Aladdin - Scala Bugtracking
[#572] project: compiler priority: high category: bug
submitter assigned to status date submitted
Sean _ noise 2006-04-24 16:13:38.0
subject presentation compiler crash
code 
package lampion.collections;

object DirX {
  abstract class Dir {
    def reverse : Dir;
  }
  object BEFORE extends Dir {
    def reverse = AFTER;
  }
  object AFTER  extends Dir {
    def reverse = BEFORE;
  }
}
import DirX._;
abstract class Linked {
  type Node <: Node0;
  
  abstract class Node0 {
  	var next : Node = _;
    var prev : Node = _;
    
    def get(dir : Dir) = if (dir == BEFORE) prev; else next;
    private def set(dir : Dir, node : Node) = 
      if (dir == BEFORE) prev = node; else next = node;
    
    def link(dir : Dir, node : Node) = {
      assert(get(dir) == null);
      assert(node.get(dir.reverse) == null);
      set(dir, node);
      node.set(dir.reverse(), node);
    }
  }
}
what happened 
Notice that the code is incorrect because reverse() on the above last line is used rather than the correct rever\
se. When loaded in presentation compiler (running only until type checking):

java.lang.Error: tail of empty list
	at scala.Predef$.error(Predef.scala:155)
	at scala.Nil$.tail(List.scala:1063)
	at scala.tools.nsc.typechecker.SyntheticMethods$class.forwardingMethod$0(SyntheticMethods.scala:84)
	at scala.tools.nsc.typechecker.SyntheticMethods$class.addSyntheticMethods(SyntheticMethods.scala:168)
	at scala.tools.nsc.Global$analyzer$.addSyntheticMethods(Global.scala:224)
	at scala.tools.nsc.typechecker.Typers$Typer.typedClassDef(Typers.scala:627)
	at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:1278)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:1606)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:1632)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$43.apply(Typers.scala:960)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$43.apply(Typers.scala:950)
	at scala.List$.loop$0(List.scala:232)
	at scala.List$.mapConserve(List.scala:249)
	at scala.tools.nsc.typechecker.Typers$Typer.typedStats(Typers.scala:950)
	at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:1274)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:1606)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:1632)
	at scala.tools.nsc.typechecker.Analyzer$typerFactory$$anon$1.apply(Analyzer.scala:38)
	at scala.tools.nsc.Global$GlobalPhase.applyPhase(Global.scala:213)
	at scala.tools.nsc.Global$GlobalPhase$$anonfun$1.apply(Global.scala:202)
	at scala.tools.nsc.Global$GlobalPhase$$anonfun$1.apply(Global.scala:202)
	at scala.Iterator$class.foreach(Iterator.scala:285)
	at scala.collection.mutable.ListBuffer$$anon$0.foreach(ListBuffer.scala:216)
	at scala.tools.nsc.Global$GlobalPhase.run(Global.scala:202)
	at scala.tools.nsc.Global$Run.compileSources(Global.scala:432)
	at ch.epfl.lamp.sdt.build.ScalaCompilerManager$SemanticCompiler.unitFor(ScalaCompilerManager.java:322)
	at ch.epfl.lamp.sdt.build.ScalaCompilerManager$SemanticCompiler.tokensFor(ScalaCompilerManager.java:338)
	at ch.epfl.lamp.sdt.core.ScalaProject.refreshTokens(ScalaProject.java:160)
	at ch.epfl.lamp.sdt.ui.actions.HighlightAction.run(HighlightAction.java:91)
	at ch.epfl.lamp.sdt.ui.actions.HighlightAction.run(HighlightAction.java:77)
	at ch.epfl.lamp.sdt.ui.actions.HighlightAction$1.run(HighlightAction.java:61)
	at ch.epfl.lamp.sdt.ui.actions.HighlightAction.run(HighlightAction.java:65)
	at ch.epfl.lamp.sdt.ui.actions.HighlightAction.run(HighlightAction.java:49)
	at ch.epfl.lamp.sdt.ui.actions.HighlightAction.run(HighlightAction.java:47)
	at org.eclipse.jface.action.Action.runWithEvent(Action.java:492)
	at org.eclipse.ui.commands.ActionHandler.execute(ActionHandler.java:182)
	at org.eclipse.ui.internal.handlers.LegacyHandlerWrapper.execute(LegacyHandlerWrapper.java:109)
	at org.eclipse.core.commands.Command.executeWithChecks(Command.java:460)
	at org.eclipse.core.commands.ParameterizedCommand.executeWithChecks(ParameterizedCommand.java:421)
	at org.eclipse.ui.internal.handlers.HandlerService.executeCommand(HandlerService.java:160)
	at org.eclipse.ui.internal.keys.WorkbenchKeyboard.executeCommand(WorkbenchKeyboard.java:466)
	at org.eclipse.ui.internal.keys.WorkbenchKeyboard.press(WorkbenchKeyboard.java:798)
	at org.eclipse.ui.internal.keys.WorkbenchKeyboard.processKeyEvent(WorkbenchKeyboard.java:845)
	at org.eclipse.ui.internal.keys.WorkbenchKeyboard.filterKeySequenceBindings(WorkbenchKeyboard.java:563)
	at org.eclipse.ui.internal.keys.WorkbenchKeyboard.access$3(WorkbenchKeyboard.java:506)
	at org.eclipse.ui.internal.keys.WorkbenchKeyboard$KeyDownFilter.handleEvent(WorkbenchKeyboard.java:122)
	at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:66)
	at org.eclipse.swt.widgets.Display.filterEvent(Display.java:1336)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1073)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1098)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1083)
	at org.eclipse.swt.widgets.Widget.sendKeyEvent(Widget.java:1110)
	at org.eclipse.swt.widgets.Widget.gtk_key_press_event(Widget.java:652)
	at org.eclipse.swt.widgets.Control.gtk_key_press_event(Control.java:2045)
	at org.eclipse.swt.widgets.Composite.gtk_key_press_event(Composite.java:608)
	at org.eclipse.swt.widgets.Widget.windowProc(Widget.java:1423)
	at org.eclipse.swt.widgets.Display.windowProc(Display.java:3790)
	at org.eclipse.swt.internal.gtk.OS._gtk_main_do_event(Native Method)
	at org.eclipse.swt.internal.gtk.OS.gtk_main_do_event(OS.java:5162)
	at org.eclipse.swt.widgets.Display.eventProc(Display.java:1128)
	at org.eclipse.swt.internal.gtk.OS._g_main_context_iteration(Native Method)
	at org.eclipse.swt.internal.gtk.OS.g_main_context_iteration(OS.java:1407)
	at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:2836)
	at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:1899)
	at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:1863)
	at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:417)
	at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:143)
	at org.eclipse.ui.internal.ide.IDEApplication.run(IDEApplication.java:106)
	at org.eclipse.core.internal.runtime.PlatformActivator$1.run(PlatformActivator.java:99)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:92)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:68)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:374)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:169)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:585)
	at org.eclipse.core.launcher.Main.invokeFramework(Main.java:338)
	at org.eclipse.core.launcher.Main.basicRun(Main.java:282)
	at org.eclipse.core.launcher.Main.run(Main.java:977)
	at org.eclipse.core.launcher.Main.main(Main.java:952)
what expected
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Changes of this bug report
Martin  edited on  2006-04-25 17:21:19.0