SigHelp: ArgumentException: argumentCount < argumentIndex. 2 < 3

[KirillOsenkov]

1. Paste this code

class C
{
    void Main()
    {
        M(0, d)
    }

    void M(int a, int b = 0, int c = 0, int d = 0) { }
}

2. place the caret after d and before ) in the call to M
3. Ctrl+Shift+Space to bring up sig help (IMPORTANT!)
4. press :

Actual:

System.ArgumentException: argumentCount < argumentIndex. 2 < 3
Parameter name: argumentIndex
   at new Microsoft.CodeAnalysis.SignatureHelp.SignatureHelpItems(IList<SignatureHelpItem> items, TextSpan applicableSpan, int argumentIndex, int argumentCount, string argumentName, int? selectedItem) in C:/Roslyn/src/Features/Core/Portable/SignatureHelp/SignatureHelpItems.cs:line 76
   at SignatureHelpItems Microsoft.CodeAnalysis.SignatureHelp.AbstractSignatureHelpProvider.CreateSignatureHelpItems(IList<SignatureHelpItem> items, TextSpan applicableSpan, SignatureHelpState? state, int? selectedItemIndex, int parameterIndexOverride) in C:/Roslyn/src/Features/Core/Portable/SignatureHelp/AbstractSignatureHelpProvider.cs:line 68
   at async Task<SignatureHelpItems> Microsoft.CodeAnalysis.CSharp.SignatureHelp.InvocationExpressionSignatureHelpProviderBase.GetItemsWorkerAsync(Document document, int position, SignatureHelpTriggerInfo triggerInfo, SignatureHelpOptions options, CancellationToken cancellationToken) in C:/Roslyn/src/Features/CSharp/Portable/SignatureHelp/InvocationExpressionSignatureHelpProvider.cs:line 126
   at void System.Runtime.CompilerServices.AsyncTaskMethodBuilder<TResult>.Start<TStateMachine>(ref TStateMachine stateMachine)
   at Task<SignatureHelpItems> Microsoft.CodeAnalysis.CSharp.SignatureHelp.InvocationExpressionSignatureHelpProviderBase.GetItemsWorkerAsync(Document document, int position, SignatureHelpTriggerInfo triggerInfo, SignatureHelpOptions options, CancellationToken cancellationToken)
   at async Task<SignatureHelpItems> Microsoft.CodeAnalysis.SignatureHelp.AbstractSignatureHelpProvider.GetItemsAsync(Document document, int position, SignatureHelpTriggerInfo triggerInfo, SignatureHelpOptions options, CancellationToken cancellationToken) in C:/Roslyn/src/Features/Core/Portable/SignatureHelp/AbstractSignatureHelpProvider.cs:line 245
   at void System.Runtime.CompilerServices.AsyncTaskMethodBuilder<TResult>.Start<TStateMachine>(ref TStateMachine stateMachine)
   at Task<SignatureHelpItems> Microsoft.CodeAnalysis.SignatureHelp.AbstractSignatureHelpProvider.GetItemsAsync(Document document, int position, SignatureHelpTriggerInfo triggerInfo, SignatureHelpOptions options, CancellationToken cancellationToken)
   at async Task<(ISignatureHelpProvider provider, SignatureHelpItems items)> Microsoft.CodeAnalysis.Editor.Implementation.IntelliSense.SignatureHelp.Controller+Session.ComputeItemsAsync(ImmutableArray<ISignatureHelpProvider> providers, SnapshotPoint caretPosition, SignatureHelpTriggerInfo triggerInfo, SignatureHelpOptions options, Document document, CancellationToken cancellationToken) in C:/Roslyn/src/EditorFeatures/Core.Wpf/SignatureHelp/Controller.Session_ComputeModel.cs:line 197

[KirillOsenkov]

P.S. You need to do this under debugger because there are no user-visible symptoms as far as I can see.

[qgindi]

How VSCode responds to this exception: it does not show the parameter info UI.

How Visual Studio responds to this exception: the "Parameter info" feature stops working everywhere, until restarting. Tested with VS Community 2022 Preview Version 17.11.0 Preview 4.0.

[CyrusNajmabadi]

Investigating.