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, 0 insertions, 68 deletions

diff --git a/examples/not-send.rs b/examples/not-send.rs
deleted file mode 100644
index 18071fc5..00000000
--- a/examples/not-send.rs
+++ /dev/null
@@ -1,68 +0,0 @@
-//! `examples/not-send.rs`
-
-#![deny(unsafe_code)]
-#![deny(warnings)]
-#![no_main]
-#![no_std]
-
-use core::marker::PhantomData;
-
-use cortex_m_semihosting::debug;
-use panic_halt as _;
-use rtic::app;
-
-pub struct NotSend {
-    _0: PhantomData<*const ()>,
-}
-
-#[app(device = lm3s6965)]
-mod app {
-    use super::NotSend;
-
-    #[resources]
-    struct Resources {
-        #[init(None)]
-        shared: Option<NotSend>,
-    }
-
-    #[init(spawn = [baz, quux])]
-    fn init(c: init::Context) -> init::LateResources {
-        c.spawn.baz().unwrap();
-        c.spawn.quux().unwrap();
-
-        init::LateResources {}
-    }
-
-    #[task(spawn = [bar])]
-    fn foo(c: foo::Context) {
-        // scenario 1: message passed to task that runs at the same priority
-        c.spawn.bar(NotSend { _0: PhantomData }).ok();
-    }
-
-    #[task]
-    fn bar(_: bar::Context, _x: NotSend) {
-        // scenario 1
-    }
-
-    #[task(priority = 2, resources = [shared])]
-    fn baz(c: baz::Context) {
-        // scenario 2: resource shared between tasks that run at the same priority
-        *c.resources.shared = Some(NotSend { _0: PhantomData });
-    }
-
-    #[task(priority = 2, resources = [shared])]
-    fn quux(c: quux::Context) {
-        // scenario 2
-        let _not_send = c.resources.shared.take().unwrap();
-
-        debug::exit(debug::EXIT_SUCCESS);
-    }
-
-    // RTIC requires that unused interrupts are declared in an extern block when
-    // using software tasks; these free interrupts will be used to dispatch the
-    // software tasks.
-    extern "C" {
-        fn SSI0();
-        fn QEI0();
-    }
-}