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While trying to reproduce the problem filed as bug 483467 I managed to produce another exception package bla; import java.util.Optional; import java.util.concurrent.CompletableFuture; public class Dummy { public Optional<String> t() { return Optional.empty(); } public CompletableFuture<Integer> t2() { return CompletableFuture.supplyAsync( () -> { t() .map( s -> { return s+"0"; })/*. auto complete at this point*/; return null; } ); } } The structure of the real code is similar to this but this code does reveal another exception java.lang.NullPointerException at org.eclipse.jdt.internal.compiler.lookup.ParameterizedGenericMethodBinding.computeCompatibleMethod18(ParameterizedGenericMethodBinding.java:212) at org.eclipse.jdt.internal.compiler.lookup.ParameterizedGenericMethodBinding.computeCompatibleMethod(ParameterizedGenericMethodBinding.java:82) at org.eclipse.jdt.internal.compiler.lookup.Scope.computeCompatibleMethod(Scope.java:743) at org.eclipse.jdt.internal.compiler.lookup.Scope.computeCompatibleMethod(Scope.java:700) at org.eclipse.jdt.internal.compiler.lookup.Scope.findMethod0(Scope.java:1645) at org.eclipse.jdt.internal.compiler.lookup.Scope.findMethod(Scope.java:1546) at org.eclipse.jdt.internal.compiler.lookup.Scope.getMethod(Scope.java:2822) at org.eclipse.jdt.internal.compiler.ast.MessageSend.findMethodBinding(MessageSend.java:898) at org.eclipse.jdt.internal.compiler.ast.MessageSend.resolveType(MessageSend.java:712) at org.eclipse.jdt.internal.codeassist.complete.CompletionOnMemberAccess.resolveType(CompletionOnMemberAccess.java:56) at org.eclipse.jdt.internal.compiler.ast.Expression.resolve(Expression.java:1020) at org.eclipse.jdt.internal.compiler.ast.Block.resolve(Block.java:117) at org.eclipse.jdt.internal.compiler.ast.LambdaExpression.resolveType(LambdaExpression.java:429) at org.eclipse.jdt.internal.compiler.ast.MessageSend.resolveType(MessageSend.java:667) at org.eclipse.jdt.internal.codeassist.complete.CompletionOnMemberAccess.resolveType(CompletionOnMemberAccess.java:56) at org.eclipse.jdt.internal.compiler.ast.Expression.resolve(Expression.java:1020) at org.eclipse.jdt.internal.compiler.ast.Block.resolve(Block.java:117) at org.eclipse.jdt.internal.compiler.ast.LambdaExpression.resolveType(LambdaExpression.java:429) at org.eclipse.jdt.internal.compiler.ast.ASTNode.resolvePolyExpressionArguments(ASTNode.java:680) at org.eclipse.jdt.internal.compiler.ast.MessageSend.findMethodBinding(MessageSend.java:905) at org.eclipse.jdt.internal.compiler.ast.MessageSend.resolveType(MessageSend.java:712) at org.eclipse.jdt.internal.compiler.ast.Expression.resolve(Expression.java:1020) at org.eclipse.jdt.internal.compiler.ast.Block.resolve(Block.java:117) at org.eclipse.jdt.internal.compiler.ast.LambdaExpression.resolveType(LambdaExpression.java:429) at org.eclipse.jdt.internal.compiler.ast.ASTNode.resolvePolyExpressionArguments(ASTNode.java:680) at org.eclipse.jdt.internal.compiler.ast.MessageSend.findMethodBinding(MessageSend.java:905) at org.eclipse.jdt.internal.compiler.ast.MessageSend.resolveType(MessageSend.java:712) at org.eclipse.jdt.internal.compiler.ast.Expression.resolve(Expression.java:1020) at org.eclipse.jdt.internal.compiler.ast.AbstractMethodDeclaration.resolveStatements(AbstractMethodDeclaration.java:641) at org.eclipse.jdt.internal.compiler.ast.MethodDeclaration.resolveStatements(MethodDeclaration.java:309) at org.eclipse.jdt.internal.compiler.ast.AbstractMethodDeclaration.resolve(AbstractMethodDeclaration.java:551) at org.eclipse.jdt.internal.compiler.ast.TypeDeclaration.resolve(TypeDeclaration.java:1188) at org.eclipse.jdt.internal.compiler.ast.TypeDeclaration.resolve(TypeDeclaration.java:1301) at org.eclipse.jdt.internal.compiler.ast.CompilationUnitDeclaration.resolve(CompilationUnitDeclaration.java:590) at org.eclipse.jdt.internal.codeassist.CompletionEngine.complete(CompletionEngine.java:1923) at org.eclipse.jdt.internal.core.Openable.codeComplete(Openable.java:131) at org.eclipse.jdt.internal.core.CompilationUnit.codeComplete(CompilationUnit.java:357) at org.eclipse.jdt.internal.core.CompilationUnit.codeComplete(CompilationUnit.java:345) at org.eclipse.jdt.internal.ui.text.java.JavaCompletionProposalComputer.internalComputeCompletionProposals(JavaCompletionProposalComputer.java:244) at org.eclipse.jdt.internal.ui.text.java.JavaCompletionProposalComputer.computeCompletionProposals(JavaCompletionProposalComputer.java:206) at