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