AST Verifier Agent Guide

Use this file for work under ast_verifier/ together with the repository-level AGENTS.md.

Core Metadata

Attribute	Value
Name	AST Verifier
Purpose	Encodes AST invariants and validates that parser/lowering output remains structurally correct.
Primary Language	C++

Responsibilities

• Define and enforce AST integrity checks.
• Catch invalid AST states before code generation.
• Guard lowering output with explicit verifier rules.

Hard Rules

• Never disable existing AST verifier checks in a patch.
• If new AST node kinds are introduced, add verifier checks for them.
• If a lowering creates new structural patterns, add verifier checks for those patterns.
• If a parser/lowering bug produced invalid AST that passed verification, extend AST verifier accordingly.
• Treat temporarily disabled checks as still normative for new code; do not add patches that rely on bypassing invariants.

Running

• In debug builds, AST verifier runs after lowering and before code generation.
• Useful options:
  • --ast-verifier:phases=each
  • --ast-verifier:full-program
  • --ast-verifier:errors=...
  • --ast-verifier:warnings=...

References

• Component README: ast_verifier/README.md
• Repository policy: AGENTS.md