Remove some unsafe nulls (#23309)

noti0na1 · web-flow · commit 0be20913a400 · 2025-06-03T19:23:26.000+02:00
Remove some more unsafe nulls.
diff --git a/compiler/src/dotty/tools/backend/jvm/BCodeAsmCommon.scala b/compiler/src/dotty/tools/backend/jvm/BCodeAsmCommon.scala
@@ -2,8 +2,6 @@ package dotty.tools
 package backend
 package jvm
 
-import scala.language.unsafeNulls
-
 import dotty.tools.dotc.core.Flags.*
 import dotty.tools.dotc.core.Symbols.*
 import dotty.tools.dotc.report
@@ -79,7 +77,7 @@ final class BCodeAsmCommon[I <: DottyBackendInterface](val interface: I) {
     enclosingClass(classSym.originalOwner.originalLexicallyEnclosingClass)
   }
 
-  /*final*/ case class EnclosingMethodEntry(owner: String, name: String, methodDescriptor: String)
+  /*final*/ case class EnclosingMethodEntry(owner: String, name: String | Null, methodDescriptor: String | Null)
 
   /**
    * Data for emitting an EnclosingMethod attribute. None if `classSym` is a member class (not
diff --git a/compiler/src/dotty/tools/backend/jvm/BackendUtils.scala b/compiler/src/dotty/tools/backend/jvm/BackendUtils.scala
@@ -8,7 +8,6 @@ import scala.collection.mutable
 import scala.jdk.CollectionConverters.*
 import dotty.tools.dotc.report
 
-import scala.language.unsafeNulls
 
 /**
  * This component hosts tools and utilities used in the backend that require access to a `BTypes`
diff --git a/compiler/src/dotty/tools/backend/jvm/CodeGen.scala b/compiler/src/dotty/tools/backend/jvm/CodeGen.scala
@@ -1,6 +1,5 @@
 package dotty.tools.backend.jvm
 
-import scala.language.unsafeNulls
 
 import dotty.tools.dotc.CompilationUnit
 import dotty.tools.dotc.ast.Trees.{PackageDef, ValDef}
@@ -71,7 +70,7 @@ class CodeGen(val int: DottyBackendInterface, val primitives: DottyPrimitives)(
           val tastyAttrNode = if (mirrorClassNode ne null) mirrorClassNode else mainClassNode
           genTastyAndSetAttributes(sym, tastyAttrNode)
 
-        def registerGeneratedClass(classNode: ClassNode, isArtifact: Boolean): Unit =
+        def registerGeneratedClass(classNode: ClassNode | Null, isArtifact: Boolean): Unit =
           if classNode ne null then
             generatedClasses += GeneratedClass(classNode,
               sourceClassName = sym.javaClassName,
@@ -131,7 +130,7 @@ class CodeGen(val int: DottyBackendInterface, val primitives: DottyPrimitives)(
     }
     clsFile => {
       val className = cls.name.replace('/', '.')
-      if (ctx.compilerCallback != null)
+      if (ctx.compilerCallback ne null)
         ctx.compilerCallback.onClassGenerated(sourceFile, convertAbstractFile(clsFile), className)
 
       ctx.withIncCallback: cb =>
diff --git a/compiler/src/dotty/tools/backend/jvm/DottyBackendInterface.scala b/compiler/src/dotty/tools/backend/jvm/DottyBackendInterface.scala
@@ -1,6 +1,5 @@
 package dotty.tools.backend.jvm
 
-import scala.language.unsafeNulls
 
 import dotty.tools.dotc.ast.tpd
 import dotty.tools.dotc.core.Flags.*
@@ -44,14 +43,14 @@ class DottyBackendInterface(val superCallsMap: ReadOnlyMap[Symbol, List[ClassSym
 
   object DesugaredSelect extends DeconstructorCommon[tpd.Tree] {
 
-    var desugared: tpd.Select = null
+    var desugared: tpd.Select | Null = null
 
     override def isEmpty: Boolean =
       desugared eq null
 
-    def _1: Tree =  desugared.qualifier
+    def _1: Tree =  desugared.nn.qualifier
 
