# Rust ↔ V8 — the official binding (`rusty_v8`) Source: · crate (checked 2026-05-22) The canonical, officially-maintained Rust binding to V8 is the **`v8` crate** (repo name `rusty_v8`), maintained by the **Deno** team. It is what Deno and most Rust JS-engine work build on — there is no competing "official" binding. - Crate: `v8` — **latest `149.0.0`** (149.1.0 was yanked). - It mirrors the V8 C++ API (`Isolate`, `Context`, `HandleScope`, `Local`, `Global`, `FunctionTemplate`, …) in safe-ish Rust. ## Two ways to get the V8 library ### A. Prebuilt (default, recommended for aphrody) By default the crate's build script **downloads a prebuilt static lib** from the GitHub release matching the crate version — **Windows MSVC (`x86_64-pc-windows- msvc`) is a supported target**. So the fastest path is simply: ```toml # Cargo.toml [dependencies] v8 = "149" ``` ```bash cargo build # downloads librusty_v8 prebuilt, links it, done ``` No depot_tools, no gn, no ninja required for this path. ### B. From source To compile V8 from rusty_v8's own pinned checkout (e.g. to patch V8, or on an unsupported target): ```bash V8_FROM_SOURCE=1 cargo build -vv ``` This needs depot_tools-style prerequisites and a Python 3. ## Relevant env vars | Var | Purpose | |-----|---------| | `V8_FROM_SOURCE=1` | build V8 from source instead of downloading a prebuilt lib | | `RUSTY_V8_MIRROR` | alternate download base (URL or file path) for the prebuilt lib | | `RUSTY_V8_ARCHIVE` | use a **specific** prebuilt archive (URL or **local path**) instead of downloading | | `GN_ARGS` | extra `gn` args for the from-source build | | `CLANG_BASE_PATH` | existing LLVM/clang dir (skip the auto clang download) | | `PYTHON` | Python 3 binary (required for source builds) | ## How our `C:\src\v8` build fits in The hand-built `v8_monolith` (see [`v8-build.md`](./v8-build.md) / [`aphrody-v8-state.md`](./aphrody-v8-state.md)) is **not strictly required** if we take path A. Its value: - **Offline / pinned**: package the resulting lib and point `RUSTY_V8_ARCHIVE=C:\path\to\librusty_v8.a` (or a static `.lib`) so CI never hits GitHub releases. - **Custom V8 args / patches**: drive a from-source build and pass our `args.gn` choices via `GN_ARGS`. > Decision for aphrody: **default to the prebuilt `v8` crate** for the > Rust↔V8 surface (zero build cost, MSVC target supported). Keep the > `C:\src\v8` from-source build as the patch/offline fallback feeding > `RUSTY_V8_ARCHIVE`. This mirrors the `aphrody_web_render.dll` FFI pattern: a thin > Rust wrapper over a native engine.