chore: fix parameterless calls to functions (#23204)

Changes to parameterless/empty parameter list such that the code follows
the specification.

NOTE: This code shouldn't have compiled in the first place. I'm raising
an issue as soon as I finish what I'm focusing on.

Author: hamzaremmal

compiler/src/dotty/tools/MainGenericRunner.scala

@@ -158,7 +158,7 @@ object MainGenericRunner {
         .withScriptArgs(tail*)
         .noSave // -save not useful here
     case arg :: tail =>
-      val line = Try(Source.fromFile(arg).getLines.toList).toOption.flatMap(_.headOption)
+      val line = Try(Source.fromFile(arg).getLines().toList).toOption.flatMap(_.headOption)
       lazy val hasScalaHashbang = { val s = line.getOrElse("") ; s.startsWith("#!") && s.contains("scala") }
       if arg.endsWith(".scala") || arg.endsWith(".sc") || hasScalaHashbang then
         settings

compiler/src/dotty/tools/dotc/cc/root.scala

@@ -348,7 +348,7 @@ object root:
             val it = seen.iterator
             var ref: CaptureRef | Null = null
             while it.hasNext && ref == null do
-              val (k, v) = it.next
+              val (k, v) = it.next()
               if v.annot eq t.annot then ref = k
             if ref == null then
               ref = Fresh(Origin.Unknown)

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

@@ -15,7 +15,7 @@ case class VirtualDirectoryClassPath(dir: VirtualDirectory) extends ClassPath wi
     var file: AbstractFile | Null = base
     val dirParts = pathParts.init.iterator
     while (dirParts.hasNext) {
-      val dirPart = dirParts.next
+      val dirPart = dirParts.next()
       file = file.lookupName(dirPart, directory = true)
       if (file == null)
         return null

compiler/src/dotty/tools/dotc/core/Contexts.scala

@@ -135,7 +135,7 @@ object Contexts {
     def outersIterator: Iterator[Context] = new Iterator[Context] {
       var current = thiscontext
       def hasNext = current != NoContext
-      def next = { val c = current; current = current.outer; c }
+      def next() = { val c = current; current = current.outer; c }
     }
 
     def period: Period

compiler/src/dotty/tools/dotc/core/SymDenotations.scala

@@ -1141,7 +1141,7 @@ object SymDenotations {
     final def ownersIterator(using Context): Iterator[Symbol] = new Iterator[Symbol] {
       private var current = symbol
       def hasNext = current.exists
-      def next: Symbol = {
+      def next(): Symbol = {
         val result = current
         current = current.owner
         result
@@ -1418,7 +1418,7 @@ object SymDenotations {
     final def nextOverriddenSymbol(using Context): Symbol = {
       val overridden = allOverriddenSymbols
       if (overridden.hasNext)
-        overridden.next
+        overridden.next()
       else
         NoSymbol
     }
@@ -1496,10 +1496,10 @@ object SymDenotations {
       val candidates = owner.info.decls.lookupAll(name)
       def test(sym: Symbol): Symbol =
         if (sym == symbol || sym.signature == signature) sym
-        else if (candidates.hasNext) test(candidates.next)
+        else if (candidates.hasNext) test(candidates.next())
         else NoSymbol
       if (candidates.hasNext) {
-        val sym = candidates.next
+        val sym = candidates.next()
         if (candidates.hasNext) test(sym) else sym
       }
       else NoSymbol

compiler/src/dotty/tools/dotc/core/Types.scala

@@ -1630,7 +1630,7 @@ object Types extends TypeUtils {
     def underlyingIterator(using Context): Iterator[Type] = new Iterator[Type] {
       var current = Type.this
       var hasNext = true
-      def next = {
+      def next() = {
         val res = current
         hasNext = current.isInstanceOf[TypeProxy]
         if (hasNext) current = current.asInstanceOf[TypeProxy].underlying

