Code snippets whose shortcuts start with # cannot be used

[vsfeedback]

This issue has been moved from a ticket on Developer Community.

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[severity:It's more difficult to complete my work]
I've just updated VS2019 to ver. 16.10.1 and all my code snippets whose shortcuts start with '#' (hash sign) cannot be used.

Steps to reproduce:

1. Create a code snippet (for C# in my case) and give it a shortcut '#abc'
2. Start editing a C# file
3. Type '#abc' and press Tab twice

Expected behaviour:
The code snipped should be inserted.

Actual behaviour:
The '#abc' text stays on the screen and two tabs are inserted afterwards.

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Original Comments

Feedback Bot on 6/10/2021, 06:48 PM:

We have directed your feedback to the appropriate engineering team for further evaluation. The team will review the feedback and notify you about the next steps.

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Original Solutions

(no solutions)

[RaceRalph]

It's a regression. Shortcuts starting with '#' were working in all versions of VS2019 preceding 16.10.

[sharwell]

📝 This behavior only occurs when Argument Completion is enabled. The error is caused by this code failing to handle the case where token.Kind == None:

roslyn/src/VisualStudio/Core/Def/Implementation/Snippets/AbstractSnippetExpansionClient.cs

Lines 741 to 742 in 781dab8

	var token = await semanticModel.SyntaxTree.GetTouchingWordAsync(caretPosition.Position, document.GetRequiredLanguageService<ISyntaxFactsService>(), cancellationToken).ConfigureAwait(false);
	var semanticInfo = semanticModel.GetSemanticInfo(token, document.Project.Solution.Workspace, cancellationToken);