Fix formatting incorrect for void tag helpers by Copilot · Pull Request #12802 · dotnet/razor

Copilot · 2026-02-19T23:14:06Z

Summary of the changes

Void tag helpers (e.g., <input asp-for="AllowAuthorizationCodeFlow">) caused indentation to increase with each occurrence because CSharpDocumentGenerator.ElementCausesIndentation only recognized MarkupStartTagSyntax (plain HTML) as void — not MarkupTagHelperStartTagSyntax. This caused an unmatched { /* */ to be emitted in the generated C# document with no corresponding }, since void elements have no end tag.

BaseMarkupStartTagSyntax: Moved IsVoidElement() up from MarkupStartTagSyntax so both plain HTML and tag helper start tags inherit it
MarkupStartTagSyntax: Removed now-redundant IsVoidElement() override
CSharpDocumentGenerator.ElementCausesIndentation: Replaced type-checked node is MarkupStartTagSyntax startTag && startTag.IsVoidElement() with node.IsVoidElement() — fixing the unmatched brace emission for void tag helpers
Tests: Added VoidTagHelpers_NotIndented to HtmlFormattingTest in the VS Code shared formatting test project

Original prompt

This section details on the original issue you should resolve

<issue_title>Formatting incorrect for void tag helpers</issue_title>
<issue_description>Create a cshtml document with the following and then format:
<input type="checkbox">
<input type="checkbox">
<input type="checkbox">
<input type="checkbox">
<input type="checkbox">

<input type="checkbox" asp-for="AllowAuthorizationCodeFlow">
<input type="checkbox" asp-for="AllowAuthorizationCodeFlow">
<input type="checkbox" asp-for="AllowAuthorizationCodeFlow">
<input type="checkbox" asp-for="AllowAuthorizationCodeFlow">
<input type="checkbox" asp-for="AllowAuthorizationCodeFlow">
Expected: All indented to the same level
Actual: One the void tagHelpers are encountered, the indentation starts increasing.</issue_description>

Comments on the Issue (you are @copilot in this section)
@davidwengier You know, I've been wondering how copilot will go with formatting, now that all of the tests are shared and cross-platform. Let's find out!

Fixes Formatting incorrect for void tag helpers #12801

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.

…lass and fixing CSharpDocumentGenerator and FormattingVisitor Co-authored-by: davidwengier <754264+davidwengier@users.noreply.github.com>

Co-authored-by: davidwengier <754264+davidwengier@users.noreply.github.com>

Copilot · 2026-02-19T23:54:37Z

Just as a heads up, I was blocked by some firewall rules while working on your feedback. Expand below for details.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

vb4vsblobprodcus33.vsblob.vsassets.io
- Triggering command: /usr/share/dotnet/dotnet dotnet test src/Razor/test/Microsoft.AspNetCore.Razor.LanguageServer.Test/Microsoft.AspNetCore.Razor.LanguageServer.Test.csproj --filter FullyQualifiedName~VoidTagHelpers -v minimal (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

Configure Actions setup steps to set up my environment, which run before the firewall is enabled
Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Co-authored-by: davidwengier <754264+davidwengier@users.noreply.github.com>

Copilot · 2026-02-19T23:58:39Z

Just as a heads up, I was blocked by some firewall rules while working on your feedback. Expand below for details.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

vb4vsblobprodcus33.vsblob.vsassets.io
- Triggering command: /usr/share/dotnet/dotnet dotnet test src/Razor/test/Microsoft.VisualStudioCode.RazorExtension.Test/Microsoft.VisualStudioCode.RazorExtension.Test.csproj --filter FullyQualifiedName~VoidTagHelpers -v minimal (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

Configure Actions setup steps to set up my environment, which run before the firewall is enabled
Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

davidwengier

LGTM

Initial plan

55efcb3

Copilot AI assigned Copilot and davidwengier Feb 19, 2026

Copilot started work on behalf of davidwengier February 19, 2026 23:14 View session

