VS crashing when clicking on Intellisense in Immediate window

[vsccarl]

Version Used:
d15.6\27329.01 with olegtk/FixIntellisenseInImmediate
Roslyn 2.7.0.6252601
Steps to Reproduce:

1. Create a new VB Console App
2. Add

Dim number As Integer
number = 5

3. Set a breakpoint on line 6 End Sub
4. F5
5. Open immediate window and start typing num to bring up intellisense
6. Double click on number in intellisense dialog

Expected Behavior:
The variable is inserted into the immediate window.

Actual Behavior:
VS Crashes

Log:

Application: devenv.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.InvalidOperationException
   at System.ThrowHelper.ThrowInvalidOperationException(System.ExceptionResource)
   at System.Collections.Generic.Queue`1[[Microsoft.VisualStudio.Text.SnapshotSpan, Microsoft.VisualStudio.Text.Data, Version=15.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a]].Dequeue()
   at Microsoft.CodeAnalysis.Editor.Implementation.IntelliSense.DisconnectedBufferGraph.MapDownToSnapshot(Microsoft.VisualStudio.Text.Span, Microsoft.VisualStudio.Text.Projection.IProjectionSnapshot, Microsoft.VisualStudio.Text.ITextSnapshot)
   at Microsoft.CodeAnalysis.Editor.Implementation.IntelliSense.DisconnectedBufferGraph.GetSubjectBufferTextSpanInViewBuffer(Microsoft.CodeAnalysis.Text.TextSpan)
   at Microsoft.CodeAnalysis.Editor.Implementation.IntelliSense.Completion.Controller.SetCaretPosition(Int32)
   at Microsoft.CodeAnalysis.Editor.Implementation.IntelliSense.Completion.Controller.Commit(Microsoft.CodeAnalysis.Completion.CompletionItem, Microsoft.CodeAnalysis.Editor.Implementation.IntelliSense.Completion.Model, System.Nullable`1<Char>, Microsoft.VisualStudio.Text.ITextSnapshot, System.Action)
   at Microsoft.CodeAnalysis.Editor.Implementation.IntelliSense.Completion.Controller.CommitItem(Microsoft.CodeAnalysis.Completion.CompletionItem)
   at Microsoft.CodeAnalysis.Editor.Implementation.IntelliSense.Completion.Controller+Session.OnPresenterSessionItemCommitted(System.Object, Microsoft.CodeAnalysis.Editor.CompletionItemEventArgs)
   at Microsoft.CodeAnalysis.Editor.Implementation.IntelliSense.Completion.Presentation.CompletionPresenterSession.OnCompletionItemCommitted(Microsoft.CodeAnalysis.Completion.CompletionItem)
   at Microsoft.CodeAnalysis.Editor.Implementation.IntelliSense.Completion.Presentation.CustomCommitCompletion.Commit()
   at Microsoft.VisualStudio.Language.Intellisense.Implementation.CompletionSession.Commit()
   at Microsoft.VisualStudio.Language.Intellisense.Implementation.DefaultCompletionSetPresenter.OnListBox_MouseDoubleClick(System.Object, System.Windows.Input.MouseButtonEventArgs)
   at System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler(System.Delegate, System.Object)
   at System.Windows.RoutedEventArgs.InvokeHandler(System.Delegate, System.Object)
   at System.Windows.RoutedEventHandlerInfo.InvokeHandler(System.Object, System.Windows.RoutedEventArgs)
   at System.Windows.EventRoute.InvokeHandlersImpl(System.Object, System.Windows.RoutedEventArgs, Boolean)
   at System.Windows.UIElement.RaiseEventImpl(System.Windows.DependencyObject, System.Windows.RoutedEventArgs)
   at System.Windows.UIElement.RaiseEvent(System.Windows.RoutedEventArgs)
   at System.Windows.Controls.Control.OnMouseDoubleClick(System.Windows.Input.MouseButtonEventArgs)
   at System.Windows.Controls.Control.HandleDoubleClick(System.Object, System.Windows.Input.MouseButtonEventArgs)
   at System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler(System.Delegate, System.Object)
   at System.Windows.RoutedEventArgs.InvokeHandler(System.Delegate, System.Object)
   at System.Windows.RoutedEventHandlerInfo.InvokeHandler(System.Object, System.Windows.RoutedEventArgs)
   at System.Windows.EventRoute.InvokeHandlersImpl(System.Object, System.Windows.RoutedEventArgs, Boolean)
   at System.Windows.UIElement.ReRaiseEventAs(System.Windows.DependencyObject, System.Windows.RoutedEventArgs, System.Windows.RoutedEvent)
   at System.Windows.UIElement.OnMouseDownThunk(System.Object, System.Windows.Input.MouseButtonEventArgs)
   at System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler(System.Delegate, System.Object)
   at System.Windows.RoutedEventArgs.InvokeHandler(System.Delegate, System.Object)
   at System.Windows.RoutedEventHandlerInfo.InvokeHandler(System.Object, System.Windows.RoutedEventArgs)
   at System.Windows.EventRoute.InvokeHandlersImpl(System.Object, System.Windows.RoutedEventArgs, Boolean)
   at System.Windows.UIElement.RaiseEventImpl(System.Windows.DependencyObject, System.Windows.RoutedEventArgs)
   at System.Windows.UIElement.RaiseTrustedEvent(System.Windows.RoutedEventArgs)
   at System.Windows.UIElement.RaiseEvent(System.Windows.RoutedEventArgs, Boolean)
   at System.Windows.Input.InputManager.ProcessStagingArea()
   at System.Windows.Input.InputManager.ProcessInput(System.Windows.Input.InputEventArgs)
   at System.Windows.Input.InputProviderSite.ReportInput(System.Windows.Input.InputReport)
   at System.Windows.Interop.HwndMouseInputProvider.ReportInput(IntPtr, System.Windows.Input.InputMode, Int32, System.Windows.Input.RawMouseActions, Int32, Int32, Int32)
   at System.Windows.Interop.HwndMouseInputProvider.FilterMessage(IntPtr, MS.Internal.Interop.WindowMessage, IntPtr, IntPtr, Boolean ByRef)
   at System.Windows.Interop.HwndSource.InputFilterMessage(IntPtr, Int32, IntPtr, IntPtr, Boolean ByRef)
   at MS.Win32.HwndWrapper.WndProc(IntPtr, Int32, IntPtr, IntPtr, Boolean ByRef)
   at MS.Win32.HwndSubclass.DispatcherCallbackOperation(System.Object)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(System.Delegate, System.Object, Int32)
   at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(System.Object, System.Delegate, System.Object, Int32, System.Delegate)
   at System.Windows.Threading.Dispatcher.LegacyInvokeImpl(System.Windows.Threading.DispatcherPriority, System.TimeSpan, System.Delegate, System.Object, Int32)
   at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr, Int32, IntPtr, IntPtr)

