Hello Rust example

The following is an example of constructing a Rust binary that depends on a Rust library.

Rust modules are currently confined to specific directories defined in build/soong/rust/config/allowed_list.go. The following helloWorld module uses the external/rust directory to avoid modifying this list.

From the AOSP source root

mkdir -p external/rust/hello_rust/src/ mkdir -p external/rust/libsimple_printer/src/

Create external/rust/hello_rust/src/hello_rust.rs with the following contents:

use simple_printer; fn main() {  simple_printer::print_hello_rust(); }

Create external/rust/libsimple_printer/src/lib.rs file with the following contents:

pub fn print_hello_rust() {  println!("Hello Rust!"); }

Create an external/rust/hello_rust/Android.bp file with the following contents:

rust_binary {  name: "hello_rust",  // srcs must contain a single source file, the entry point source.  srcs: ["src/hello_rust.rs"],  // rustlibs are Rust library dependencies. The type, rlib (static) or dylib  // (dynamic), are chosen automatically based on module type and target  // to avoid linkage issues.  rustlibs: ["libsimple_printer"],  // define any additional compilation flags  flags: [  "-C debug-assertions=yes",  ],  // cc libraries can be linked in to rust binaries and libraries through the  // shared_libs and static_libs properties. These are not needed for this  // simple example, so they are not included. }

Create an external/rust/libsimple_printer/Android.bp file with the following contents:

// rust_library provides dylib and rlib variants. rust_library {  //name or stem properties must be of the form lib<crate_name><any_suffix>  name: "libsimple_printer",  //crate_name must match the name used in source (e.g. extern crate <name>)  crate_name: "simple_printer",  //srcs must contain a single source file, the entry point source  srcs: ["src/lib.rs"], }

Finally, build your hello_rust module:

source build/envsetup.sh lunch aosp_arm64-eng m hello_rust