFlag(SYNTHETIC)
+                val nameOrString = paramNames.names(i)
+                if (nameOrString != null)
+                  param.name = nameOrString.name.toTermName.encode
               }
           }
           // there's not anything we can do, but it's slightly worrisome

src/partest/scala/tools/partest/ReplTest.scala

@@ -75,7 +75,7 @@ trait Lambdaless extends ReplTest {
   override def normalize(s: String) = stripLambdaClassName(super.normalize(s))
 }
 object Lambdaless {
-  private val lambdaless = """\$Lambda\$\d+/(?:0x[a-f0-9]{16}|\d+)(@[a-fA-F0-9]+)?""".r
+  private val lambdaless = """\$Lambda(?:\$\d+)?/(?:0x[a-f0-9]{16}|\d+)(?:@[a-fA-F0-9]+)?""".r
   private def stripLambdaClassName(s: String): String = lambdaless.replaceAllIn(s, Regex.quoteReplacement("<function>"))
 }
 

test/files/run/sammy_after_implicit_view.scala

@@ -3,7 +3,7 @@ trait MySam { def apply(x: Int): String }
 // check that SAM conversion happens after implicit view application
 object Test extends App {
   final val AnonFunClass = "$anon$"
-  final val LMFClass = "$$Lambda$" // LambdaMetaFactory names classes like this
+  final val LMFClass = "$$Lambda" // LambdaMetaFactory names classes like this
 
   //  if there's an implicit conversion, it does not takes precedence (because that's what dotty does)
   def implicitSam() = {

test/files/run/sammy_restrictions_LMF.scala

@@ -15,7 +15,7 @@ trait TClassParent extends B { def apply(x: Int): String }
 
 object Test extends App {
   final val AnonFunClass = "$anonfun$"
-  final val LMFClass = "$$Lambda$" // LambdaMetaFactory names classes like this
+  final val LMFClass = "$$Lambda" // LambdaMetaFactory names classes like this
 
   private def LMF(f: Any): Unit = {
     val className = f.getClass.toString