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[release/stable] Resolve consecutive WithoutEndTag tag helpers as siblings #84782

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chsienki merged 2 commits into from
Aug 10, 2026
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[release/stable] Resolve consecutive WithoutEndTag tag helpers as siblings #84782

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3a1e17f
Resolve consecutive WithoutEndTag tag helpers as siblings (#84771)
chsienki Aug 6, 2026
5eb281a
Restore using directives dropped during backport
chsienki Aug 7, 2026
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240 changes: 238 additions & 2 deletions ...er/Microsoft.AspNetCore.Razor.Language/test/IntegrationTests/TagHelpersIntegrationTest.cs
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Expand Up @@ -5,7 +5,9 @@
using System.Collections.Immutable;
using System.Collections.Generic;
using System.Linq;
using Microsoft.AspNetCore.Razor.Language.Intermediate;
using Microsoft.AspNetCore.Razor.Language.Syntax;
using Roslyn.Test.Utilities;
using Xunit;

namespace Microsoft.AspNetCore.Razor.Language.IntegrationTests;
Expand Down Expand Up @@ -181,11 +183,237 @@ public void AddTagHelperDirective_StoresDirectiveTagHelperContributions()
Assert.NotEmpty(contribution.ContributedTagHelpers);
}

[Fact]
[WorkItem("https://github.com/dotnet/aspnetcore/issues/68193")]
public void ConsecutiveWithoutEndTagTagHelpers_AllBind()
{
// The HTML parser nests consecutive unclosed tags (`<alpha><beta><gamma>` becomes
// alpha > beta > gamma). Each of these is a WithoutEndTag tag helper, so all three
// must still bind as siblings rather than only the first.
TagHelperCollection tagHelpers =
[
CreateTagHelperDescriptor(
tagName: "alpha",
typeName: "AlphaTagHelper",
assemblyName: "TestAssembly",
tagStructure: TagStructure.WithoutEndTag),
CreateTagHelperDescriptor(
tagName: "beta",
typeName: "BetaTagHelper",
assemblyName: "TestAssembly",
tagStructure: TagStructure.WithoutEndTag),
CreateTagHelperDescriptor(
tagName: "gamma",
typeName: "GammaTagHelper",
assemblyName: "TestAssembly",
tagStructure: TagStructure.WithoutEndTag),
];

var projectEngine = CreateProjectEngine(builder => builder.SetTagHelpers(tagHelpers));
var projectItem = AddProjectItemFromText("""
@addTagHelper *, TestAssembly
<head>
<alpha>
<beta>
<gamma>
</head>
""", filePath: "Index.cshtml");

// Act
var codeDocument = projectEngine.Process(projectItem);

// Assert
var documentNode = codeDocument.GetRequiredDocumentNode();
var tagHelperNodes = documentNode.FindDescendantNodes<TagHelperIntermediateNode>();
Assert.Collection(tagHelperNodes,
node => Assert.Equal("alpha", node.TagName),
node => Assert.Equal("beta", node.TagName),
node => Assert.Equal("gamma", node.TagName));

// They are siblings, not nested: each WithoutEndTag helper promoted its body out, so
// none of them contains another tag helper.
Assert.All(tagHelperNodes, node => Assert.Empty(node.FindDescendantNodes<TagHelperIntermediateNode>()));
}

