Update nbody example for Rust (AssemblyScript#528)

Author: MaxGraey

examples/n-body/README.md

@@ -32,16 +32,18 @@ Benchmark
 ***Environment:***
 - MacBook Pro (Retina, 15-inch, Late 2013)
 - macOS 10.14.3
-- node.js v11.9.0
-- rustc 1.33.0-nightly (ceb251214 2019-01-16)
+- node.js v11.10.1
+- rustc 1.35.0-nightly (a9da8fc9c 2019-03-04)
 
 ***Results:***
 
 |        Target           |  Time, ***ms*** | Size, ***KB*** |
 |-------------------------|-----------------|----------------|
-| **AssemblyScript WASM** | **2901**        | **2**          |
-| AssemblyScript ASMJS    | 3720            | 19*            |
-| JavaScript              | 2716            | 5*             |
-| Rust WASM               | 2883            | 13             |
+| **AssemblyScript WASM** | **2921**        | **2**          |
+| AssemblyScript ASMJS    | 3807            | 19*            |
+| JavaScript              | 2757            | 5*             |
+| Rust WASM               | 2866            | 20 / 2**       |
 
 ___* unminified___
+
+___** after wasm-gc___

examples/n-body/build/rust.optimized.wasm

@@ -1,7 +1,7 @@
 ### Build
 
 ```bash
-cargo build --release --target=wasm32-unknown-unknown
+cargo +nightly build --release --target wasm32-unknown-unknown
 ```
 
-***Next step optimize target wasm via wasm-opt.***
+***Next step optimize target wasm via wasm-gc***

examples/n-body/rust/Cargo.lock

@@ -8,8 +8,8 @@ const compiled = new WebAssembly.Module(
 const imports = {
   env: {
     memory: new WebAssembly.Memory({ initial: 17 }),
-    abort: (filename, line, column) => {
-      throw Error("abort called at " + line + ":" + colum);
+    abort: (_filename, line, column) => {
+      throw Error("abort called at " + line + ":" + column);
     }
   }
 };

examples/n-body/rust/README.md

@@ -1,6 +1,6 @@
 // Code adopted from https://benchmarksgame-team.pages.debian.net/benchmarksgame/program/nbody-rust-1.html
 
-#![feature(core_intrinsics, panic_implementation)]
+#![feature(core_intrinsics)]
 #![no_std]
 
 use core::intrinsics;
@@ -156,18 +156,18 @@ fn offset_momentum(bodies: &mut [Planet; N_BODIES]) {
 }
 
 #[no_mangle]
-pub unsafe extern "C" fn init() {
+pub unsafe extern fn init() {
   offset_momentum(&mut BODIES);
 }
 
 #[no_mangle]
-pub unsafe extern "C" fn step() -> f64 {
+pub unsafe extern fn step() -> f64 {
   advance(&mut BODIES, 0.01);
   energy(&BODIES)
 }
 
 #[no_mangle]
-pub unsafe extern "C" fn bench(steps: i32) {
+pub unsafe extern fn bench(steps: i32) {
   for _ in 0..steps {
     advance(&mut BODIES, 0.01);
   }