| Supported | Rust                           | Fastcall | V8          | Notes                                                                                                                                                                                            |
| --------- | ------------------------------ | -------- | ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| X         | bool                           | X        | Bool        |                                                                                                                                                                                                  |
| X         | i8                             | X        | Int32       |                                                                                                                                                                                                  |
| X         | u8                             | X        | Uint32      |                                                                                                                                                                                                  |
| X         | i16                            | X        | Int32       |                                                                                                                                                                                                  |
| X         | u16                            | X        | Uint32      |                                                                                                                                                                                                  |
| X         | i32                            | X        | Int32       |                                                                                                                                                                                                  |
| X         | u32                            | X        | Uint32      |                                                                                                                                                                                                  |
| X         | #[smi] ResourceId              | X        | Int32       | SMI is internally represented as a signed integer, but unsigned `#[smi]` types will be bit-converted to unsigned values for the Rust call. JavaScript code will continue to see signed integers. |
| X         | #[bigint] i64                  | X        | BigInt      |                                                                                                                                                                                                  |
| X         | #[bigint] u64                  | X        | BigInt      |                                                                                                                                                                                                  |
| X         | #[bigint] isize                | X        | BigInt      |                                                                                                                                                                                                  |
| X         | #[bigint] usize                | X        | BigInt      |                                                                                                                                                                                                  |
| X         | #[number] i64                  | X        | Number      | Result must fit within `Number.MIN_SAFE_INTEGER` and `Number.MAX_SAFE_INTEGER`                                                                                                                   |
| X         | #[number] u64                  | X        | Number      | Result must fit within `Number.MIN_SAFE_INTEGER` and `Number.MAX_SAFE_INTEGER`                                                                                                                   |
| X         | #[number] isize                | X        | Number      | Result must fit within `Number.MIN_SAFE_INTEGER` and `Number.MAX_SAFE_INTEGER`                                                                                                                   |
| X         | #[number] usize                | X        | Number      | Result must fit within `Number.MIN_SAFE_INTEGER` and `Number.MAX_SAFE_INTEGER`                                                                                                                   |
| X         | f32                            | X        | Number      |                                                                                                                                                                                                  |
| X         | f64                            | X        | Number      |                                                                                                                                                                                                  |
| X         | #[string] String               |          | String      |                                                                                                                                                                                                  |
| X         | #[string] &str                 |          | String      |                                                                                                                                                                                                  |
| X         | #[string] Cow<str>             |          | String      |                                                                                                                                                                                                  |
| X         | #[string(onebyte)] Cow<[u8]>   |          | String      |                                                                                                                                                                                                  |
| X         | #[arraybuffer] V8Slice<u8>     |          | ArrayBuffer |                                                                                                                                                                                                  |
| X         | #[arraybuffer] Vec<u8>         |          | ArrayBuffer |                                                                                                                                                                                                  |
| X         | #[arraybuffer] Box<[u8]>       |          | ArrayBuffer |                                                                                                                                                                                                  |
| X         | #[arraybuffer] bytes::BytesMut |          | ArrayBuffer |                                                                                                                                                                                                  |
| X         | #[buffer] V8Slice<u8>          |          | Uint8Array  |                                                                                                                                                                                                  |
| X         | #[buffer] Vec<u8>              |          | Uint8Array  |                                                                                                                                                                                                  |
| X         | #[buffer] Box<[u8]>            |          | Uint8Array  |                                                                                                                                                                                                  |
| X         | #[buffer] bytes::BytesMut      |          | Uint8Array  |                                                                                                                                                                                                  |
| X         | #[buffer] V8Slice<u32>         |          | Uint32Array |                                                                                                                                                                                                  |
|           | #[buffer] Vec<u32>             |          | Uint32Array |                                                                                                                                                                                                  |
|           | #[buffer] Box<[u32]>           |          | Uint32Array |                                                                                                                                                                                                  |
| X         | *const std::ffi::c_void        | X        | External    |                                                                                                                                                                                                  |
| X         | *mut std::ffi::c_void          | X        | External    |                                                                                                                                                                                                  |
| X         | v8::Local<v8::Value>           |          | any         |                                                                                                                                                                                                  |
| X         | v8::Local<v8::**V8**>          |          | **V8**      |                                                                                                                                                                                                  |
| X         | #[serde] SerdeType             |          | any         |                                                                                                                                                                                                  |
| X         | #[serde] (Tuple, Tuple)        |          | any         |                                                                                                                                                                                                  |
