dyn-loader

Dynamic library loader with dyn-fat-pointer-bridge for loading Rust trait objects from .so/.dylib plugin files.

DynLib: wraps libloading::Library with Arc for shared ownership.
AbiDynFatPtr: ABI-stable representation of a Rust fat pointer (data ptr + vtable ptr), #[repr(C)].
AbiStableDynRef: fat pointer + retain/release function pointers, enabling safe cross-boundary Arc-like reference counting.
SafeArcDyn: safe, cloneable handle over an AbiStableDynRef.
DynPlugin: loaded plugin holding a SafeArcDyn<T> that dereferences to &T for calling trait methods on the loaded object.

⚠️ IMPORTANT — ABI compatibility / compiler version alignment

You must strictly align the Rust compiler version. Every library and executable that exchanges dyn fat pointers across the boundary must be built with the exact same Rust compiler version to guarantee a stable ABI. Rust makes no ABI stability guarantees between compiler releases (vtable layout, metadata encoding, etc. may change). Mixing compiler versions between the host and plugins is undefined behavior.

Pin one toolchain (e.g. via rust-toolchain.toml) and rebuild all crates, libs and executables together with that single version.

Usage

Plugin side (the `.so`/`.dylib`)

use dyn_loader::{AbiStableDynRef, SafeArcDyn};
use std::sync::Arc;

#[no_mangle]
pub extern "C" fn core_ast_transform_entry() -> AbiStableDynRef {
    SafeArcDyn::from_arc(Arc::new(MyTransform) as Arc<dyn Transform>).into_abi()
}

Host side

use dyn_loader::DynPlugin;

let plugin = DynPlugin::<dyn Transform>::load(
    "libmy_transform.so",
    b"core_ast_transform_entry\0",
)?;
let transform: &dyn Transform = plugin.trait_ref();

Safety

Loading dynamic libraries and unpacking raw fat pointers is inherently unsafe. See the # Safety sections on each API. The retain/release function pointers give you Arc-like reference counting across the library boundary, but the caller is still responsible for ABI compatibility (see the warning above).

License

MIT

dyn-loader 0.1.0