Fix formatting for void tag helpers by moving IsVoidElement to base c…

4c15529

…lass and fixing CSharpDocumentGenerator and FormattingVisitor Co-authored-by: davidwengier <754264+davidwengier@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] Fix formatting issue for void tag helpers~~ Fix formatting incorrect for void tag helpers Feb 19, 2026

Copilot AI requested a review from davidwengier February 19, 2026 23:41

Copilot finished work on behalf of davidwengier February 19, 2026 23:41

davidwengier reviewed Feb 19, 2026

View reviewed changes

Comment thread src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Formatting/FormattingVisitor.cs

Copilot started work on behalf of davidwengier February 19, 2026 23:50 View session

davidwengier reviewed Feb 19, 2026

View reviewed changes

Comment thread src/Razor/test/Microsoft.AspNetCore.Razor.LanguageServer.Test/Formatting/HtmlFormattingTest.cs

Revert changes to FormattingVisitor.cs

04f420c

Co-authored-by: davidwengier <754264+davidwengier@users.noreply.github.com>

Copilot AI requested a review from davidwengier February 19, 2026 23:54

Copilot finished work on behalf of davidwengier February 19, 2026 23:54

Copilot started work on behalf of davidwengier February 19, 2026 23:55 View session

Revert changes to LanguageServer HtmlFormattingTest.cs

eb294aa

Co-authored-by: davidwengier <754264+davidwengier@users.noreply.github.com>

Copilot finished work on behalf of davidwengier February 19, 2026 23:58

davidwengier approved these changes Feb 20, 2026

View reviewed changes

davidwengier marked this pull request as ready for review February 20, 2026 00:14

davidwengier requested a review from a team as a code owner February 20, 2026 00:14

chsienki approved these changes Feb 20, 2026

View reviewed changes

davidwengier merged commit 16a87c5 into main Feb 21, 2026
10 checks passed

davidwengier deleted the copilot/fix-void-tag-helpers-formatting branch February 21, 2026 02:38

dotnet-policy-service bot added this to the Next milestone Feb 21, 2026

This was referenced Feb 21, 2026

[release/11.0.1xx-preview2] Source code updates from dotnet/razor dotnet/dotnet#5027

Merged

[main] Source code updates from dotnet/razor dotnet/dotnet#5030

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davidwengier mentioned this pull request Feb 22, 2026

Bump Razor to 10.0.0-preview.26121.1 dotnet/vscode-csharp#9025

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akhera99 removed this from the Next milestone Feb 24, 2026

akhera99 added this to the 18.5 milestone Feb 24, 2026

dotnet-bot mentioned this pull request Feb 24, 2026

[Automated] PRs inserted in VS build main-11523.59 #12817

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davidwengier mentioned this pull request Mar 18, 2026

HTML code indentation in Blazor is not working properly #12914

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davidwengier linked an issue Mar 18, 2026 that may be closed by this pull request

HTML code indentation in Blazor is not working properly #12914

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Fix formatting incorrect for void tag helpers#12802

Fix formatting incorrect for void tag helpers#12802
davidwengier merged 4 commits intomainfrom
copilot/fix-void-tag-helpers-formatting

Copilot AI commented Feb 19, 2026 •

edited

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Copilot AI commented Feb 19, 2026

I tried to connect to the following addresses, but was blocked by firewall rules:

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Copilot AI commented Feb 19, 2026

I tried to connect to the following addresses, but was blocked by firewall rules:

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Copilot AI commented Feb 19, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Summary of the changes

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Copilot AI commented Feb 19, 2026

I tried to connect to the following addresses, but was blocked by firewall rules:

Uh oh!

Copilot AI commented Feb 19, 2026

I tried to connect to the following addresses, but was blocked by firewall rules:

Uh oh!

davidwengier left a comment

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Copilot AI commented Feb 19, 2026 •

edited

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