326509 – Null pointer exception from content assist looking for external reference in XText-generated editor

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Bug 326509 - Null pointer exception from content assist looking for external reference in XText-generated editor

Summary: Null pointer exception from content assist looking for external reference in ...

Status:	CLOSED FIXED

Alias:	None

Product:	TMF
Classification:	Modeling
Component:	Xtext (show other bugs)
Version:	1.0.1
Hardware:	PC Windows XP

Importance:	P3 normal (vote)
Target Milestone:	M3
Assignee:	Project Inbox
QA Contact:

URL:
Whiteboard:
Keywords:

Depends on:	327142
Blocks:
	Show dependency tree

Reported:	2010-09-29 06:18 EDT by Jérôme Fouletier
Modified:	2017-09-19 17:56 EDT (History)
CC List:	4 users (show)

See Also:

Flags:	sebastian.zarnekow: helios+ sebastian.zarnekow: indigo+

Attachments
Workaround (1.30 KB, patch) 2010-10-01 10:22 EDT, Daniel Weber	no flags	Details \| Diff
Workaround based on v1.0.1 (1.30 KB, patch) 2010-10-01 10:28 EDT, Daniel Weber	sebastian.zarnekow: iplog+	Details \| Diff
Show Obsolete (1) View All Add an attachment (proposed patch, testcase, etc.)

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Description Jérôme Fouletier

2010-09-29 06:18:07 EDT

Build Identifier: 20100917-0705

At some places in the editor, when trying to get content assist at a spot where it should be looking for an external reference, the content assist throws NPE.
Debugger investigation showed that BaseRecognizer.following[99] = null, whereas higher indexes are not, and BaseRecognizer._fsp > 100

!ENTRY org.eclipse.ui 4 4 2010-09-29 12:09:06.382
!MESSAGE "Content Assist" did not complete normally.  Please see the log for more information.

