Fix Razor parsing for adjacent comment delimiters in code blocks

[Copilot]

Razor views containing adjacent comment boundaries like *@@* could make RazorSourceGenerator fail with CS8785, preventing generated views from contributing to output. The failure did not identify the source view, making the broken file hard to diagnose.

• Parser

  • Avoid consuming the token after an embedded Razor comment during C# bracket balancing.
  • This lets adjacent comment boundaries parse as distinct Razor comments instead of leaking into generated C#.

• Regression coverage

  • Added a source-generator test for the MVC view pattern from the issue.
  • Added MVC integration test baselines that assert the Razor syntax tree, Razor IR, and generated C# for the adjacent comment delimiter case.
  • Verifies generation succeeds, Razor comment nodes are preserved in the syntax tree, and Razor comment delimiters are not emitted into generated C#.

@class = ""
@*                @class = ""
*@@*                @class = ""
*@            }))

[davidwengier]

@copilot can you please add an integration test that asserts test baselines so we can check the syntax tree and code gen are exactly what we'd expect. See tests that call AssertDocumentNodeMatchesBaseline and AssertCSharpDocumentMatchesBaseline for example.

[Copilot]

@copilot can you please add an integration test that asserts test baselines so we can check the syntax tree and code gen are exactly what we'd expect. See tests that call `AssertDocumentNodeMatchesBas...

Added the integration baseline coverage in f39ff06, asserting both the Razor IR and generated C# for the adjacent comment delimiter case.

[Copilot]

Pull request overview

This PR fixes a Razor legacy C# parsing edge case where bracket balancing could accidentally consume the token following an embedded Razor comment, breaking parsing for adjacent Razor comment delimiters inside code blocks and potentially causing source-generation/compilation failures. It also adds regression coverage at both the source-generator and MVC integration-test layers to ensure adjacent comment boundaries are preserved in the Razor syntax tree and not emitted into generated C#.

Changes:

• Update CSharpCodeParser.Balance to restart the balancing loop immediately after parsing an embedded transition/comment, preventing the next token from being consumed as C#.
• Add a shared integration-test helper to baseline-verify Razor syntax trees (.stree.txt).
• Add source-generator + MVC integration tests (with new .cshtml, .ir.txt, .stree.txt, .codegen.cs baselines) for the adjacent-comment-delimiter scenario.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/Razor/src/Shared/Microsoft.AspNetCore.Razor.Test.Common/Language/IntegrationTests/IntegrationTestBase.cs	Adds AssertSyntaxTreeMatchesBaseline to enable .stree.txt baselines for integration tests.
src/Razor/src/Compiler/test/Microsoft.NET.Sdk.Razor.SourceGenerators.UnitTests/RazorSourceGeneratorTests.cs	Adds a source-generator regression test ensuring generation succeeds and comment delimiters don’t leak into generated C#.
src/Razor/src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/Legacy/CSharpCodeParser.cs	Fixes balancing behavior by continuing the loop after parsing embedded transitions/comments.
src/Razor/src/Compiler/Microsoft.AspNetCore.Mvc.Razor.Extensions/test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/RazorComment_AdjacentCommentsInCodeBlock.stree.txt	New Razor syntax tree baseline asserting adjacent Razor comments are distinct nodes.
src/Razor/src/Compiler/Microsoft.AspNetCore.Mvc.Razor.Extensions/test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/RazorComment_AdjacentCommentsInCodeBlock.ir.txt	New Razor IR baseline for the regression scenario.
src/Razor/src/Compiler/Microsoft.AspNetCore.Mvc.Razor.Extensions/test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/RazorComment_AdjacentCommentsInCodeBlock.cshtml	New integration-test input view reproducing adjacent comment delimiters in a code block.
src/Razor/src/Compiler/Microsoft.AspNetCore.Mvc.Razor.Extensions/test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/RazorComment_AdjacentCommentsInCodeBlock.codegen.cs	New generated C# baseline verifying comment delimiters are not emitted into output.
src/Razor/src/Compiler/Microsoft.AspNetCore.Mvc.Razor.Extensions/test/IntegrationTests/CodeGenerationIntegrationTest.cs	Adds an MVC integration test that asserts syntax tree + IR + generated C# baselines for the scenario.