Build Rules

The Android build system (Soong) supports Rust via a number of modules:

Module Type	Description
`rust_binary`	Produces a Rust binary.
`rust_library`	Produces a Rust library, and provides both `rlib` and `dylib` variants.
`rust_ffi`	Produces a Rust C library usable by `cc` modules, and provides both static and shared variants.
`rust_proc_macro`	Produces a `proc-macro` Rust library. These are analogous to compiler plugins.
`rust_test`	Produces a Rust test binary that uses the standard Rust test harness.
`rust_fuzz`	Produces a Rust fuzz binary leveraging `libfuzzer`.
`rust_protobuf`	Generates source and produces a Rust library that provides an interface for a particular protobuf.
`rust_bindgen`	Generates source and produces a Rust library containing Rust bindings to C libraries.

We will look at rust_binary and rust_library next.

Additional items speaker may mention:

Cargo is not optimized for multi-language repos, and also downloads packages from the internet.
For compliance and performance, Android must have crates in-tree. It must also interop with C/C++/Java code. Soong fills that gap.
Soong has many similarities to Bazel, which is the open-source variant of Blaze (used in google3).
Fun fact: Data from Star Trek is a Soong-type Android.