fix for #22461 jar with empty ClassPath attribute

Author: philwalk

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

@@ -43,7 +43,7 @@ class ClassPathFactory {
     yield newClassPath(entry)
 
   def classesInExpandedPath(path: String)(using Context): IndexedSeq[ClassPath] =
-    classesInPathImpl(path, expand = true).toIndexedSeq
+    if path.trim.isEmpty then IndexedSeq.empty[ClassPath] else classesInPathImpl(path, expand = true).toIndexedSeq
 
   def classesInPath(path: String)(using Context): List[ClassPath] = classesInPathImpl(path, expand = false)
 
@@ -69,8 +69,10 @@ class ClassPathFactory {
           a <- ClassPath.expandManifestPath(file.absolutePath)
           path = java.nio.file.Paths.get(a.toURI()).nn
           if Files.exists(path)
+          entry = AbstractFile.getFile(path)
+          if Option(entry).nonEmpty
         yield
-          newClassPath(AbstractFile.getFile(path))
+          newClassPath(entry)
       else
         Seq.empty
 
@@ -79,9 +81,10 @@ class ClassPathFactory {
   end classesInPathImpl
 
   private def createSourcePath(file: AbstractFile)(using Context): ClassPath =
-    if (file.isJarOrZip)
+    val nonNull = Option(file).nonEmpty
+    if (nonNull && file.isJarOrZip)
       ZipAndJarSourcePathFactory.create(file)
-    else if (file.isDirectory)
+    else if (nonNull && file.isDirectory)
       new DirectorySourcePath(file.file)
     else
       sys.error(s"Unsupported sourcepath element: $file")

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

@@ -34,7 +34,7 @@ object FileUtils {
     def isScalaOrJavaSource: Boolean = !file.isDirectory && file.ext.isScalaOrJava
 
     // TODO do we need to check also other files using ZipMagicNumber like in scala.tools.nsc.io.Jar.isJarOrZip?
-    def isJarOrZip: Boolean = file.ext.isJarOrZip
+    def isJarOrZip: Boolean = Option(file).nonEmpty && file.ext.isJarOrZip
 
     /**
      * Safe method returning a sequence containing one URL representing this file, when underlying file exists,