[Fact]
[WorkItem("https://github.com/dotnet/aspnetcore/issues/68193")]
public void MixedNestedStartTagOnlyAndHtmlTagHelpers_AllResolveCorrectly()
{
// A deliberately tangled mix: a nestable tag helper (wrapper) containing consecutive
// WithoutEndTag helpers (alpha, beta) and a normal one (bold), followed by a second
// WithoutEndTag helper whose parser-nested body wraps a real HTML element (<div>) and
// yet another WithoutEndTag helper. Every tag helper must bind, real HTML (<section>,
// <div>) must stay markup, and document order must be preserved.
// Note: custom (non-void) tag names are required -- the HTML parser self-terminates
// real void elements like <input>/<br>, which wouldn't exercise the nesting-promotion path.
TagHelperCollection tagHelpers =
[
CreateTagHelperDescriptor(
tagName: "wrapper",
typeName: "WrapperTagHelper",
assemblyName: "TestAssembly"),
CreateTagHelperDescriptor(
tagName: "bold",
typeName: "BoldTagHelper",
assemblyName: "TestAssembly"),
CreateTagHelperDescriptor(
tagName: "alpha",
typeName: "AlphaTagHelper",
assemblyName: "TestAssembly",
tagStructure: TagStructure.WithoutEndTag),
CreateTagHelperDescriptor(
tagName: "beta",
typeName: "BetaTagHelper",
assemblyName: "TestAssembly",
tagStructure: TagStructure.WithoutEndTag),
];

var projectEngine = CreateProjectEngine(builder => builder.SetTagHelpers(tagHelpers));
var projectItem = AddProjectItemFromText("""
@addTagHelper *, TestAssembly
<section>
<wrapper>
<alpha>
<beta>
<bold>text</bold>
</wrapper>
<alpha>
<div>plain html</div>
<beta>
</section>
""", filePath: "Index.cshtml");

// Act
var codeDocument = projectEngine.Process(projectItem);

// Assert: every tag helper binds, in document order, with the WithoutEndTag helpers
// promoted to siblings rather than swallowing what follows them.
var documentNode = codeDocument.GetRequiredDocumentNode();
var tagHelperNodes = documentNode.FindDescendantNodes<TagHelperIntermediateNode>();
Assert.Collection(tagHelperNodes,
node => Assert.Equal("wrapper", node.TagName),
node => Assert.Equal("alpha", node.TagName),
node => Assert.Equal("beta", node.TagName),
node => Assert.Equal("bold", node.TagName),
node => Assert.Equal("alpha", node.TagName),
node => Assert.Equal("beta", node.TagName));

// Structure: wrapper genuinely contains alpha/beta/bold, while the WithoutEndTag helpers
// stay flat -- their bodies were promoted out, so none nests another tag helper.
Assert.Collection(tagHelperNodes[0].FindDescendantNodes<TagHelperIntermediateNode>(),
node => Assert.Equal("alpha", node.TagName),
node => Assert.Equal("beta", node.TagName),
node => Assert.Equal("bold", node.TagName));
Assert.Empty(tagHelperNodes[1].FindDescendantNodes<TagHelperIntermediateNode>()); // alpha inside wrapper
Assert.Empty(tagHelperNodes[2].FindDescendantNodes<TagHelperIntermediateNode>()); // beta inside wrapper
Assert.Empty(tagHelperNodes[4].FindDescendantNodes<TagHelperIntermediateNode>()); // alpha at top level
Assert.Empty(tagHelperNodes[5].FindDescendantNodes<TagHelperIntermediateNode>()); // beta at top level

// The real HTML elements must survive as literal markup, never bound as tag helpers.
var generatedCode = codeDocument.GetRequiredCSharpDocument().Text.ToString();
Assert.Contains("<section>", generatedCode);
Assert.Contains("<div>", generatedCode);
Assert.Contains("plain html", generatedCode);
}

[Fact]
[WorkItem("https://github.com/dotnet/aspnetcore/issues/68193")]
public void PromotedStartTagOnlySibling_BindsUsingParentTagHelperContext()
{
// `child` is a WithoutEndTag helper that only matches when its parent is `wrapper`. The
// parser nests it under the preceding WithoutEndTag helper `lead` (<lead><child>), so it
// is reached only after `lead` promotes it to a sibling inside wrapper's body. That
// re-resolution must carry wrapper as the parent-tag context, otherwise the
// RequireParentTag("wrapper") rule can't match and `child` silently fails to bind.
TagHelperCollection tagHelpers =
[
CreateTagHelperDescriptor(
tagName: "wrapper",
typeName: "WrapperTagHelper",
assemblyName: "TestAssembly"),
CreateTagHelperDescriptor(
tagName: "lead",
typeName: "LeadTagHelper",
assemblyName: "TestAssembly",
tagStructure: TagStructure.WithoutEndTag),
CreateTagHelperDescriptor(
tagName: "child",
typeName: "ChildTagHelper",
assemblyName: "TestAssembly",
tagStructure: TagStructure.WithoutEndTag,
parentTag: "wrapper"),
];