-    def _2: Name = desugared.name
+    def _2: Name = desugared.nn.name
 
     override def unapply(s: tpd.Tree): this.type = {
       s match {
@@ -69,17 +68,17 @@ class DottyBackendInterface(val superCallsMap: ReadOnlyMap[Symbol, List[ClassSym
   }
 
   object ArrayValue extends DeconstructorCommon[tpd.JavaSeqLiteral] {
-    def _1: Type = field.tpe match {
+    def _1: Type = field.nn.tpe match {
       case JavaArrayType(elem) => elem
       case _ =>
-        report.error(em"JavaSeqArray with type ${field.tpe} reached backend: $field", ctx.source.atSpan(field.span))
+        report.error(em"JavaSeqArray with type ${field.nn.tpe} reached backend: $field", ctx.source.atSpan(field.nn.span))
         UnspecifiedErrorType
     }
-    def _2: List[Tree] = field.elems
+    def _2: List[Tree] = field.nn.elems
   }
 
-  abstract class DeconstructorCommon[T >: Null <: AnyRef] {
-    var field: T = null
+  abstract class DeconstructorCommon[T <: AnyRef] {
+    var field: T | Null = null
     def get: this.type = this
     def isEmpty: Boolean = field eq null
     def isDefined = !isEmpty
diff --git a/compiler/src/dotty/tools/backend/jvm/GeneratedClassHandler.scala b/compiler/src/dotty/tools/backend/jvm/GeneratedClassHandler.scala
@@ -14,7 +14,6 @@ import scala.util.control.NonFatal
 import dotty.tools.dotc.core.Phases
 import dotty.tools.dotc.core.Decorators.em
 
-import scala.language.unsafeNulls
 import scala.compiletime.uninitialized
 
 /**
@@ -189,4 +188,4 @@ final private class CompilationUnitInPostProcess(private var classes: List[Gener
   var task: Future[Unit] = uninitialized
 
   val bufferedReporting = new PostProcessorFrontendAccess.BufferingBackendReporting()
-}
+}
diff --git a/compiler/src/dotty/tools/dotc/classpath/ZipArchiveFileLookup.scala b/compiler/src/dotty/tools/dotc/classpath/ZipArchiveFileLookup.scala
@@ -3,7 +3,6 @@
  */
 package dotty.tools.dotc.classpath
 
-import scala.language.unsafeNulls
 
 import java.io.File
 import java.net.URL
@@ -21,7 +20,7 @@ trait ZipArchiveFileLookup[FileEntryType <: ClassRepresentation] extends Efficie
   val zipFile: File
   def release: Option[String]
 
-  assert(zipFile != null, "Zip file in ZipArchiveFileLookup cannot be null")
+  assert(zipFile ne null, "Zip file in ZipArchiveFileLookup cannot be null")
 
   override def asURLs: Seq[URL] = Seq(zipFile.toURI.toURL)
   override def asClassPathStrings: Seq[String] = Seq(zipFile.getPath)
diff --git a/compiler/src/dotty/tools/dotc/config/OutputDirs.scala b/compiler/src/dotty/tools/dotc/config/OutputDirs.scala
@@ -2,7 +2,6 @@ package dotty.tools
 package dotc
 package config
 
-import scala.language.unsafeNulls
 
 import io.*
 
@@ -30,10 +29,10 @@ class OutputDirs {
 
   /** Check that dir is exists and is a directory. */
   private def checkDir(dir: AbstractFile, name: String, allowJar: Boolean = false): AbstractFile = (
-    if (dir != null && dir.isDirectory)
+    if ((dir ne null) && dir.isDirectory)
       dir
     // was:      else if (allowJar && dir == null && Path.isJarOrZip(name, false))
-    else if (allowJar && dir == null && Jar.isJarOrZip(File(name), false))
+    else if (allowJar && (dir eq null) && Jar.isJarOrZip(File(name), false))
       new PlainFile(Path(name))
     else
       throw new FatalError(name + " does not exist or is not a directory"))
diff --git a/compiler/src/dotty/tools/dotc/config/Properties.scala b/compiler/src/dotty/tools/dotc/config/Properties.scala
@@ -2,7 +2,6 @@ package dotty.tools
 package dotc
 package config
 
