Add support for C# Attributes

[dymurray]

Summary

C# attributes (e.g., [Authorize], [ValidateAntiForgeryToken], [HttpPost]) are not currently captured in the stack graph, making it impossible to query for their usage with patterns like .ValidateAntiForgeryToken..

Problem

When analyzing C# code for attribute usage, queries return empty results because the TSG rules in stack-graphs.tsg do not handle attribute or attribute_list node types from tree-sitter-c-sharp.

Example: Searching for [ValidateAntiForgeryToken] attribute usage in the nerd-dinner test project:

grpcurl -plaintext -d '{
"cap": "referenced",
"condition_info": "{"referenced": {"pattern": ".ValidateAntiForgeryToken."}}"
}' localhost:9000 provider.ProviderService/Evaluate

Expected: Find all usages of the ValidateAntiForgeryToken attribute (7 occurrences in AccountController.cs)

Actual: Empty response {}

Technical Details

Tree-sitter-c-sharp correctly parses attributes. For example:

[ValidateAntiForgeryToken]
public ActionResult LogOff() { }

Produces AST structure:
method_declaration
attribute_list
attribute
identifier "ValidateAntiForgeryToken"
...

However, stack-graphs.tsg has no rules to create stack graph nodes from attribute or attribute_list nodes.

Proposed Solution

Add TSG rules to handle attributes. A starting point:

;; Attribute handling
(attribute
(identifier) @attr_name
) @attr {
node @attr.ref
attr (@attr.ref) node_reference = @attr_name
; Additional edges for FQDN resolution...
}

Considerations:

1. Attributes can have arguments: [Route("api/users")]
2. Attributes can be fully qualified: [System.ComponentModel.Description("...")]
3. Multiple attributes can be in one list: [Authorize, HttpPost]
4. Attributes apply to various targets (classes, methods, parameters, properties)

Use Cases

This feature would enable migration/modernization queries such as:

• Find all usages of deprecated attributes (e.g., [Obsolete])
• Find security-related attributes ([Authorize], [AllowAnonymous])
• Find MVC/Web API routing attributes ([HttpGet], [Route])
• Find data annotation attributes ([Required], [StringLength])

Investigation Notes

During debugging, we confirmed:

• Tree-sitter-c-sharp parses attributes correctly with identifier children
• TSG rules compile without errors but don't produce nodes
• The issue may require investigating how tree-sitter-stack-graphs matches patterns against tree-sitter-c-sharp's AST structure

##Related Files

• src/c_sharp_graph/stack-graphs.tsg - TSG rule definitions
• src/c_sharp_graph/loader.rs - Stack graph building logic
• Test file with attributes: testdata/nerd-dinner/mvc4/NerdDinner/Controllers/AccountController.cs

[shawn-hurley]

To add support for attributes someone will have to:

1. Create a query class (and add it to the namespace search) to handle the searching of attributes. (you may want to add it to the class search as well).
2. Update the TSG to handle attributes defined on methods, class, namespaces. I think for now we leave global ones out of scope.
3. Update the reference search to handle attributes

In reality this should be implemented AFTER we implement generic class search

[github-actions]

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