Add basic rust integration test. NFC (#22964)

Author: sbc100

.circleci/config.yml

@@ -70,6 +70,15 @@ commands:
       - run:
           name: pip install
           command: << parameters.python >> -m pip install -r requirements-dev.txt
+  install-rust:
+    steps:
+      - run:
+          name: install rust
+          command: |
+            curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y
+            export PATH=${HOME}/.cargo/bin:${PATH}
+            rustup target add wasm32-unknown-emscripten
+            echo "export PATH=\"\$HOME/.cargo/bin:\$PATH\"" >> $BASH_ENV
   install-node-version:
     description: "install a specific version of node"
     parameters:
@@ -788,8 +797,10 @@ jobs:
     executor: bionic
     environment:
       EMTEST_SKIP_NODE_CANARY: "1"
+      EMTEST_SKIP_RUST: "1"
       EMTEST_SKIP_WASM64: "1"
     steps:
+      - install-rust
       - run: apt-get install -q -y ninja-build scons ccache
       - run-tests-linux:
           # some native-dependent tests fail because of the lack of native
@@ -905,6 +916,7 @@ jobs:
       EMTEST_SKIP_WASM64: "1"
       EMTEST_SKIP_SIMD: "1"
       EMTEST_SKIP_SCONS: "1"
+      EMTEST_SKIP_RUST: "1"
       EMTEST_SKIP_NODE_CANARY: "1"
       EMTEST_BROWSER: "0"
     steps:
@@ -940,6 +952,7 @@ jobs:
       EMTEST_SKIP_EH: "1"
       EMTEST_SKIP_WASM64: "1"
       EMTEST_SKIP_SCONS: "1"
+      EMTEST_SKIP_RUST: "1"
       # Some native clang tests assume x86 clang (e.g. -sse2)
       EMTEST_LACKS_NATIVE_CLANG: "1"
       EMCC_SKIP_SANITY_CHECK: "1"

test/rust/basics/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "basics"
+edition = "2021"
+
+[lib]
+crate-type = ["staticlib"]

test/rust/basics/src/lib.rs

@@ -0,0 +1,4 @@
+#[no_mangle]
+pub extern "C" fn say_hello() {
+  println!("Hello from rust!");
+}

test/test_other.py

@@ -172,6 +172,11 @@ def requires_scons(func):
   return requires_tool('scons')(func)
 
 
+def requires_rust(func):
+  assert callable(func)
+  return requires_tool('cargo')(func)
+
+
 def requires_pkg_config(func):
   assert callable(func)
 
@@ -15360,3 +15365,18 @@ def test_fp16(self, opts):
 
   def test_embool(self):
     self.do_other_test('test_embool.c')
+
+  @requires_rust
+  def test_rust_integration_basics(self):
+    shutil.copytree(test_file('rust/basics'), 'basics')
+    self.run_process(['cargo', 'build', '--target=wasm32-unknown-emscripten'], cwd='basics')
+    lib = 'basics/target/wasm32-unknown-emscripten/debug/libbasics.a'
+    self.assertExists(lib)
+
+    create_file('main.cpp', '''
+    extern "C" void say_hello();
+    int main() {
+       say_hello();
+       return 0;
+    }''')
+    self.do_runf('main.cpp', 'Hello from rust!', emcc_args=[lib])