From 9fe760218a00a0cb4bdb0088b802b3b0a52af8a5 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 11 Nov 2025 23:07:22 +0000
Subject: [PATCH 1/3] Initial plan


From c8a4e637465107e8ffd5a986297cdbd4bc2c8659 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 11 Nov 2025 23:33:41 +0000
Subject: [PATCH 2/3] Fix @section directive to only be legal in .cshtml files

- Modified SectionDirective.cs to only register for RazorFileKind.Legacy
- Added tests to verify section directive works in .cshtml but not in .razor files

Co-authored-by: chsienki <16246502+chsienki@users.noreply.github.com>
---
 .../Extensions/SectionDirectivePassTest.cs    | 44 +++++++++++++++++++
 .../test/Legacy/CSharpSectionTest.cs          |  1 -
 .../Language/Extensions/SectionDirective.cs   |  2 +-
 3 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/Extensions/SectionDirectivePassTest.cs b/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/Extensions/SectionDirectivePassTest.cs
index a50302a5802..2d149e5702f 100644
--- a/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/Extensions/SectionDirectivePassTest.cs
+++ b/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/Extensions/SectionDirectivePassTest.cs
@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Linq;
 using Microsoft.AspNetCore.Razor.Language.Intermediate;
 using Xunit;
 using static Microsoft.AspNetCore.Razor.Language.Intermediate.IntermediateNodeAssert;
@@ -76,4 +77,47 @@ public void Execute_WrapsStatementInSectionNode()
         Assert.Equal("Header", section.SectionName);
         Children(section, c => Html(" <p>Hello World</p> ", c));
     }
+
+    [Fact]
+    public void SectionDirective_IsRecognizedInLegacyFiles()
+    {
+        // Arrange
+        var content = "@section Header { <p>Hello World</p> }";
+        var source = TestRazorSourceDocument.Create(content, filePath: "test.cshtml", relativePath: "test.cshtml");
+        
+        // Act
+        var codeDocument = ProjectEngine.CreateCodeDocument(source, RazorFileKind.Legacy);
+        ProjectEngine.Engine.Process(codeDocument);
+
+        // Assert
+        var syntaxTree = codeDocument.GetSyntaxTree();
+        Assert.NotNull(syntaxTree);
+        
+        // The section directive should be recognized without errors
+        var diagnostics = syntaxTree.Diagnostics;
+        Assert.Empty(diagnostics);
+    }
+
+    [Fact]
+    public void SectionDirective_IsNotRecognizedInComponentFiles()
+    {
+        // Arrange
+        var content = "@section Header { <p>Hello World</p> }";
+        var source = TestRazorSourceDocument.Create(content, filePath: "test.razor", relativePath: "test.razor");
+        
+        // Act
+        var codeDocument = ProjectEngine.CreateCodeDocument(source, RazorFileKind.Component);
+        ProjectEngine.Engine.Process(codeDocument);
+
+        // Assert
+        var syntaxTree = codeDocument.GetSyntaxTree();
+        Assert.NotNull(syntaxTree);
+        
+        // The section directive should NOT be recognized in component files.
+        // Verify that no RazorDirective node for 'section' exists in the syntax tree
+        var directiveNodes = syntaxTree.Root.DescendantNodes()
+            .OfType<Microsoft.AspNetCore.Razor.Language.Syntax.RazorDirectiveSyntax>();
+        
+        Assert.DoesNotContain(directiveNodes, d => d.DirectiveDescriptor?.Directive == "section");
+    }
 }
diff --git a/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/Legacy/CSharpSectionTest.cs b/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/Legacy/CSharpSectionTest.cs
index be35c04c2d3..8f1345d3b75 100644
--- a/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/Legacy/CSharpSectionTest.cs
+++ b/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/Legacy/CSharpSectionTest.cs
@@ -300,5 +300,4 @@ public void _WithDoubleTransition2()
     {
         ParseDocumentTest("@section s {<span foo='@DateTime.Now @@' />}", [SectionDirective.Directive]);
     }
-
 }
diff --git a/src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/Extensions/SectionDirective.cs b/src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/Extensions/SectionDirective.cs
index 8a078b433bc..4636c8b2d55 100644
--- a/src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/Extensions/SectionDirective.cs
+++ b/src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/Extensions/SectionDirective.cs
@@ -26,7 +26,7 @@ public static void Register(RazorProjectEngineBuilder builder)
             throw new ArgumentNullException(nameof(builder));
         }
 
