Buck2 (Rust/V8)#

This repository includes a Buck2 setup for Rust builds of:

apps/runtime (flora lib + bin)
crates/flora_config
crates/flora_macros
crates/flora_typegen

Prerequisites#

buck2
Rust toolchain (cargo, rustc)
For V8 source-mode builds: gn, ninja, python3, clang/libclang (for bindgen)

Dependency Snapshot Sync#

Update Cargo metadata snapshot used by Buck2 tooling:

buck2 run //tools/buck:sync_rust_deps
# or directly:
tools/buck/sync_rust_deps.sh

Buckify third-party crates with Reindeer (for Buck-native Rust dependency graph migration):

./x buckify-rust-deps
# or directly:
tools/buck/buckify_rust_deps.sh

Reindeer config: third-party/reindeer.toml.

Important:

third-party/rust/vendor and third-party/rust/.cargo are generated-local and not committed.
tools/buck/sync_rust_deps.sh updates snapshots only (cargo-metadata.json, Cargo.lock.snapshot) and does not rewrite generated third-party/rust/BUCK2.

Helper Script#

From repo root:

# build runtime dev
./x build-dev

# build runtime release path
./x build-release

# runtime dev run
./x run-dev

# runtime release run
./x run-release

# snapshot Cargo metadata for Buck tooling
./x sync-rust-deps

# reindeer vendor + buckify
./x buckify-rust-deps

./x normalizes BINDGEN_EXTRA_CLANG_ARGS when needed (nix clang wrapper case).

Add/Update Rust Dependencies#

Use this flow whenever you add or update crates:

# 1) update manifests, then refresh lockfile
cargo check

# 2) refresh Buck snapshots
./x sync-rust-deps

# 3) regenerate reindeer Buck third-party rules
./x buckify-rust-deps

# 4) sanity-check Buck build
buck2 build //apps/runtime:flora_lib

If reindeer is missing:

nix profile install nixpkgs#reindeer

Build Targets#

# runtime (default V8 mode)
buck2 build //apps/runtime:flora_bin

# runtime release binary
buck2 build //apps/runtime:flora_bin_release

# runtime library
buck2 build //apps/runtime:flora_lib

# runtime with source V8 build path
buck2 build //apps/runtime:flora_bin_v8_source

# support crates
buck2 build //crates/flora_config:flora_config
buck2 build //crates/flora_macros:flora_macros
buck2 build //crates/flora_typegen:flora_typegen

# aggregate
buck2 build //:build_all_rust

Check/Test Targets#

buck2 build //:check_rust
buck2 build //:test_rust

V8 Source Mode#

Use //apps/runtime:flora_bin_v8_source when changing submodules/rusty_v8.

Common env before building:

export V8_FROM_SOURCE=1
export LIBCLANG_PATH=/usr/lib/llvm-19/lib
export GN=/usr/bin/gn
export NINJA=/usr/bin/ninja
export PYTHON=python3

The flora_bin_v8_source target already forces V8_FROM_SOURCE=1 for that build action.

Notes#

Buck2 here is local/dev focused; CI integration is intentionally out of scope.
Cargo remains source-of-truth for dependency resolution and lockfile state.

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