Feature request: support Protocol-based ir.Data interface

[weinbe58]

Summary

Allow compiler attribute types to satisfy the ir.Data interface via structural typing (Python Protocol) instead of requiring inheritance from a concrete base class.

Motivation

In bloqade-lanes, we have Rust-backed types (via PyO3) that carry device-level data (addresses, lane descriptors, etc.) used as IR attributes. These types need to satisfy Kirin's ir.Data interface to participate in the compiler pipeline.

Since PyO3 #[pyclass] types cannot inherit from Python-defined base classes (a known PyO3 limitation), we currently maintain a separate layer of pure-Python wrapper classes whose sole purpose is to:

1. Inherit from the Kirin ir.Data / Encoder base class
2. Delegate all methods to the underlying Rust object via self._inner

This creates a three-layer type stack (Rust → PyO3 binding → Python wrapper) that adds code complexity, maintenance burden, and conversion overhead at every IR boundary.

If ir.Data were defined as a Protocol (PEP 544), any type that implements the required methods would automatically satisfy the interface — no inheritance needed. Rust-backed types could participate directly in the IR without wrappers.

Proposed change

Define the ir.Data interface as a typing.Protocol (or provide a Protocol alternative alongside the current base class for backward compatibility):

from typing import Protocol, runtime_checkable

@runtime_checkable
class Data(Protocol):
    # whatever methods/properties ir.Data requires
    ...

This would allow any type — including PyO3 extension types — to satisfy the interface through structural subtyping rather than nominal inheritance.

Backward compatibility

A Protocol-based approach could coexist with the current base class:

• Existing code that inherits from ir.Data would continue to work
• Type checks using isinstance() would work if the Protocol is @runtime_checkable
• New types (especially FFI types) could satisfy the interface without inheritance

Context

• PyO3 limitation: #991 — Rust #[pyclass] cannot inherit from Python classes
• bloqade-lanes uses Kirin for its IR framework and has ~10 address/descriptor types that need the ir.Data interface