-        builder.AddDirective(Directive, RazorFileKind.Legacy, RazorFileKind.Component);
+        builder.AddDirective(Directive, RazorFileKind.Legacy);
         builder.Features.Add(new SectionDirectivePass());
         builder.AddTargetExtension(new SectionTargetExtension());
     }

From 985a0a4957af4d594e2e8c65ded02a76707b01ed Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Wed, 12 Nov 2025 05:34:52 +0000
Subject: [PATCH 3/3] Add compiler integration test for @section directive in
 components

Added SectionDirective_NotAllowed integration test to verify code generation when @section is used in .razor files. The test confirms that @section is no longer recognized as a directive and is instead treated as regular content, preventing compilation errors.

Co-authored-by: davidwengier <754264+davidwengier@users.noreply.github.com>
---
 .../ComponentCodeGenerationTestBase.cs        | 16 +++++++
 .../TestComponent.codegen.cs                  | 45 +++++++++++++++++++
 .../TestComponent.ir.txt                      | 27 +++++++++++
 .../TestComponent.mappings.txt                | 10 +++++
 .../TestComponent.codegen.cs                  | 42 +++++++++++++++++
 .../TestComponent.ir.txt                      | 16 +++++++
 .../TestComponent.mappings.txt                | 10 +++++
 7 files changed, 166 insertions(+)
 create mode 100644 src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/SectionDirective_NotAllowed/TestComponent.codegen.cs
 create mode 100644 src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/SectionDirective_NotAllowed/TestComponent.ir.txt
 create mode 100644 src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/SectionDirective_NotAllowed/TestComponent.mappings.txt
 create mode 100644 src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/SectionDirective_NotAllowed/TestComponent.codegen.cs
 create mode 100644 src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/SectionDirective_NotAllowed/TestComponent.ir.txt
 create mode 100644 src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/SectionDirective_NotAllowed/TestComponent.mappings.txt

diff --git a/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/IntegrationTests/ComponentCodeGenerationTestBase.cs b/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/IntegrationTests/ComponentCodeGenerationTestBase.cs
index 3f328189d33..577bb12c14c 100644
--- a/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/IntegrationTests/ComponentCodeGenerationTestBase.cs
+++ b/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/IntegrationTests/ComponentCodeGenerationTestBase.cs
@@ -12968,5 +12968,21 @@ @inject float Value5
         CompileToAssembly(generated);
     }
 
+    [IntegrationTestFact, WorkItem("https://github.com/dotnet/razor/issues/11273")]
+    public void SectionDirective_NotAllowed()
+    {
+        // Verify that @section is not recognized in components and produces appropriate code-gen
+        // Act
+        var generated = CompileToCSharp("""
+            @{ var section = "Section"; }
+            @section One { <p>Content</p> }
+            """);
+
+        // Assert
+        AssertDocumentNodeMatchesBaseline(generated.CodeDocument);
+        AssertCSharpDocumentMatchesBaseline(generated.CodeDocument);
+        CompileToAssembly(generated);
+    }
+
     #endregion
 }
diff --git a/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/SectionDirective_NotAllowed/TestComponent.codegen.cs b/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/SectionDirective_NotAllowed/TestComponent.codegen.cs
new file mode 100644
index 00000000000..04a0de9e6dc
--- /dev/null
+++ b/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/SectionDirective_NotAllowed/TestComponent.codegen.cs
@@ -0,0 +1,45 @@
+// <auto-generated/>
+#pragma warning disable 1591
+namespace Test
+{
+    #line default
+    using global::System;
+    using global::System.Collections.Generic;
+    using global::System.Linq;
+    using global::System.Threading.Tasks;
+    using global::Microsoft.AspNetCore.Components;
+    #line default
+    #line hidden
+    #nullable restore
+    public partial class TestComponent : global::Microsoft.AspNetCore.Components.ComponentBase
+    #nullable disable
+    {
+        #pragma warning disable 219
+        private void __RazorDirectiveTokenHelpers__() {
+        }
+        #pragma warning restore 219
+        #pragma warning disable 0414
+        private static object __o = null;
+        #pragma warning restore 0414
+        #pragma warning disable 1998
+        protected override void BuildRenderTree(global::Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder __builder)
+        {
+#nullable restore
+#line 1 "x:\dir\subdir\Test\TestComponent.cshtml"
+   var section = "Section"; 
+
+#line default
+#line hidden
+#nullable disable
+#nullable restore
+#line 2 "x:\dir\subdir\Test\TestComponent.cshtml"
+__o = section;
+
+#line default
+#line hidden
+#nullable disable
+        }
+        #pragma warning restore 1998
+    }
+}
+#pragma warning restore 1591
diff --git a/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/SectionDirective_NotAllowed/TestComponent.ir.txt b/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/SectionDirective_NotAllowed/TestComponent.ir.txt
new file mode 100644
index 00000000000..2546d98f9e3
--- /dev/null
+++ b/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/SectionDirective_NotAllowed/TestComponent.ir.txt
@@ -0,0 +1,27 @@
+Document - 
+    NamespaceDeclaration -  - Test
+        UsingDirective - (3:1,1 [20] ) - global::System
+        UsingDirective - (26:2,1 [40] ) - global::System.Collections.Generic
+        UsingDirective - (69:3,1 [25] ) - global::System.Linq
+        UsingDirective - (97:4,1 [36] ) - global::System.Threading.Tasks
+        UsingDirective - (136:5,1 [45] ) - global::Microsoft.AspNetCore.Components
+        ClassDeclaration -  - public partial - TestComponent - global::Microsoft.AspNetCore.Components.ComponentBase - 
+            DesignTimeDirective - 
+            CSharpCode - 
+                IntermediateToken -  - CSharp - #pragma warning disable 0414
+            CSharpCode - 
+                IntermediateToken -  - CSharp - private static object __o = null;
+            CSharpCode - 
+                IntermediateToken -  - CSharp - #pragma warning restore 0414
+            MethodDeclaration -  - protected override - void - BuildRenderTree
+                CSharpCode - (2:0,2 [26] x:\dir\subdir\Test\TestComponent.cshtml)
+                    LazyIntermediateToken - (2:0,2 [26] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp -  var section = "Section"; 
+                CSharpExpression - (32:1,1 [7] x:\dir\subdir\Test\TestComponent.cshtml)
+                    LazyIntermediateToken - (32:1,1 [7] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - section
+                HtmlContent - (39:1,8 [7] x:\dir\subdir\Test\TestComponent.cshtml)
+                    LazyIntermediateToken - (39:1,8 [7] x:\dir\subdir\Test\TestComponent.cshtml) - Html -  One { 
+                MarkupElement - (46:1,15 [14] x:\dir\subdir\Test\TestComponent.cshtml) - p
+                    HtmlContent - (49:1,18 [7] x:\dir\subdir\Test\TestComponent.cshtml)
+                        LazyIntermediateToken - (49:1,18 [7] x:\dir\subdir\Test\TestComponent.cshtml) - Html - Content
+                HtmlContent - (60:1,29 [2] x:\dir\subdir\Test\TestComponent.cshtml)
+                    LazyIntermediateToken - (60:1,29 [2] x:\dir\subdir\Test\TestComponent.cshtml) - Html -  }
