Merge #466

466: Fix for type aliases in `mod app`, UB in `spawn_at`, and `#[cfg]` in hardware tasks r=AfoHT a=korken89

Type aliases such as the following did not work in `0.6-alpha`:

```rust
use rtic::app;

#[app(device = lm3s6965, dispatchers = [SSI0])]
mod app {
    type Test = u32;

    #[task]
    fn t1(_: t1::Context, _val: Test) {}
}
```

Plus that accessing associated constants of monotonic timers was not working as it should dues to the syntax and codegen transforming:

```rust
    #[monotonic(binds = SysTick, default = true)]
    type MyMono = DwtSystick<8_000_000>; // 8 MHz
```

into

```rust
    mod MyMono {
        // ...
    }
```

causing the original `type MyMono` to not exist anymore.

This PR fixes this and adds test to check for this by doing the following expansion instead:

 ```rust
    #[monotonic(binds = SysTick, default = true)]
    type MyMono = DwtSystick<8_000_000>; // 8 MHz
```

into

```rust
    type MyMono = DwtSystick<8_000_000>;

    mod monotonics {
        mod MyMono {
            // ...
        }

        // And other monotonics go here as well
    }
```

**Breaking change**

This causes a breaking change in accessing the `MyMono::now()` method which now exists under `monotonics::MyMono::now()`.

---

Moreover a UB issue was found and fixed in `spawn_at` and hardware tasks properly propagate `#[cfg]`s.

Closes #460
Closes #462
Closes #463

Co-authored-by: Emil Fresk <emil.fresk@gmail.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/macros/src/codegen/hardware_tasks.rs b/macros/src/codegen/hardware_tasks.rs
index 4a1d7492..540b95e5 100644
--- a/macros/src/codegen/hardware_tasks.rs
+++ b/macros/src/codegen/hardware_tasks.rs
@@ -37,12 +37,16 @@ pub fn codegen(
 
         let symbol = task.args.binds.clone();
         let priority = task.args.priority;
+        let cfgs = &task.cfgs;
+        let attrs = &task.attrs;
 
         let app_name = &app.name;
         let app_path = quote! {crate::#app_name};
         mod_app.push(quote!(
             #[allow(non_snake_case)]
             #[no_mangle]
+            #(#attrs)*
+            #(#cfgs)*
             unsafe fn #symbol() {
                 const PRIORITY: u8 = #priority;