Merge #613

613: Rust stable support r=Dirbaio a=Dirbaio

This PR adds (limited) stable Rust support!

The drawbacks are: 

- No `#[embassy::task]`, `#[embassy::main]`. (requires `type_alias_impl_trait`). You have to manually allocate the tasks somewhere they'll live forever. See [example](https://github.com/embassy-rs/embassy/blob/master/examples/nrf/src/bin/raw_spawn.rs)
- No async trait impls (requires GATs). Note that the full API surface of HALs is still available through inherent methods: #552 #581 
- Some stuff is not constructible in const (requires `const_fn_trait_bound`), although there's an (ugly) workaround for the generic `Mutex`.

So it's not that bad in the end, it's fully usable for shipping production-ready firmwares. We'll still recommend nightly as the default, until GATs and `type_alias_impl_trait` are stable.

Co-authored-by: Dario Nieuwenhuis <[email protected]>

3 files changed, 9 insertions, 6 deletions

diff --git a/examples/nrf/Cargo.toml b/examples/nrf/Cargo.toml
index da16bcbaf..2d9c99530 100644
--- a/examples/nrf/Cargo.toml
+++ b/examples/nrf/Cargo.toml
@@ -4,6 +4,9 @@ edition = "2018"
 name = "embassy-nrf-examples"
 version = "0.1.0"
 
+[features]
+default = ["nightly"]
+nightly = ["embassy-nrf/nightly"]
 
 [dependencies]
 embassy = { version = "0.1.0", path = "../../embassy", features = ["defmt"] }
diff --git a/examples/nrf/src/bin/mpsc.rs b/examples/nrf/src/bin/mpsc.rs
index 454fb9541..d50736d82 100644
--- a/examples/nrf/src/bin/mpsc.rs
+++ b/examples/nrf/src/bin/mpsc.rs
@@ -6,7 +6,7 @@
 mod example_common;
 
 use defmt::unwrap;
-use embassy::blocking_mutex::kind::Noop;
+use embassy::blocking_mutex::raw::NoopRawMutex;
 use embassy::channel::mpsc::{self, Channel, Sender, TryRecvError};
 use embassy::executor::Spawner;
 use embassy::time::{Duration, Timer};
@@ -19,10 +19,10 @@ enum LedState {
     Off,
 }
 
-static CHANNEL: Forever<Channel<Noop, LedState, 1>> = Forever::new();
+static CHANNEL: Forever<Channel<NoopRawMutex, LedState, 1>> = Forever::new();
 
 #[embassy::task(pool_size = 1)]
-async fn my_task(sender: Sender<'static, Noop, LedState, 1>) {
+async fn my_task(sender: Sender<'static, NoopRawMutex, LedState, 1>) {
     loop {
         let _ = sender.send(LedState::On).await;
         Timer::after(Duration::from_secs(1)).await;
diff --git a/examples/nrf/src/bin/uart_split.rs b/examples/nrf/src/bin/uart_split.rs
index 750798378..19d438c40 100644
--- a/examples/nrf/src/bin/uart_split.rs
+++ b/examples/nrf/src/bin/uart_split.rs
@@ -6,7 +6,7 @@
 mod example_common;
 use example_common::*;
 
-use embassy::blocking_mutex::kind::Noop;
+use embassy::blocking_mutex::raw::NoopRawMutex;
 use embassy::channel::mpsc::{self, Channel, Sender};
 use embassy::executor::Spawner;
 use embassy::util::Forever;
@@ -14,7 +14,7 @@ use embassy_nrf::peripherals::UARTE0;
 use embassy_nrf::uarte::UarteRx;
 use embassy_nrf::{interrupt, uarte, Peripherals};
 
-static CHANNEL: Forever<Channel<Noop, [u8; 8], 1>> = Forever::new();
+static CHANNEL: Forever<Channel<NoopRawMutex, [u8; 8], 1>> = Forever::new();
 
 #[embassy::main]
 async fn main(spawner: Spawner, p: Peripherals) {
@@ -56,7 +56,7 @@ async fn main(spawner: Spawner, p: Peripherals) {
 }
 
 #[embassy::task]
-async fn reader(mut rx: UarteRx<'static, UARTE0>, s: Sender<'static, Noop, [u8; 8], 1>) {
+async fn reader(mut rx: UarteRx<'static, UARTE0>, s: Sender<'static, NoopRawMutex, [u8; 8], 1>) {
     let mut buf = [0; 8];
     loop {
         info!("reading...");