var projectEngine = CreateProjectEngine(builder => builder.SetTagHelpers(tagHelpers));
var projectItem = AddProjectItemFromText("""
@addTagHelper *, TestAssembly
<wrapper>
<lead>
<child>
</wrapper>
""", filePath: "Index.cshtml");

// Act
var codeDocument = projectEngine.Process(projectItem);

// Assert: child binds because the promoted sibling was resolved with wrapper as its
// parent-tag context.
var documentNode = codeDocument.GetRequiredDocumentNode();
var tagHelperNodes = documentNode.FindDescendantNodes<TagHelperIntermediateNode>();
Assert.Collection(tagHelperNodes,
node => Assert.Equal("wrapper", node.TagName),
node => Assert.Equal("lead", node.TagName),
node => Assert.Equal("child", node.TagName));
}

[Fact]
[WorkItem("https://github.com/dotnet/aspnetcore/issues/68193")]
public void PromotedWithoutEndTagTagHelpers_Baseline()
{
// Full-IR structural baseline for the promotion scenario: a nestable helper containing
// consecutive WithoutEndTag helpers plus a normal one, followed by a second WithoutEndTag
// helper whose parser-nested body wraps real HTML and another helper. The .ir.txt baseline
// captures the exact tree shape, proving the promoted helpers become siblings (not nested)
// and that the real HTML survives as markup.
TagHelperCollection tagHelpers =
[
CreateTagHelperDescriptor(
tagName: "wrapper",
typeName: "WrapperTagHelper",
assemblyName: "TestAssembly"),
CreateTagHelperDescriptor(
tagName: "bold",
typeName: "BoldTagHelper",
assemblyName: "TestAssembly"),
CreateTagHelperDescriptor(
tagName: "alpha",
typeName: "AlphaTagHelper",
assemblyName: "TestAssembly",
tagStructure: TagStructure.WithoutEndTag),
CreateTagHelperDescriptor(
tagName: "beta",
typeName: "BetaTagHelper",
assemblyName: "TestAssembly",
tagStructure: TagStructure.WithoutEndTag),
];

var projectEngine = CreateProjectEngine(builder => builder.SetTagHelpers(tagHelpers));
var projectItem = CreateProjectItemFromFile();

// Act
var codeDocument = projectEngine.Process(projectItem);

// Assert
AssertDocumentNodeMatchesBaseline(codeDocument.GetRequiredDocumentNode());
}

private static TagHelperDescriptor CreateTagHelperDescriptor(
string tagName,
string typeName,
string assemblyName,
IEnumerable<Action<BoundAttributeDescriptorBuilder>>? attributes = null)
IEnumerable<Action<BoundAttributeDescriptorBuilder>>? attributes = null,
TagStructure tagStructure = TagStructure.Unspecified,
string? parentTag = null)
{
var builder = TagHelperDescriptorBuilder.CreateTagHelper(typeName, assemblyName);
builder.SetTypeName(typeName, typeNamespace: null, typeNameIdentifier: null);
Expand All @@ -198,7 +426,15 @@ private static TagHelperDescriptor CreateTagHelperDescriptor(
}
}

builder.TagMatchingRuleDescriptor(ruleBuilder => ruleBuilder.RequireTagName(tagName));
builder.TagMatchingRuleDescriptor(ruleBuilder =>
{
ruleBuilder.RequireTagName(tagName).RequireTagStructure(tagStructure);

if (parentTag != null)
{
ruleBuilder.RequireParentTag(parentTag);
}
});

var descriptor = builder.Build();