-import scala.language.unsafeNulls
 
 import scala.annotation.internal.sharable
 
@@ -45,7 +44,7 @@ trait PropertiesTrait {
 
   def propIsSet(name: String): Boolean                  = System.getProperty(name) != null
   def propIsSetTo(name: String, value: String): Boolean = propOrNull(name) == value
-  def propOrElse(name: String, alt: => String): String  = Option(System.getProperty(name)).getOrElse(alt)
+  def propOrElse(name: String, alt: => String | Null): String  = Option(System.getProperty(name)).getOrElse(alt)
   def propOrEmpty(name: String): String                 = propOrElse(name, "")
   def propOrNull(name: String): String                  = propOrElse(name, null)
   def propOrNone(name: String): Option[String]          = Option(propOrNull(name))
diff --git a/compiler/src/dotty/tools/dotc/coverage/Serializer.scala b/compiler/src/dotty/tools/dotc/coverage/Serializer.scala
@@ -3,7 +3,6 @@ package coverage
 
 import java.nio.file.{Path, Paths, Files}
 import java.io.Writer
-import scala.language.unsafeNulls
 import scala.collection.mutable.StringBuilder
 
 /**
diff --git a/compiler/src/dotty/tools/dotc/sbt/APIUtils.scala b/compiler/src/dotty/tools/dotc/sbt/APIUtils.scala
@@ -1,7 +1,6 @@
 package dotty.tools.dotc
 package sbt
 
-import scala.language.unsafeNulls
 
 import core.*
 import Contexts.*
diff --git a/compiler/src/dotty/tools/dotc/transform/Splicer.scala b/compiler/src/dotty/tools/dotc/transform/Splicer.scala
@@ -1,7 +1,6 @@
 package dotty.tools.dotc
 package transform
 
-import scala.language.unsafeNulls
 
 import java.io.{PrintWriter, StringWriter}
 import java.lang.reflect.{InvocationTargetException, Method => JLRMethod}
diff --git a/compiler/src/dotty/tools/dotc/util/LRUCache.scala b/compiler/src/dotty/tools/dotc/util/LRUCache.scala
@@ -1,6 +1,5 @@
 package dotty.tools.dotc.util
 
-import scala.language.unsafeNulls
 
 import reflect.ClassTag
 import annotation.tailrec
@@ -17,7 +16,7 @@ import annotation.tailrec
  *  get promoted to be first in the queue. Elements are evicted
  *  at the `last` position.
  */
-class LRUCache[Key >: Null <: AnyRef : ClassTag, Value >: Null: ClassTag] {
+class LRUCache[Key >: Null <: AnyRef | Null : ClassTag, Value >: Null: ClassTag] {
   import LRUCache.*
   val keys: Array[Key] = new Array[Key](Retained)
   val values: Array[Value] = new Array(Retained)
diff --git a/compiler/src/dotty/tools/dotc/util/NameTransformer.scala b/compiler/src/dotty/tools/dotc/util/NameTransformer.scala
@@ -2,7 +2,6 @@ package dotty.tools
 package dotc
 package util
 
-import scala.language.unsafeNulls
 
 import core.Names.*
 
@@ -55,7 +54,7 @@ object NameTransformer {
    *  the Scala spec as well as the Java spec.
    */
   def encode(name: SimpleName): SimpleName = {
-    var buf: StringBuilder = null
+    var buf: StringBuilder | Null = null
     val len = name.length
     var i = 0
     while (i < len) {
@@ -88,11 +87,11 @@ object NameTransformer {
    */
   def decode(name: SimpleName): SimpleName = {
     //System.out.println("decode: " + name);//DEBUG
-    var buf: StringBuilder = null
+    var buf: StringBuilder | Null = null
     val len = name.length
     var i = 0
     while (i < len) {
-      var ops: OpCodes = null
+      var ops: OpCodes | Null = null
       var unicode = false
       val c = name(i)
       if (c == '$' && i + 2 < len) {
diff --git a/compiler/src/dotty/tools/dotc/util/SimpleIdentitySet.scala b/compiler/src/dotty/tools/dotc/util/SimpleIdentitySet.scala
@@ -1,6 +1,5 @@
 package dotty.tools.dotc.util
 
