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),