Merge #390

390: Spawn and schedule from anywhere r=AfoHT a=korken89

This PR moves RTIC to the spawn and schedule from anywhere syntax.

Notable changes:
 * We do no longer support non-`Send` types.
 * Some extra code is generated as any task may spawn/schedule any task. However Rust/LLVM does a great job optimizing away non used instantiations (no real code-size difference observed).
 * Worst case priority inversion has increased, but it is now predictable.

Upsides:
 * With this we should be able to support async/await.
 * RTIC tasks can now be callbacks (spawned and scheduled).
 * RTIC tasks can be stored.

Needs the following PR to land first: https://github.com/rtic-rs/rtic-syntax/pull/34

The following now works:

```rust
#[rtic::app(device = lm3s6965, monotonic = rtic::cyccnt::CYCCNT)]
mod app {
    #[init]
    fn init(mut cx: init::Context) -> init::LateResources {
        // Init stuff...

        // New spawn syntax
        foo::spawn().unwrap();

        // New schedule syntax
        bar::schedule(now + 4_000_000.cycles()).unwrap();

        init::LateResources {}
    }

    #[task]
    fn foo(_: foo::Context) {}

    #[task]
    fn bar(_: bar::Context) {}

    extern "C" {
        fn SSI0();
    }
}

```

Co-authored-by: Per Lindgren <per.lindgren@ltu.se>
Co-authored-by: Emil Fresk <emil.fresk@gmail.com>

1 files changed, 1 insertions, 15 deletions

diff --git a/macros/src/codegen/util.rs b/macros/src/codegen/util.rs
index 41ee3ca7..f04ccb23 100644
--- a/macros/src/codegen/util.rs
+++ b/macros/src/codegen/util.rs
@@ -207,23 +207,9 @@ pub fn rq_ident(priority: u8) -> Ident {
     Ident::new(&format!("P{}_RQ", priority), Span::call_site())
 }
 
-/// Generates an identifier for a "schedule" function
-///
-/// The methods of the `Schedule` structs invoke these functions.
-pub fn schedule_ident(name: &Ident) -> Ident {
-    Ident::new(&format!("schedule_{}", name.to_string()), Span::call_site())
-}
-
 /// Generates an identifier for the `enum` of `schedule`-able tasks
 pub fn schedule_t_ident() -> Ident {
-    Ident::new(&format!("T"), Span::call_site())
-}
-
-/// Generates an identifier for a "spawn" function
-///
-/// The methods of the `Spawn` structs invoke these functions.
-pub fn spawn_ident(name: &Ident) -> Ident {
-    Ident::new(&format!("spawn_{}", name.to_string()), Span::call_site())
+    Ident::new(&format!("SCHED_T"), Span::call_site())
 }
 
 /// Generates an identifier for the `enum` of `spawn`-able tasks