diff --git a/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/SectionDirective_NotAllowed/TestComponent.mappings.txt b/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/SectionDirective_NotAllowed/TestComponent.mappings.txt
new file mode 100644
index 00000000000..30f6624dbad
--- /dev/null
+++ b/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/SectionDirective_NotAllowed/TestComponent.mappings.txt
@@ -0,0 +1,10 @@
+Source Location: (2:0,2 [26] x:\dir\subdir\Test\TestComponent.cshtml)
+| var section = "Section"; |
+Generated Location: (987:28,2 [26] )
+| var section = "Section"; |
+
+Source Location: (32:1,1 [7] x:\dir\subdir\Test\TestComponent.cshtml)
+|section|
+Generated Location: (1141:35,6 [7] )
+|section|
+
diff --git a/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/SectionDirective_NotAllowed/TestComponent.codegen.cs b/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/SectionDirective_NotAllowed/TestComponent.codegen.cs
new file mode 100644
index 00000000000..1ee576f73ae
--- /dev/null
+++ b/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/SectionDirective_NotAllowed/TestComponent.codegen.cs
@@ -0,0 +1,42 @@
+// <auto-generated/>
+#pragma warning disable 1591
+namespace Test
+{
+    #line default
+    using global::System;
+    using global::System.Collections.Generic;
+    using global::System.Linq;
+    using global::System.Threading.Tasks;
+    using global::Microsoft.AspNetCore.Components;
+    #line default
+    #line hidden
+    #nullable restore
+    public partial class TestComponent : global::Microsoft.AspNetCore.Components.ComponentBase
+    #nullable disable
+    {
+        #pragma warning disable 1998
+        protected override void BuildRenderTree(global::Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder __builder)
+        {
+#nullable restore
+#line (1,3)-(1,29) "x:\dir\subdir\Test\TestComponent.cshtml"
+ var section = "Section"; 
+
+#line default
+#line hidden
+#nullable disable
+
+#nullable restore
+#line (2,2)-(2,9) 24 "x:\dir\subdir\Test\TestComponent.cshtml"
+__builder.AddContent(0, section
+
+#line default
+#line hidden
+#nullable disable
+            );
+            __builder.AddContent(1, " One { ");
+            __builder.AddMarkupContent(2, "<p>Content</p> }");
+        }
+        #pragma warning restore 1998
+    }
+}
+#pragma warning restore 1591
diff --git a/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/SectionDirective_NotAllowed/TestComponent.ir.txt b/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/SectionDirective_NotAllowed/TestComponent.ir.txt
new file mode 100644
index 00000000000..e964c486204
--- /dev/null
+++ b/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/SectionDirective_NotAllowed/TestComponent.ir.txt
@@ -0,0 +1,16 @@
+Document - 
+    NamespaceDeclaration -  - Test
+        UsingDirective - (3:1,1 [20] ) - global::System
+        UsingDirective - (26:2,1 [40] ) - global::System.Collections.Generic
+        UsingDirective - (69:3,1 [25] ) - global::System.Linq
+        UsingDirective - (97:4,1 [36] ) - global::System.Threading.Tasks
+        UsingDirective - (136:5,1 [45] ) - global::Microsoft.AspNetCore.Components
+        ClassDeclaration -  - public partial - TestComponent - global::Microsoft.AspNetCore.Components.ComponentBase - 
+            MethodDeclaration -  - protected override - void - BuildRenderTree
+                CSharpCode - (2:0,2 [26] x:\dir\subdir\Test\TestComponent.cshtml)
+                    LazyIntermediateToken - (2:0,2 [26] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp -  var section = "Section"; 
+                CSharpExpression - (32:1,1 [7] x:\dir\subdir\Test\TestComponent.cshtml)
+                    LazyIntermediateToken - (32:1,1 [7] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - section
+                HtmlContent - (39:1,8 [7] x:\dir\subdir\Test\TestComponent.cshtml)
+                    LazyIntermediateToken - (39:1,8 [7] x:\dir\subdir\Test\TestComponent.cshtml) - Html -  One { 
+                MarkupBlock -  - <p>Content</p> }
diff --git a/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/SectionDirective_NotAllowed/TestComponent.mappings.txt b/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/SectionDirective_NotAllowed/TestComponent.mappings.txt
new file mode 100644
index 00000000000..3f1bbf943f0
--- /dev/null
+++ b/src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentRuntimeCodeGenerationTest/SectionDirective_NotAllowed/TestComponent.mappings.txt
@@ -0,0 +1,10 @@
+Source Location: (2:0,2 [26] x:\dir\subdir\Test\TestComponent.cshtml)
+| var section = "Section"; |
+Generated Location: (735:21,0 [26] )
+| var section = "Section"; |
+
+Source Location: (32:1,1 [7] x:\dir\subdir\Test\TestComponent.cshtml)
+|section|
+Generated Location: (922:29,24 [7] )
+|section|
+