compiler/src/dotty/tools/dotc/core/tasty/TastyPrinter.scala

@@ -60,7 +60,7 @@ object TastyPrinter:
       else if arg.endsWith(".jar") then
         val jar = JarArchive.open(Path(arg), create = false)
         try
-          for file <- jar.iterator() if file.hasTastyExtension do
+          for file <- jar.iterator if file.hasTastyExtension do
             printTasty(s"$arg ${file.path}", file.toByteArray, isBestEffortTasty = false)
         finally jar.close()
       else
@@ -123,7 +123,7 @@ class TastyPrinter(bytes: Array[Byte], isBestEffortTasty: Boolean, val testPickl
     unpickle0(new PositionSectionUnpickler(sb))
     unpickle0(new CommentSectionUnpickler(sb))
     unpickle0(new AttributesSectionUnpickler(sb))
-    sb.result
+    sb.result()
   }
 
   def unpickle0[R](sec: PrinterSectionUnpickler[R])(using NameRefs): Option[R] =
@@ -266,7 +266,7 @@ class TastyPrinter(bytes: Array[Byte], isBestEffortTasty: Boolean, val testPickl
           val value = nameAtRef(utf8Ref).toString
           sb.append(nameStr(s" ${utf8Ref.index} [$value]"))
         sb.append("\n")
-      sb.result
+      sb.result()
     }
   }
 
@@ -295,7 +295,7 @@ class TastyPrinter(bytes: Array[Byte], isBestEffortTasty: Boolean, val testPickl
       for ((_, nameRef) <- sources.iterator) {
         buf += nameRef
       }
-      NameRefs(buf.result)
+      NameRefs(buf.result())
     }
   }
 

compiler/src/dotty/tools/dotc/core/tasty/TreePickler.scala

@@ -958,7 +958,7 @@ class TreePickler(pickler: TastyPickler, attributes: Attributes) {
       val it = mp.keysIterator
       var i = 0
       while i < keys.length do
-        keys(i) = it.next
+        keys(i) = it.next()
         i += 1
       assert(!it.hasNext)
       i = 0

compiler/src/dotty/tools/dotc/inlines/Inliner.scala

@@ -683,7 +683,7 @@ class Inliner(val call: tpd.Tree)(using Context):
         // call. This way, a defensively written rewrite method can always
         // report bad inputs at the point of call instead of revealing its internals.
         val callToReport = if (enclosingInlineds.nonEmpty) enclosingInlineds.last else call
-        val ctxToReport = ctx.outersIterator.dropWhile(enclosingInlineds(using _).nonEmpty).next
+        val ctxToReport = ctx.outersIterator.dropWhile(enclosingInlineds(using _).nonEmpty).next()
         // The context in which we report should still use the existing context reporter
         val ctxOrigReporter = ctxToReport.fresh.setReporter(ctx.reporter)
         inContext(ctxOrigReporter) {

compiler/src/dotty/tools/dotc/transform/Mixin.scala

@@ -250,7 +250,7 @@ class Mixin extends MiniPhase with SymTransformer { thisPhase =>
         case Some((_, _, args)) => args.iterator
         case _ => Iterator.empty
       def nextArgument() =
-        if argsIt.hasNext then argsIt.next
+        if argsIt.hasNext then argsIt.next()
         else
           assert(
               impl.parents.forall(_.tpe.typeSymbol != mixin),

compiler/src/dotty/tools/dotc/transform/PickleQuotes.scala

@@ -139,7 +139,7 @@ class PickleQuotes extends MacroTransform {
 
       /** Get the holeContents of the transformed tree */
       def getContents() =
-        val res = holeContents.result
+        val res = holeContents.result()
         holeContents.clear()
         res
     end HoleContentExtractor

compiler/src/dotty/tools/io/AbstractFile.scala

@@ -196,7 +196,7 @@ abstract class AbstractFile extends Iterable[AbstractFile] {
   }
 
   /** Returns all abstract subfiles of this abstract directory. */
-  def iterator(): Iterator[AbstractFile]
+  def iterator: Iterator[AbstractFile]
 
   /** Drill down through subdirs looking for the target, as in lookupName.
    *  Ths target name is the last of parts.

compiler/src/dotty/tools/io/PlainFile.scala

@@ -14,7 +14,7 @@ import java.nio.file.{InvalidPathException, Paths}
 /** ''Note:  This library is considered experimental and should not be used unless you know what you are doing.'' */
 class PlainDirectory(givenPath: Directory) extends PlainFile(givenPath) {
   override val isDirectory: Boolean = true
-  override def iterator(): Iterator[PlainFile] = givenPath.list.filter(_.exists).map(new PlainFile(_))
+  override def iterator: Iterator[PlainFile] = givenPath.list.filter(_.exists).map(new PlainFile(_))
 }
 