-import scala.language.unsafeNulls
 
 import collection.mutable
 
@@ -222,7 +221,7 @@ object SimpleIdentitySet {
     override def ++ [E >: Elem <: AnyRef](that: SimpleIdentitySet[E]): SimpleIdentitySet[E] =
       that match {
         case that: SetN[?] =>
-          var toAdd: mutable.ArrayBuffer[AnyRef] = null
+          var toAdd: mutable.ArrayBuffer[AnyRef] | Null = null
           var i = 0
           val limit = that.xs.length
           while (i < limit) {
@@ -252,7 +251,7 @@ object SimpleIdentitySet {
         case that: SetN[?] =>
           // both sets are large, optimize assuming they are similar
           // by starting from empty set and adding elements
-          var toAdd: mutable.ArrayBuffer[AnyRef] = null
+          var toAdd: mutable.ArrayBuffer[AnyRef] | Null = null
           val thisSize = this.size
           val thatSize = that.size
           val thatElems = that.xs
diff --git a/compiler/src/dotty/tools/dotc/util/SourcePosition.scala b/compiler/src/dotty/tools/dotc/util/SourcePosition.scala
@@ -2,7 +2,6 @@ package dotty.tools
 package dotc
 package util
 
-import scala.language.unsafeNulls
 
 import printing.{Showable, Printer}
 import printing.Texts.*
@@ -67,7 +66,7 @@ extends SrcPos, interfaces.SourcePosition, Showable {
   def toSynthetic: SourcePosition = withSpan(span.toSynthetic)
 
   def outermost: SourcePosition =
-    if outer == null || outer == NoSourcePosition then this else outer.outermost
+    if (outer eq null) || outer == NoSourcePosition then this else outer.outermost
 
   /** Inner most position that is contained within the `outermost` position.
    *  Most precise position that comes from the call site.
@@ -86,7 +85,7 @@ extends SrcPos, interfaces.SourcePosition, Showable {
 }
 
 /** A sentinel for a non-existing source position */
-@sharable object NoSourcePosition extends SourcePosition(NoSource, NoSpan, null) {
+@sharable object NoSourcePosition extends SourcePosition(NoSource, NoSpan) {
   override def line: Int = -1
   override def column: Int = -1
   override def toString: String = "?"
diff --git a/compiler/src/dotty/tools/io/Streamable.scala b/compiler/src/dotty/tools/io/Streamable.scala
@@ -5,7 +5,6 @@
 
 package dotty.tools.io
 
-import scala.language.unsafeNulls
 
 import java.net.URL
 import java.io.{ BufferedInputStream, InputStream }
diff --git a/compiler/src/dotty/tools/runner/ScalaClassLoader.scala b/compiler/src/dotty/tools/runner/ScalaClassLoader.scala
@@ -1,7 +1,6 @@
 package dotty.tools
 package runner
 
-import scala.language.unsafeNulls
 
 import java.lang.ClassLoader
 import java.lang.invoke.{MethodHandles, MethodType}
@@ -64,7 +63,7 @@ object ScalaClassLoader {
   def fromURLsParallelCapable(urls: Seq[URL], parent: ClassLoader | Null = null): URLClassLoader =
     new URLClassLoader(urls.toArray, if parent == null then bootClassLoader else parent)
 
-  @sharable private val bootClassLoader: ClassLoader =
+  @sharable private val bootClassLoader: ClassLoader | Null =
     if scala.util.Properties.isJavaAtLeast("9") then
       try
         ClassLoader.getSystemClassLoader.getParent
