Fix scala.runtime.{Null$, Nothing$} tasty

Author: nicolasstucki

compiler/src/dotty/tools/dotc/classpath/DirectoryClassPath.scala

@@ -288,9 +288,7 @@ case class DirectoryClassPath(dir: JFile) extends JFileDirectoryLookup[ClassFile
 
   protected def createFileEntry(file: AbstractFile): ClassFileEntryImpl = ClassFileEntryImpl(file)
   protected def isMatchingFile(f: JFile): Boolean =
-    def isClassWithNoTasty =
-      f.isClass && !Files.exists(f.toPath.resolveSibling(f.getName.stripSuffix(".class").stripSuffix("$") + ".tasty"))
-    f.isTasty || isClassWithNoTasty
+    f.isTasty || (f.isClass && f.classToTasty.isEmpty)
 
   private[dotty] def classes(inPackage: PackageName): Seq[ClassFileEntry] = files(inPackage)
 }

compiler/src/dotty/tools/dotc/classpath/FileUtils.scala

@@ -32,6 +32,15 @@ object FileUtils {
      * and returning given default value in other case
      */
     def toURLs(default: => Seq[URL] = Seq.empty): Seq[URL] = if (file.file == null) default else Seq(file.toURL)
+
+    /** Returns the tasty file associated with this class file */
+    def classToTasty: Option[AbstractFile] =
+      assert(file.isClass, s"non-class: $file")
+      val parent = file match  // TODO: simplify when #3552 is fixed
+        case file: io.ZipArchive#Entry => file.parent
+        case _ => file.container
+      val tastyName = classNameToTasty(file.name)
+      Option(parent.lookupName(tastyName, directory = false))
   }
 
   extension (file: JFile) {
@@ -41,6 +50,14 @@ object FileUtils {
     // FIXME: drop last condition when we stop being compatible with Scala 2.11
 
     def isTasty: Boolean = file.isFile && file.getName.endsWith(SUFFIX_TASTY)
+
+    /** Returns the tasty file associated with this class file */
+    def classToTasty: Option[JFile] =
+      assert(file.isClass, s"non-class: $file")
+      val tastyName = classNameToTasty(file.getName.stripSuffix(".class"))
+      val tastyPath = file.toPath.resolveSibling(tastyName)
+      if java.nio.file.Files.exists(tastyPath) then Some(tastyPath.toFile) else None
+
   }
 
   private val SUFFIX_CLASS = ".class"
@@ -86,4 +103,12 @@ object FileUtils {
   def mkFileFilter(f: JFile => Boolean): FileFilter = new FileFilter {
     def accept(pathname: JFile): Boolean = f(pathname)
   }
+
+  private def classNameToTasty(fileName: String): String =
+    val className = fileName.stripSuffix(".class")
+    if className.endsWith("$")
+      && className != "Null$" // scala.runtime.Null$
+      && className != "Nothing$" // scala.runtime.Nothing$
+    then className.stripSuffix("$") + ".tasty"
+    else className + ".tasty"
 }

compiler/src/dotty/tools/dotc/classpath/VirtualDirectoryClassPath.scala

@@ -53,9 +53,5 @@ case class VirtualDirectoryClassPath(dir: VirtualDirectory) extends ClassPath wi
 
   protected def createFileEntry(file: AbstractFile): ClassFileEntryImpl = ClassFileEntryImpl(file)
   protected def isMatchingFile(f: AbstractFile): Boolean =
-    def tastyFile: AbstractFile | Null =
-      val tastyFileName = f.name.stripSuffix(".class").stripSuffix("$") + ".tasty"
-      f.container.lookupName(tastyFileName, directory = false)
-    def isClassWithNoTasty = f.isClass && tastyFile == null
-    f.isTasty || isClassWithNoTasty
+    f.isTasty || (f.isClass && f.classToTasty.isEmpty)
 }

compiler/src/dotty/tools/dotc/classpath/ZipAndJarFileLookupFactory.scala

@@ -61,14 +61,7 @@ object ZipAndJarClassPathFactory extends ZipAndJarFileLookupFactory {
 
     override protected def createFileEntry(file: FileZipArchive#Entry): ClassFileEntryImpl = ClassFileEntryImpl(file)
     override protected def isRequiredFileType(file: AbstractFile): Boolean =
-      def tastyFile: AbstractFile | Null =
-        val parent = file match  // TODO: simplify when #3552 is fixed
-          case classfile: ZipArchive#Entry => classfile.parent
-          case _ => file.container
-        val tastyFileName = file.name.stripSuffix(".class").stripSuffix("$") + ".tasty"
-        parent.lookupName(tastyFileName, directory = false)
-      def isClassWithNoTasty = file.isClass && tastyFile == null
-      file.isTasty || isClassWithNoTasty
+      file.isTasty || (file.isClass && file.classToTasty.isEmpty)
   }
 
   /**

compiler/src/dotty/tools/dotc/core/classfile/ClassfileParser.scala

@@ -23,6 +23,7 @@ import scala.annotation.switch
 import typer.Checking.checkNonCyclic
 import io.{AbstractFile, ZipArchive}
 import scala.util.control.NonFatal
+import dotty.tools.dotc.classpath.FileUtils.classToTasty
 
 object ClassfileParser {
   /** Marker trait for unpicklers that can be embedded in classfiles. */
@@ -941,23 +942,19 @@ class ClassfileParser(
         val attrLen = in.nextInt
         val bytes = in.nextBytes(attrLen)
         if (attrLen == 16) { // A tasty attribute with that has only a UUID (16 bytes) implies the existence of the .tasty file
-          val parent = classfile match  // TODO: simplify when #3552 is fixed
-            case classfile: io.ZipArchive#Entry => classfile.parent
-            case _ => classfile.container
-          val tastyFileName = classfile.name.stripSuffix(".class") + ".tasty"
-          val tastyFile = parent.lookupName(tastyFileName, directory = false)
-          if tastyFile == null then
-            report.error(em"Could not find TASTY file $tastyFileName in $parent")
-          else
-            val tastyLoader = new TastyLoader(tastyFile)
-            val tastyBytes: Array[Byte] = tastyLoader.loadTastyBytes()
-            val expectedUUID =
-              val reader = new TastyReader(bytes, 0, 16)
-              new UUID(reader.readUncompressedLong(), reader.readUncompressedLong())
-            val tastyUUID =
-              new TastyHeaderUnpickler(tastyBytes).readHeader()
-            if (expectedUUID != tastyUUID)
-              report.warning(s"$classfile is out of sync with its TASTy file. Loaded TASTy file. Try cleaning the project to fix this issue", NoSourcePosition)
+          classfile.classToTasty match
+            case None =>
+              report.error(em"Could not find TASTY for $classfile")
+            case Some(tastyFile) =>
+              val tastyLoader = new TastyLoader(tastyFile)
+              val tastyBytes: Array[Byte] = tastyLoader.loadTastyBytes()
+              val expectedUUID =
+                val reader = new TastyReader(bytes, 0, 16)
+                new UUID(reader.readUncompressedLong(), reader.readUncompressedLong())
+              val tastyUUID =
+                new TastyHeaderUnpickler(tastyBytes).readHeader()
+              if (expectedUUID != tastyUUID)
+                report.warning(s"$classfile is out of sync with its TASTy file. Loaded TASTy file. Try cleaning the project to fix this issue", NoSourcePosition)
             return None
         }
         else