 /** This class implements an abstract file backed by a File.

compiler/src/dotty/tools/io/VirtualDirectory.scala

@@ -43,7 +43,7 @@ extends AbstractFile {
 
   // the toList is so that the directory may continue to be
   // modified while its elements are iterated
-  def iterator(): Iterator[AbstractFile] = files.values.toList.iterator
+  def iterator: Iterator[AbstractFile] = files.values.toList.iterator
 
   override def lookupName(name: String, directory: Boolean): AbstractFile =
     (files get name filter (_.isDirectory == directory)).orNull

compiler/src/dotty/tools/io/ZipArchive.scala

@@ -220,7 +220,7 @@ final class FileZipArchive(jpath: JPath, release: Option[String]) extends ZipArc
 }
 
 final class ManifestResources(val url: URL) extends ZipArchive(null, None) {
-  def iterator(): Iterator[AbstractFile] = {
+  def iterator: Iterator[AbstractFile] = {
     val root     = new DirEntry("/", null)
     val dirs     = mutable.HashMap[String, DirEntry]("/" -> root)
     val stream   = input

compiler/test/dotty/tools/dotc/SettingsTests.scala

@@ -245,7 +245,7 @@ class SettingsTests {
       assertNotEquals(file1StateBefore, String(Files.readAllBytes(file1)))
       assertEquals(file2StateBefore, String(Files.readAllBytes(file2)))
 
-    }(Files.deleteIfExists(_), Files.deleteIfExists(_))
+    }(using Files.deleteIfExists(_), Files.deleteIfExists(_))
 
   @Test def `Output side effect is not present when setting is deprecated`: Unit =
     val result = Using.resource(Files.createTempFile("myfile", ".jar")){ file =>

compiler/test/dotty/tools/dotc/core/tasty/PathPicklingTest.scala

@@ -47,7 +47,7 @@ class PathPicklingTest {
       val sb = new StringBuffer
       val jar = JarArchive.open(Path(s"$out/out.jar"), create = false)
       try
-        for file <- jar.iterator() if file.name.endsWith(".tasty") do
+        for file <- jar.iterator if file.name.endsWith(".tasty") do
           sb.append(TastyPrinter.showContents(file.toByteArray, noColor = true, isBestEffortTasty = false))
       finally jar.close()
       sb.toString()

compiler/test/dotty/tools/utils.scala

@@ -41,7 +41,7 @@ extension (str: String) def dropExtension =
 
 private
 def withFile[T](file: File)(action: Source => T): T = resource(Source.fromFile(file, UTF_8.name))(action)
-def readLines(f: File): List[String]                = withFile(f)(_.getLines.toList)
+def readLines(f: File): List[String]                = withFile(f)(_.getLines().toList)
 def readFile(f: File): String                       = withFile(f)(_.mkString)
 
 private object Unthrown extends ControlThrowable

compiler/test/dotty/tools/vulpix/ParallelTesting.scala

@@ -838,7 +838,7 @@ trait ParallelTesting extends RunnerOrchestration { self =>
         count += 1
       for file <- files if isSourceFile(file) do
         Using.resource(Source.fromFile(file, StandardCharsets.UTF_8.name)) { source =>
-          source.getLines.zipWithIndex.foreach: (line, lineNbr) =>
+          source.getLines().zipWithIndex.foreach: (line, lineNbr) =>
             comment.findAllMatchIn(line).foreach:
               case comment("nopos-") => bump("nopos")
               case _                 => bump(s"${file.getPath}:${lineNbr+1}")
@@ -980,7 +980,7 @@ trait ParallelTesting extends RunnerOrchestration { self =>
         expectedErrors += 1
       files.filter(isSourceFile).foreach { file =>
         Using(Source.fromFile(file, StandardCharsets.UTF_8.name)) { source =>
-          source.getLines.zipWithIndex.foreach { case (line, lineNbr) =>
+          source.getLines().zipWithIndex.foreach { case (line, lineNbr) =>
             comment.findAllMatchIn(line).foreach { m =>
               m.group(2) match
                 case prefix if m.group(1).isEmpty =>