org.eclipse.jdt.internal.ui.text.java.JavaTypeCompletionProposalComputer.computeCompletionProposals(JavaTypeCompletionProposalComputer.java:63) at org.eclipse.jdt.internal.ui.text.java.CompletionProposalComputerDescriptor.computeCompletionProposals(CompletionProposalComputerDescriptor.java:333) at org.eclipse.jdt.internal.ui.text.java.CompletionProposalCategory.computeCompletionProposals(CompletionProposalCategory.java:337) at org.eclipse.jdt.internal.ui.text.java.ContentAssistProcessor.collectProposals(ContentAssistProcessor.java:322) at org.eclipse.jdt.internal.ui.text.java.ContentAssistProcessor.computeCompletionProposals(ContentAssistProcessor.java:279) at org.eclipse.jface.text.contentassist.ContentAssistant$5.run(ContentAssistant.java:1904) at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42) at org.eclipse.jface.text.contentassist.ContentAssistant.computeCompletionProposals(ContentAssistant.java:1902) at org.eclipse.jface.text.contentassist.CompletionProposalPopup.computeProposals(CompletionProposalPopup.java:573) at org.eclipse.jface.text.contentassist.CompletionProposalPopup.access$16(CompletionProposalPopup.java:570) at org.eclipse.jface.text.contentassist.CompletionProposalPopup$2.run(CompletionProposalPopup.java:505) at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70) at org.eclipse.jface.text.contentassist.CompletionProposalPopup.showProposals(CompletionProposalPopup.java:499) at org.eclipse.jface.text.contentassist.ContentAssistant$2.run(ContentAssistant.java:384) at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35) at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:135) at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:4155) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3772) at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$4.run(PartRenderingEngine.java:1127) at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:337) at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1018) at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:156) at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:654) at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:337) at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:598) at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:150) at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:139) at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:134) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:104) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:380) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:235) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:669) at org.eclipse.equinox.launcher.Main.basicRun(Main.java:608) at org.eclipse.equinox.launcher.Main.run(Main.java:1515)
Cool! The immediate issue is just a dubious null element in the array MessageSend.argumentTypes, which shouldn't occur. BUT, trying to hunt for the root cause I see the debugger throwing SOE while evaluation argument.toString(). And here we see as the reason the dreaded cyclic AST structure, which has been observed in similar situations before. In this case we have LambdaExpression (id=10949) "s -> { <unprintable> }" -> body[4] [0] ReturnStatement "return (s + "0");" [1] CompletionOnMemberAccess <unprintable> [2] EmptyStatement ";" [3] ReturnStatement "return null;" Expanding body[1] = CompletionOnMemberAccess: -> receiver = MessageSend <unprintable> -> receiver = MessageSend ("t()") -> selector = "map" -> arguments= { [0] = LambdaExpression (id=10949) !!!! } -> token = [] Trying to manually render this we get s.t. like (s) -> { return (s + "0"); t().map( (s) -> { <repeat at return (s + "0") ... > }.| // complete here ; return null; } where the corresponding input was: () -> { t().map( (s) -> { return s+"0"; }).| // complete here return null; } Looks like s.t. completely messed up the parser stacks!
Bulk move: too late for 4.6 M7. Very likely has to be moved out of 4.6 entirely.
Not going to make it in 4.6. Moving out.
bulk move out of 4.8
Bulk move out of 4.9
This bug hasn't had any activity in quite some time. Maybe the problem got resolved, was a duplicate of something else, or became less pressing for some reason - or maybe it's still relevant but just hasn't been looked at yet. If you have further information on the current state of the bug, please add it. The information can be, for example, that the problem still occurs, that you still want the feature, that more information is needed, or that the bug is (for whatever reason) no longer relevant. -- The automated Eclipse Genie.
