Rex Proc Macros (rexlang-proc-macro)

This crate provides procedural macros for bridging Rust types and Rex values.

#[derive(Rex)]

The derive generates:

• an ADT declaration suitable for injection into an Engine
• ADT-family discovery so inject_rex registers all reachable acyclic derived dependencies
• IntoPointer / FromPointer implementations to convert between Rust values and Rex runtime values

In practice this means injecting the top-level derived Rust type is enough for acyclic families of derived ADTs; manual dependency ordering is no longer required. Cyclic ADT families are still rejected at registration time.

Leaf types that implement RexType / IntoPointer / FromPointer but are not RexAdts now work without any field annotation. The derive uses RexType::collect_rex_family, whose default implementation is a no-op for non-ADT leaves.

The generated code now targets the public rexlang crate path, so embedders only need rexlang instead of rexlang-core.