Expand Down
11 changes: 11 additions & 0 deletions ...ntegrationTests/TagHelpersIntegrationTest/PromotedWithoutEndTagTagHelpers_Baseline.cshtml
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Original file line number Diff line number Diff line change
@@ -0,0 +1,11 @@
@addTagHelper *, TestAssembly
<section>
<wrapper>
<alpha>
<beta>
<bold>text</bold>
</wrapper>
<alpha>
<div>plain html</div>
<beta>
</section>
63 changes: 63 additions & 0 deletions ...ntegrationTests/TagHelpersIntegrationTest/PromotedWithoutEndTagTagHelpers_Baseline.ir.txt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,63 @@
Document -
RazorCompiledItemAttribute -
NamespaceDeclaration - - Razor
RazorSourceChecksumAttribute -
ClassDeclaration - - public - Template - -
DefaultTagHelperRuntime -
FieldDeclaration - - private - global::WrapperTagHelper - __WrapperTagHelper
FieldDeclaration - - private - global::AlphaTagHelper - __AlphaTagHelper
FieldDeclaration - - private - global::BetaTagHelper - __BetaTagHelper
FieldDeclaration - - private - global::BoldTagHelper - __BoldTagHelper
MethodDeclaration - - public async override - global::System.Threading.Tasks.Task - ExecuteAsync
HtmlContent - (31:1,0 [11] PromotedWithoutEndTagTagHelpers_Baseline.cshtml)
LazyIntermediateToken - (31:1,0 [8] PromotedWithoutEndTagTagHelpers_Baseline.cshtml) - Html - <section
LazyIntermediateToken - (39:1,8 [1] PromotedWithoutEndTagTagHelpers_Baseline.cshtml) - Html - >
LazyIntermediateToken - (40:1,9 [2] PromotedWithoutEndTagTagHelpers_Baseline.cshtml) - Html - \n
TagHelper - (42:2,0 [57] PromotedWithoutEndTagTagHelpers_Baseline.cshtml) - wrapper - TagMode.StartTagAndEndTag
DefaultTagHelperBody -
HtmlContent - (51:2,9 [2] PromotedWithoutEndTagTagHelpers_Baseline.cshtml)
LazyIntermediateToken - (51:2,9 [2] PromotedWithoutEndTagTagHelpers_Baseline.cshtml) - Html - \n
TagHelper - (53:3,0 [36] PromotedWithoutEndTagTagHelpers_Baseline.cshtml) - alpha - TagMode.StartTagOnly
DefaultTagHelperBody -
DefaultTagHelperCreate - - AlphaTagHelper
DefaultTagHelperExecute -
HtmlContent - (60:3,7 [2] PromotedWithoutEndTagTagHelpers_Baseline.cshtml)
LazyIntermediateToken - (60:3,7 [2] PromotedWithoutEndTagTagHelpers_Baseline.cshtml) - Html - \n
TagHelper - (62:4,0 [27] PromotedWithoutEndTagTagHelpers_Baseline.cshtml) - beta - TagMode.StartTagOnly
DefaultTagHelperBody -
DefaultTagHelperCreate - - BetaTagHelper
DefaultTagHelperExecute -
HtmlContent - (68:4,6 [2] PromotedWithoutEndTagTagHelpers_Baseline.cshtml)
LazyIntermediateToken - (68:4,6 [2] PromotedWithoutEndTagTagHelpers_Baseline.cshtml) - Html - \n
TagHelper - (70:5,0 [17] PromotedWithoutEndTagTagHelpers_Baseline.cshtml) - bold - TagMode.StartTagAndEndTag
DefaultTagHelperBody -
HtmlContent - (76:5,6 [4] PromotedWithoutEndTagTagHelpers_Baseline.cshtml)
LazyIntermediateToken - (76:5,6 [4] PromotedWithoutEndTagTagHelpers_Baseline.cshtml) - Html - text
DefaultTagHelperCreate - - BoldTagHelper
DefaultTagHelperExecute -
HtmlContent - (87:5,17 [2] PromotedWithoutEndTagTagHelpers_Baseline.cshtml)
LazyIntermediateToken - (87:5,17 [2] PromotedWithoutEndTagTagHelpers_Baseline.cshtml) - Html - \n
DefaultTagHelperCreate - - WrapperTagHelper