!ENTRY org.eclipse.ui 4 0 2010-09-29 12:09:06.398
!MESSAGE java.lang.NullPointerException
!STACK 0
java.lang.NullPointerException
	at org.antlr.runtime.BaseRecognizer.combineFollows(BaseRecognizer.java:457)
	at org.antlr.runtime.BaseRecognizer.computeContextSensitiveRuleFOLLOW(BaseRecognizer.java:444)
	at org.antlr.runtime.BaseRecognizer.recoverFromMismatchedElement(BaseRecognizer.java:546)
	at org.eclipse.xtext.ui.editor.contentassist.antlr.internal.AbstractInternalContentAssistParser.recoverFromMismatchedToken(AbstractInternalContentAssistParser.java:182)
	at org.antlr.runtime.BaseRecognizer.mismatch(BaseRecognizer.java:119)
	at org.eclipse.xtext.ui.editor.contentassist.antlr.internal.AbstractInternalContentAssistParser.mismatch(AbstractInternalContentAssistParser.java:354)
	at org.antlr.runtime.BaseRecognizer.match(BaseRecognizer.java:99)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__RANRef__RefAssignment_2(InternalCheckParser.java:28064)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__RANRef__Group__2__Impl(InternalCheckParser.java:22932)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__RANRef__Group__2(InternalCheckParser.java:22893)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__RANRef__Group__1(InternalCheckParser.java:22800)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__RANRef__Group__0(InternalCheckParser.java:22727)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.ruleRANRef(InternalCheckParser.java:2284)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__RanChain__RefAssignment_2(InternalCheckParser.java:27784)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__RanChain__Group__2__Impl(InternalCheckParser.java:21089)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__RanChain__Group__2(InternalCheckParser.java:21046)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__RanChain__Group__1(InternalCheckParser.java:20957)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__RanChain__Group__0(InternalCheckParser.java:20875)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.ruleRanChain(InternalCheckParser.java:2134)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__RANExp__NextAssignment_2_4(InternalCheckParser.java:27699)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__RANExp__Group_2__4__Impl(InternalCheckParser.java:20829)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__RANExp__Group_2__4(InternalCheckParser.java:20782)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__RANExp__Group_2__3(InternalCheckParser.java:20693)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__RANExp__Group_2__2(InternalCheckParser.java:20611)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__RANExp__Group_2__1(InternalCheckParser.java:20518)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__RANExp__Group_2__0(InternalCheckParser.java:20445)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__RANExp__Alternatives(InternalCheckParser.java:4473)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.ruleRANExp(InternalCheckParser.java:2059)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__Primary__Alternatives(InternalCheckParser.java:4241)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rulePrimary(InternalCheckParser.java:1984)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__SetExpression__Alternatives(InternalCheckParser.java:3976)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.ruleSetExpression(InternalCheckParser.java:1909)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__UnaryExpression__Alternatives(InternalCheckParser.java:3849)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.ruleunaryExpression(InternalCheckParser.java:1834)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__ExponentExpression__Group__0__Impl(InternalCheckParser.java:17364)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__ExponentExpression__Group__0(InternalCheckParser.java:17324)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.ruleExponentExpression(InternalCheckParser.java:1759)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__MultiplicativeExpression__Group__0__Impl(InternalCheckParser.java:16428)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__MultiplicativeExpression__Group__0(InternalCheckParser.java:16388)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rulemultiplicativeExpression(InternalCheckParser.java:1684)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__AdditiveExpression__Group__0__Impl(InternalCheckParser.java:15794)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__AdditiveExpression__Group__0(InternalCheckParser.java:15754)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.ruleadditiveExpression(InternalCheckParser.java:1609)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__ShiftExpression__Group__0__Impl(InternalCheckParser.java:15160)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__ShiftExpression__Group__0(InternalCheckParser.java:15120)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.ruleshiftExpression(InternalCheckParser.java:1534)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__RelationalExpression__Group__0__Impl(InternalCheckParser.java:14089)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__RelationalExpression__Group__0(InternalCheckParser.java:14049)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rulerelationalExpression(InternalCheckParser.java:1459)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__InstanceOfExpression__Group__0__Impl(InternalCheckParser.java:13691)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__InstanceOfExpression__Group__0(InternalCheckParser.java:13651)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.ruleinstanceOfExpression(InternalCheckParser.