[olegtk]

Note: it also repros in VS 15.5 so it's not a recent regression.

[sharwell]

📝 Make sure to enable the corresponding test from #25814 when this is fixed.

[AmadeusW]

When user presses Tab, the edit comes out fine. When user double-clicks the item, the base buffer (containing "num") is read only, and no edit is made. I will continue investigating this.

[AmadeusW]

First thing that happens when user presses Tab is removing the ReadOnly flag in DebuggerIntellisenseFilter.ExecuteVisualStudio2000

We actually remove this flag pretty frequently (every time user types), but just before user clicks on the completion item, the flag is set to true

[AmadeusW]

The read only flag is set to true in src\env\msenv\core\cmdwin.cpp when we return from InternalExec({5efc7975-14bc-11cf-9b2b-00aa00573819}, 770, 0, 0x00000000, 0x00000000), in the destructor of CAutoReadOnlySetter: src\env\inc\AutoReadOnlySetter.h:42

I'm not sure what this is and why this is being called, but the Tab handler explicitly removes the ReadOnly flag, while the Click handler does not.

A possible fix would be to reset the read only flag of the buffer when handling the click event in intellisense

[tmat]

@AmadeusW Your help with figuring this out is appreciated.

[tmat]

Fixed by #28131

[sharwell]

📝 Make sure to enable the corresponding test from #25814 when this is fixed.

@tmat 😑