//! Generates the ONNX prost types from the vendored `proto/onnx.proto3`.
//!
//! We compile the schema with [`protox`] (a pure-Rust protobuf compiler) so the
//! build does not depend on a system `protoc` binary, then hand the resulting
//! `FileDescriptorSet` to `prost-build` for Rust code generation. The generated
//! file lands in `$OUT_DIR/onnx.rs` (named after the proto `package onnx;`) and
//! is `include!`d by `src/proto.rs`.
use PathBuf;