DefaultTagHelperExecute -
HtmlContent - (99:6,10 [2] PromotedWithoutEndTagTagHelpers_Baseline.cshtml)
LazyIntermediateToken - (99:6,10 [2] PromotedWithoutEndTagTagHelpers_Baseline.cshtml) - Html - \n
TagHelper - (101:7,0 [40] PromotedWithoutEndTagTagHelpers_Baseline.cshtml) - alpha - TagMode.StartTagOnly
DefaultTagHelperBody -
DefaultTagHelperCreate - - AlphaTagHelper
DefaultTagHelperExecute -
HtmlContent - (108:7,7 [25] PromotedWithoutEndTagTagHelpers_Baseline.cshtml)
LazyIntermediateToken - (108:7,7 [2] PromotedWithoutEndTagTagHelpers_Baseline.cshtml) - Html - \n
LazyIntermediateToken - (110:8,0 [4] PromotedWithoutEndTagTagHelpers_Baseline.cshtml) - Html - <div
LazyIntermediateToken - (114:8,4 [1] PromotedWithoutEndTagTagHelpers_Baseline.cshtml) - Html - >
LazyIntermediateToken - (115:8,5 [10] PromotedWithoutEndTagTagHelpers_Baseline.cshtml) - Html - plain html
LazyIntermediateToken - (125:8,15 [6] PromotedWithoutEndTagTagHelpers_Baseline.cshtml) - Html - </div>
LazyIntermediateToken - (131:8,21 [2] PromotedWithoutEndTagTagHelpers_Baseline.cshtml) - Html - \n
TagHelper - (133:9,0 [8] PromotedWithoutEndTagTagHelpers_Baseline.cshtml) - beta - TagMode.StartTagOnly
DefaultTagHelperBody -
DefaultTagHelperCreate - - BetaTagHelper
DefaultTagHelperExecute -
HtmlContent - (139:9,6 [2] PromotedWithoutEndTagTagHelpers_Baseline.cshtml)
LazyIntermediateToken - (139:9,6 [2] PromotedWithoutEndTagTagHelpers_Baseline.cshtml) - Html - \n
HtmlContent - (141:10,0 [12] PromotedWithoutEndTagTagHelpers_Baseline.cshtml)
LazyIntermediateToken - (141:10,0 [10] PromotedWithoutEndTagTagHelpers_Baseline.cshtml) - Html - </section>
LazyIntermediateToken - (151:10,10 [2] PromotedWithoutEndTagTagHelpers_Baseline.cshtml) - Html - \n
25 changes: 25 additions & 0 deletions ...ler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/DefaultTagHelperResolutionPhase.cs
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Expand Up @@ -197,6 +197,31 @@ private void ResolveElement(
{
parent.Children.Insert(insertIdx++, elementNode.Children[i]);
}

// The promoted nodes were parsed as body children of this element because the
// HTML parser nests unclosed tags (e.g. `<a><b><c>` becomes a > b > c). Now that
// this element is bound as StartTagOnly, they are siblings that may themselves be
// tag helpers. The outer walker iterates in reverse and won't revisit these
// newly inserted positions, so resolve them here (in reverse, since resolving a
// promoted StartTagOnly sibling can insert further siblings after it).
for (var j = insertIdx - 1; j > index; j--)
{
if (j < parent.Children.Count)
{
if (parent.Children[j] is UnresolvedElementIntermediateNode promotedElement)
{
// Forward tagHelperParent: the promoted siblings live in the same
// container as this StartTagOnly element, so they share its parent-tag
// context. Dropping it would break bindings that depend on the parent
// (e.g. RequireParentTag or component child-content matching).
ResolveElement(parent, j, promotedElement, binder, prefix, usedHelpers, in context, tagHelperParent);
}
else
{
ResolveElements(parent.Children[j], binder, prefix, usedHelpers, in context);
}
}
}
}
}
}
Expand Down