java:1384)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__EqualityExpression__Group__0__Impl(InternalCheckParser.java:13064)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__EqualityExpression__Group__0(InternalCheckParser.java:13024)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.ruleEqualityExpression(InternalCheckParser.java:1309)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__BitwiseAndExpression__Group__0__Impl(InternalCheckParser.java:12659)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__BitwiseAndExpression__Group__0(InternalCheckParser.java:12619)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.ruleBitwiseAndExpression(InternalCheckParser.java:1234)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__BitwiseXorExpression__Group__0__Impl(InternalCheckParser.java:12254)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__BitwiseXorExpression__Group__0(InternalCheckParser.java:12214)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.ruleBitwiseXorExpression(InternalCheckParser.java:1159)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__BitwiseOrExpression__Group__0__Impl(InternalCheckParser.java:11849)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__BitwiseOrExpression__Group__0(InternalCheckParser.java:11809)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.ruleBitwiseOrExpression(InternalCheckParser.java:1084)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__AndExpression__Group__0__Impl(InternalCheckParser.java:11444)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__AndExpression__Group__0(InternalCheckParser.java:11404)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.ruleAndExpression(InternalCheckParser.java:1009)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__OrExpression__Group__0__Impl(InternalCheckParser.java:11039)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__OrExpression__Group__0(InternalCheckParser.java:10999)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.ruleOrExpression(InternalCheckParser.java:934)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.ruleExpression(InternalCheckParser.java:862)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__VarDef__ValAssignment_2(InternalCheckParser.java:25421)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__VarDef__Group__2__Impl(InternalCheckParser.java:10891)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__VarDef__Group__2(InternalCheckParser.java:10848)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__VarDef__Group__1(InternalCheckParser.java:10779)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__VarDef__Group__0(InternalCheckParser.java:10697)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.ruleVarDef(InternalCheckParser.java:790)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__CheckStatement__Alternatives(InternalCheckParser.java:3064)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.ruleCheckStatement(InternalCheckParser.java:340)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__PseudoCode__StaAssignment_1(InternalCheckParser.java:24870)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__PseudoCode__Alternatives(InternalCheckParser.java:2895)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rulePseudoCode(InternalCheckParser.java:265)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__Check__PscAssignment_18(InternalCheckParser.java:24782)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__Check__Group__18__Impl(InternalCheckParser.java:7146)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__Check__Group__18(InternalCheckParser.java:7103)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__Check__Group__17(InternalCheckParser.java:7034)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__Check__Group__16(InternalCheckParser.java:6941)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__Check__Group__15(InternalCheckParser.java:6817)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__Check__Group__14(InternalCheckParser.java:6744)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__Check__Group__13(InternalCheckParser.java:6620)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__Check__Group__12(InternalCheckParser.java:6547)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__Check__Group__11(InternalCheckParser.java:6465)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__Check__Group__10(InternalCheckParser.java:6392)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__Check__Group__9(InternalCheckParser.java:6310)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__Check__Group__8(InternalCheckParser.java:6237)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__Check__Group__7(InternalCheckParser.java:6144)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__Check__Group__6(InternalCheckParser.java:6051)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__Check__Group__5(InternalCheckParser.java:5969)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__Check__Group__4(InternalCheckParser.java:5896)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__Check__Group__3(InternalCheckParser.java:5814)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__Check__Group__2(InternalCheckParser.java:5741)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__Check__Group__1(InternalCheckParser.java:5659)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__Check__Group__0(InternalCheckParser.java:5586)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.ruleCheck(InternalCheckParser.java:190)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__AllDefs__ChksAssignment_4(InternalCheckParser.java:24348)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__AllDefs__Group__4__Impl(InternalCheckParser.java:5504)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__AllDefs__Group__4(InternalCheckParser.java:5462)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__AllDefs__Group__3(InternalCheckParser.java:5384)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__AllDefs__Group__2(InternalCheckParser.java:5311)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__AllDefs__Group__1(InternalCheckParser.java:5229)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.rule__AllDefs__Group__0(InternalCheckParser.java:5156)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.ruleAllDefs(InternalCheckParser.java:115)
