Remove syntax annotations from the Razor compiler #12345
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davidwengier
approved these changes
Oct 16, 2025
Make RazorSyntaxGenerator runnable again.
Add an "EditHandler" property to every syntax node node that has a "ChunkGenerator" property.
This change updates the compiler to update and use SpanEditHandlers from the syntax model rather than as annotations.
- Use FrozenSet<SyntaxKind> instead of ImmutableHashSet<SyntaxKind> - Don't create sets of one item
In addition to the mechanical work of transitioning from annotations to the syntax model, I added a handful of helpers to RazorDirectiveSyntax and used them throughout tooling layer.
…ve from annotations
Here's the thing: the Razor compiler doesn't need syntax annotations. Originally, annotations were added to Roslyn to support the IDE when making tree transformations. However, Razor tooling doesn't actually perform any tree transformations. So, tooling doesn't use annotations. The problem is that the compiler *does* use annotations to stuff data onto syntax nodes -- data that should have been part of the syntax model in the first place. Now that all compiler data has been moved into the syntax model, syntax annotations are pure overhead and can be removed.
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DustinCampbell
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@chsienki: PTAL when you get a chance. |
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I recommend reviewing this PR commit-by-commit. Each commit represents a distinct change.
Syntax annotations were originally added to Roslyn's syntax model to support the IDE. When writing IDE code, it can be very useful to mark a node, perform a tree transformation, and then use the annotation to get back to that node. However, the Razor tooling layer doesn't perform tree transformations in that way. In fact, the only uses of syntax annotations are in the compiler itself where annotations are used to tuck compiler data onto nodes. This results in a lot of overhead for a handful of data properties that can just be part of the syntax model.
This change does exactly that. It takes compiler data stored as annotations --
SpanEditHandler,IsMarkupTransition,DirectiveDescriptor,TagHelperInfo, andTagHelperAttributeInfo-- and moves that data onto the syntax model. With that complete, syntax annotations are pure overhead and can be deleted completely.CI Build: https://dev.azure.com/dnceng/internal/_build/results?buildId=2818010&view=results
Test Insertion: https://dev.azure.com/devdiv/DevDiv/_git/VS/pullrequest/680258
Toolset Run: https://dev.azure.com/dnceng/internal/_build/results?buildId=2818016&view=results