meson: Attempt to build a basic zbus Rust program with meson

```
$ meson setup build --wipe --reconfigure \
  -Dconcurrent-queue-2-rs:feature-default=true \
  -Dfutures-io-0.3-rs:feature-default=true \
  -Dfutures-lite-2-rs:feature-default=true
```

Error:

```
Executing subproject zbus-5.1.1-rs:async-io-2-rs:rustix-0.38-rs method cargo

rustix-0.38-rs| Generated Meson AST: /root/openbmc/dbus-sensors/build/subprojects/rustix-0.38.37/meson.build
rustix-0.38-rs| Project name: rustix
rustix-0.38-rs| Project version: 0.38.37
rustix-0.38-rs| Rust compiler for the host machine: rustc -C linker=cc (rustc 1.83.0)
rustix-0.38-rs| Rust linker for the host machine: rustc -C linker=cc ld.bfd 2.43.1-2

subprojects/rustix-0.38.37/meson.build:105:-1: ERROR: Unknown variable "linux_raw_sys_options".
```

Change-Id: I3283f7b5d23546fef48fcbeb6dc1736606fb7939
Signed-off-by: Peter Delevoryas <[email protected]>

meson.build

@@ -1,7 +1,13 @@
 project(
     'dbus-sensors',
     'cpp',
-    default_options: ['warning_level=3', 'werror=true', 'cpp_std=c++23'],
+    'rust',
+    default_options: [
+        'warning_level=3',
+        'werror=true',
+        'cpp_std=c++23',
+        'rust_std=2021',
+    ],
     license: 'Apache-2.0',
     version: '0.1',
     meson_version: '>=1.1.1',

src/meson.build

@@ -116,3 +116,15 @@ endif
 if get_option('tests').allowed()
     subdir('tests')
 endif
+
+subproject('zbus-5.1.1-rs', required: true)
+zbus_dep = dependency('zbus-5.1.1-rs')
+
+executable(
+    'smbpbisensor',
+    'smbpbi.rs',
+    install: true,
+    dependencies: [
+        zbus_dep,
+    ],
+)

src/smbpbi.rs

@@ -0,0 +1,33 @@
+use std::{error::Error, future::pending};
+use zbus::{connection, interface};
+
+struct Greeter {
+  count: u64
+}
+
+#[interface(name = "org.zbus.MyGreeter1")]
+impl Greeter {
+  // Can be `async` as well.
+  fn say_hello(&mut self, name: &str) -> String {
+      self.count += 1;
+      format!("Hello {}! I have been called {} times.", name, self.count)
+  }
+}
+
+// Although we use `tokio` here, you can use any async runtime of choice.
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn Error>> {
+  let greeter = Greeter { count: 0 };
+  let _conn = connection::Builder::session()?
+      .name("org.zbus.MyGreeter")?
+      .serve_at("/org/zbus/MyGreeter", greeter)?
+      .build()
+      .await?;
+
+  // Do other things or go to wait forever
+  pending::<()>().await;
+
+  Ok(())
+}
+
+

subprojects/zbus-5.1.1-rs.wrap

@@ -0,0 +1,9 @@
+[wrap-file]
+method = cargo
+directory = zbus-5.1.1
+source_url = https://crates.io/api/v1/crates/zbus/5.1.1/download
+source_filename = zbus-5.1.1.tar.gz
+source_hash = 1162094dc63b1629fcc44150bcceeaa80798cd28bcbe7fa987b65a034c258608
+
+[provide]
+dependency_names = zbus-5.1.1-rs