	at wide.xtext.ui.contentassist.antlr.internal.InternalCheckParser.entryRuleAllDefs(InternalCheckParser.java:77)
	at wide.xtext.ui.contentassist.antlr.CheckParser.getFollowElements(CheckParser.java:256)
	at org.eclipse.xtext.ui.editor.contentassist.antlr.AbstractContentAssistParser.getFollowElements(AbstractContentAssistParser.java:220)
	at org.eclipse.xtext.ui.editor.contentassist.antlr.ParserBasedContentAssistContextFactory.create(ParserBasedContentAssistContextFactory.java:128)
	at org.eclipse.xtext.ui.editor.contentassist.CompletionProposalComputer.exec(CompletionProposalComputer.java:48)
	at org.eclipse.xtext.ui.editor.contentassist.CompletionProposalComputer.exec(CompletionProposalComputer.java:1)
	at org.eclipse.xtext.util.concurrent.IStateAccess$AbstractImpl.readOnly(IStateAccess.java:40)
	at org.eclipse.xtext.ui.editor.model.XtextDocument.readOnly(XtextDocument.java:70)
	at org.eclipse.xtext.ui.editor.contentassist.XtextContentAssistProcessor.computeCompletionProposals(XtextContentAssistProcessor.java:79)
	at org.eclipse.jface.text.contentassist.ContentAssistant.computeCompletionProposals(ContentAssistant.java:1834)
	at org.eclipse.jface.text.contentassist.CompletionProposalPopup.computeProposals(CompletionProposalPopup.java:556)
	at org.eclipse.jface.text.contentassist.CompletionProposalPopup.access$16(CompletionProposalPopup.java:553)
	at org.eclipse.jface.text.contentassist.CompletionProposalPopup$2.run(CompletionProposalPopup.java:488)
	at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
	at org.eclipse.jface.text.contentassist.CompletionProposalPopup.showProposals(CompletionProposalPopup.java:482)
	at org.eclipse.jface.text.contentassist.ContentAssistant.showPossibleCompletions(ContentAssistant.java:1660)
	at org.eclipse.jface.text.source.SourceViewer.doOperation(SourceViewer.java:919)
	at org.eclipse.jface.text.source.projection.ProjectionViewer.doOperation(ProjectionViewer.java:1534)
	at org.eclipse.ui.texteditor.ContentAssistAction$1.run(ContentAssistAction.java:82)
	at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
	at org.eclipse.ui.texteditor.ContentAssistAction.run(ContentAssistAction.java:80)
	at org.eclipse.jface.action.Action.runWithEvent(Action.java:498)
	at org.eclipse.ui.commands.ActionHandler.execute(ActionHandler.java:185)
	at org.eclipse.ui.internal.handlers.LegacyHandlerWrapper.execute(LegacyHandlerWrapper.java:109)
	at org.eclipse.core.commands.Command.executeWithChecks(Command.java:476)
	at org.eclipse.core.commands.ParameterizedCommand.executeWithChecks(ParameterizedCommand.java:508)
	at org.eclipse.ui.internal.handlers.HandlerService.executeCommand(HandlerService.java:169)
	at org.eclipse.ui.internal.keys.WorkbenchKeyboard.executeCommand(WorkbenchKeyboard.java:468)
	at org.eclipse.ui.internal.keys.WorkbenchKeyboard.press(WorkbenchKeyboard.java:786)
	at org.eclipse.ui.internal.keys.WorkbenchKeyboard.processKeyEvent(WorkbenchKeyboard.java:885)
	at org.eclipse.ui.internal.keys.WorkbenchKeyboard.filterKeySequenceBindings(WorkbenchKeyboard.java:567)
	at org.eclipse.ui.internal.keys.WorkbenchKeyboard.access$3(WorkbenchKeyboard.java:508)
	at org.eclipse.ui.internal.keys.WorkbenchKeyboard$KeyDownFilter.handleEvent(WorkbenchKeyboard.java:123)
	at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
	at org.eclipse.swt.widgets.Display.filterEvent(Display.java:1253)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1052)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1077)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1062)
	at org.eclipse.swt.widgets.Widget.sendKeyEvent(Widget.java:1103)
	at org.eclipse.swt.widgets.Widget.sendKeyEvent(Widget.java:1099)
	at org.eclipse.swt.widgets.Widget.wmChar(Widget.java:1508)
	at org.eclipse.swt.widgets.Control.WM_CHAR(Control.java:4268)
	at org.eclipse.swt.widgets.Canvas.WM_CHAR(Canvas.java:345)
	at org.eclipse.swt.widgets.Control.windowProc(Control.java:4160)
	at org.eclipse.swt.widgets.Canvas.windowProc(Canvas.java:341)
	at org.eclipse.swt.widgets.Display.windowProc(Display.java:4873)
	at org.eclipse.swt.internal.win32.OS.DispatchMessageW(Native Method)
	at org.eclipse.swt.internal.win32.OS.DispatchMessage(OS.java:2459)
	at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3655)
	at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2640)
	at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2604)
	at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2438)
	at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:671)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
	at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:664)
	at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
	at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:115)
	at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:369)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
	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:597)
	at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:619)
	at org.eclipse.equinox.launcher.Main.basicRun(Main.java:574)
	at org.eclipse.equinox.launcher.Main.run(Main.java:1407)
	at org.eclipse.equinox.launcher.Main.main(Main.java:1383)


