rego-cpp Built-in Function Development

Add, update, and remove OPA Rego built-in functions in rego-cpp.

When to Use

• Implementing a new builtin (replacing a placeholder or adding from scratch)
• Adding a new OPA builtin namespace (new src/builtins/<namespace>.cc file)
• Updating builtin declarations to track a new OPA version
• Replacing placeholder stubs with real implementations
• Removing deprecated builtins
• Debugging builtin dispatch or registration issues

Architecture Overview

Built-in functions follow a three-layer architecture: