Compliance Overview

This section describes the Roslyn compliance effort for the C# parser, using our Rust-based bsharp_parser and the bsharp_syntax AST. The goal is to automatically extract structural assertions from Roslyn tests and validate that our AST shape and key payloads match Roslyn’s expectations (normalized to our naming conventions: PascalCase, no "Syntax" suffix).

High-Level Flow

• Source: Roslyn test files in roslyn_testing/roslyn_repo/src/Compilers/CSharp/Test/Syntax/Parsing/.
• Extraction: A generator scans for UsingTree(...) blocks and parses the following DSL of N(SyntaxKind.X) nodes.
• Translation: The extracted Roslyn tree is translated and normalized to our canonical kinds and structure.
• Running: Tests are emitted into bsharp_compliance_testing, parsing provided C# snippets with bsharp_parser and comparing the actual AST with the expected structure.

Core Components

• bsharp_compliance (generator)

  • Reads Roslyn files and extracts structural expected trees.
  • Parses the Roslyn DSL (N(SyntaxKind.X), M(...), EOF()).
  • Normalizes kinds via kind_map.rs (e.g., RecordStructDeclaration → RecordDeclaration).
  • Emits Rust tests into bsharp_compliance_testing/src/generated/.

• bsharp_compliance_testing (tests & asserts)

  • Contains custom structural assertions in custom_asserts/structure_assert.rs.
  • Walks real bsharp_syntax nodes to build a comparable ExpectedTree.
  • Compares node kind shapes and selected token payloads (e.g., identifier text).

Normalization Principles

• Node names are PascalCase and omit Roslyn’s ...Syntax suffix.
• Tokens/keywords are filtered from structure; identifier text is lifted where relevant.
• Harness differences (Roslyn’s class-with-method wrappers vs. our top-level statements) are normalized at assert time when needed.

What This Validates

• Structural presence and order of major nodes (CompilationUnit, declarations, using directives, type parameters, constraint clauses, etc.).
• Selected payloads (e.g., IdentifierName.token_value).
• Deeper constructs incrementally (e.g., TypeParameterConstraintClause, “allows ref struct” constraints, record primary parameter lists).

Roadmap

• Expand kind mapping and walker coverage across more Roslyn suites.
• Tighten token payload checks where meaningful.
• Add targeted hand-authored structure tests for corner cases.