Reproducible: Always

Comment 1 Daniel Weber

2010-10-01 09:35:30 EDT

I just ran into the same issue and found the reference to this bug in the tmf newsgroup.

This is actually caused by a bug in org.antlr.runtime. Whether you run into this or not depends on the location where you invoke content assist. As you already pointed out, BaseRecognizer.following[99] is null. 

This array (.following) is supposed to work as a stack, but org.antlr.runtime.BaseRecognizer.pushFollow(BitSet) contains a bug:

/** Push a rule's follow set using our own hardcoded stack */
protected void pushFollow(BitSet fset) {
   if ( (_fsp +1)>=following.length ) {
      BitSet[] f = new BitSet[following.length*2];
      System.arraycopy(following, 0, f, 0, following.length-1);
      following = f;
   }
   following[++_fsp] = fset;
}

See it? Look closely ... ... ... ;) The problem is the length parameter of System.arraycopy. They do not copy the last element of the original array when growing, that's why following[99] is null and then followed by non-null elements. As long as the stack did not have to grow, you will not run into the NPE. 

The fix is simple:

      System.arraycopy(following, 0, f, 0, following.length);

I tested this by manually overwriting the method in the Xtext-generated Internal<myLanguage>Parser in the .ui project ==> NPEs are gone.

Is there a way to "inject" this change into the Xtext generator? I already tried to use a custom parser class derived from the generated one, but this spoils some reflective method invocations deep down in Xtext (getClass().getDeclaredMethods() fails to return get<rule> methods). I'd really like to work around this without manually changing generated code.

I also checked current antlr sources at http://github.com/antlr, the bug does not seem to be present there.

Comment 2 Daniel Weber

2010-10-01 09:46:13 EDT

(In reply to comment #1)
> [...] but this
> spoils some reflective method invocations deep down in Xtext
> (getClass().getDeclaredMethods() fails to return get<rule> methods). 

The methods that are missing are 

  public final EObject rule<ruleName>()

Comment 3 Daniel Weber

2010-10-01 10:22:44 EDT

Created attachment 180056 [details]
Workaround

Added org.eclipse.xtext.parser.antlr.AbstractInternalAntlrParser.pushFollow(BitSet)
to work around this problem. 

The patch is against the Helios_Final tag  in git (commit 507b5ab3875669f57ad6c62bd1ccba74a7df121d)

Comment 4 Daniel Weber

2010-10-01 10:28:45 EDT

Created attachment 180057 [details]
Workaround based on v1.0.1

Added
org.eclipse.xtext.parser.antlr.AbstractInternalAntlrParser.pushFollow(BitSet)
to work around this problem. 

The patch is against the v1.0.1 tag  in git (commit
270291576d8cf12bcaa8e65bae26cdf8c9472719)

Comment 5 Sven Efftinge

2010-10-01 15:03:45 EDT

Thanks for tracking this down.
You could add a PostProcessor to the generator in the mwe2 file. The PostProcessorallows you to do modifications to the generated files before they are written to the hard disk.

I think for the Xtext 2.0 stream we should solve this by upgrading to a new Antlr version.

Comment 6 Sebastian Zarnekow

2010-10-03 12:19:57 EDT

I applied the patch, added tests and pushed the fix to master. Thanks for analysing the issue.
The fix will be available in Indigio M3.

Comment 7 Samantha Chan

2010-10-06 11:50:12 EDT

Is it possible to apply this patch to a service release in the Eclipse 3.6 stream?  as my product is based on 3.6.

If not, can you show me a way to work around this without having to modify the generated code? I read that you can add a post-processor to modify the generated file.  Can you point me to the documentation for that?  Sorry, not sure how to do that.

Thanks!
Samantha

Comment 8 Daniel Weber

2010-10-06 13:16:18 EDT

I started a small project containing a workaround for this and another bug. See http://github.com/DanielWeber/xtextext

You just have to swap one of the generator fragments and you're done. A few lines of documentation should be coming soon :) 

In essence: In the your language's .mwe2 file, replace XtextAntlrUiGeneratorFragment with PatchedXtextAntlrUiGeneratorFragment:

// fragment = parser.antlr.XtextAntlrUiGeneratorFragment {}
fragment = com.github.xtextext.workarounds.parser.PatchedXtextAntlrUiGeneratorFragment {}

This will also make your .ui plugin depend on com.github.xtextext.workarounds, so you might have to merge the generated MANIFEST.MF if merging is disabled in the generator.

Comment 9 Sven Efftinge

2010-10-06 13:35:40 EDT

(In reply to comment #7)
> Is it possible to apply this patch to a service release in the Eclipse 3.6
> stream?  as my product is based on 3.6.

Yes, we'll do

Comment 10 Sebastian Zarnekow

2010-10-18 09:07:29 EDT

Workaround was removed from Xtext 2.0 stream since we migrated to Antlr 3.2

Comment 11 Sebastian Zarnekow

2010-11-09 09:16:47 EST

Applied workaround in Helios_Maintenance

Comment 12 Karsten Thoms

2017-09-19 17:45:57 EDT

Closing all bugs that were set to RESOLVED before Neon.0

Comment 13 Karsten Thoms

2017-09-19 17:56:56 EDT

Closing all bugs that were set to RESOLVED before Neon.0