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>

7 files changed, 75 insertions, 39 deletions

diff --git a/examples/t-schedule.rs b/examples/t-schedule.rs
index ef04c451..5e38dbaf 100644
--- a/examples/t-schedule.rs
+++ b/examples/t-schedule.rs
@@ -26,24 +26,27 @@ mod app {
         // Task without message passing
 
         // Not default
-        let _: Result<foo::MyMono::SpawnHandle, ()> = foo::MyMono::spawn_at(MyMono::now());
+        let _: Result<foo::MyMono::SpawnHandle, ()> =
+            foo::MyMono::spawn_at(monotonics::MyMono::now());
         let handle: Result<foo::MyMono::SpawnHandle, ()> = foo::MyMono::spawn_after(Seconds(1_u32));
         let _: Result<foo::MyMono::SpawnHandle, ()> =
             handle.unwrap().reschedule_after(Seconds(1_u32));
 
         let handle: Result<foo::MyMono::SpawnHandle, ()> = foo::MyMono::spawn_after(Seconds(1_u32));
-        let _: Result<foo::MyMono::SpawnHandle, ()> = handle.unwrap().reschedule_at(MyMono::now());
+        let _: Result<foo::MyMono::SpawnHandle, ()> =
+            handle.unwrap().reschedule_at(monotonics::MyMono::now());
 
         let handle: Result<foo::MyMono::SpawnHandle, ()> = foo::MyMono::spawn_after(Seconds(1_u32));
         let _: Result<(), ()> = handle.unwrap().cancel();
 
         // Using default
-        let _: Result<foo::SpawnHandle, ()> = foo::spawn_at(MyMono::now());
+        let _: Result<foo::SpawnHandle, ()> = foo::spawn_at(monotonics::MyMono::now());
         let handle: Result<foo::SpawnHandle, ()> = foo::spawn_after(Seconds(1_u32));
         let _: Result<foo::SpawnHandle, ()> = handle.unwrap().reschedule_after(Seconds(1_u32));
 
         let handle: Result<foo::SpawnHandle, ()> = foo::spawn_after(Seconds(1_u32));
-        let _: Result<foo::SpawnHandle, ()> = handle.unwrap().reschedule_at(MyMono::now());
+        let _: Result<foo::SpawnHandle, ()> =
+            handle.unwrap().reschedule_at(monotonics::MyMono::now());
 
         let handle: Result<foo::SpawnHandle, ()> = foo::spawn_after(Seconds(1_u32));
         let _: Result<(), ()> = handle.unwrap().cancel();
@@ -51,7 +54,8 @@ mod app {
         // Task with single message passing
 
         // Not default
-        let _: Result<bar::MyMono::SpawnHandle, u32> = bar::MyMono::spawn_at(MyMono::now(), 0);
+        let _: Result<bar::MyMono::SpawnHandle, u32> =
+            bar::MyMono::spawn_at(monotonics::MyMono::now(), 0);
         let handle: Result<bar::MyMono::SpawnHandle, u32> =
             bar::MyMono::spawn_after(Seconds(1_u32), 0);
         let _: Result<bar::MyMono::SpawnHandle, ()> =
@@ -59,19 +63,21 @@ mod app {
 
         let handle: Result<bar::MyMono::SpawnHandle, u32> =
             bar::MyMono::spawn_after(Seconds(1_u32), 0);
-        let _: Result<bar::MyMono::SpawnHandle, ()> = handle.unwrap().reschedule_at(MyMono::now());
+        let _: Result<bar::MyMono::SpawnHandle, ()> =
+            handle.unwrap().reschedule_at(monotonics::MyMono::now());
 
         let handle: Result<bar::MyMono::SpawnHandle, u32> =
             bar::MyMono::spawn_after(Seconds(1_u32), 0);
         let _: Result<u32, ()> = handle.unwrap().cancel();
 
         // Using default
-        let _: Result<bar::SpawnHandle, u32> = bar::spawn_at(MyMono::now(), 0);
+        let _: Result<bar::SpawnHandle, u32> = bar::spawn_at(monotonics::MyMono::now(), 0);
         let handle: Result<bar::SpawnHandle, u32> = bar::spawn_after(Seconds(1_u32), 0);
         let _: Result<bar::SpawnHandle, ()> = handle.unwrap().reschedule_after(Seconds(1_u32));
 
         let handle: Result<bar::SpawnHandle, u32> = bar::spawn_after(Seconds(1_u32), 0);
-        let _: Result<bar::SpawnHandle, ()> = handle.unwrap().reschedule_at(MyMono::now());
+        let _: Result<bar::SpawnHandle, ()> =
+            handle.unwrap().reschedule_at(monotonics::MyMono::now());
 
         let handle: Result<bar::SpawnHandle, u32> = bar::spawn_after(Seconds(1_u32), 0);
         let _: Result<u32, ()> = handle.unwrap().cancel();
@@ -80,7 +86,7 @@ mod app {
 
         // Not default
         let _: Result<baz::MyMono::SpawnHandle, (u32, u32)> =
-            baz::MyMono::spawn_at(MyMono::now(), 0, 1);
+            baz::MyMono::spawn_at(monotonics::MyMono::now(), 0, 1);
         let handle: Result<baz::MyMono::SpawnHandle, (u32, u32)> =
             baz::MyMono::spawn_after(Seconds(1_u32), 0, 1);
         let _: Result<baz::MyMono::SpawnHandle, ()> =
@@ -88,19 +94,22 @@ mod app {
 
         let handle: Result<baz::MyMono::SpawnHandle, (u32, u32)> =
             baz::MyMono::spawn_after(Seconds(1_u32), 0, 1);
-        let _: Result<baz::MyMono::SpawnHandle, ()> = handle.unwrap().reschedule_at(MyMono::now());
+        let _: Result<baz::MyMono::SpawnHandle, ()> =
+            handle.unwrap().reschedule_at(monotonics::MyMono::now());
 
         let handle: Result<baz::MyMono::SpawnHandle, (u32, u32)> =
             baz::MyMono::spawn_after(Seconds(1_u32), 0, 1);
         let _: Result<(u32, u32), ()> = handle.unwrap().cancel();
 
         // Using default
-        let _: Result<baz::SpawnHandle, (u32, u32)> = baz::spawn_at(MyMono::now(), 0, 1);
+        let _: Result<baz::SpawnHandle, (u32, u32)> =
+            baz::spawn_at(monotonics::MyMono::now(), 0, 1);
         let handle: Result<baz::SpawnHandle, (u32, u32)> = baz::spawn_after(Seconds(1_u32), 0, 1);
         let _: Result<baz::SpawnHandle, ()> = handle.unwrap().reschedule_after(Seconds(1_u32));
 
         let handle: Result<baz::SpawnHandle, (u32, u32)> = baz::spawn_after(Seconds(1_u32), 0, 1);
-        let _: Result<baz::SpawnHandle, ()> = handle.unwrap().reschedule_at(MyMono::now());
+        let _: Result<baz::SpawnHandle, ()> =
+            handle.unwrap().reschedule_at(monotonics::MyMono::now());
 
         let handle: Result<baz::SpawnHandle, (u32, u32)> = baz::spawn_after(Seconds(1_u32), 0, 1);
         let _: Result<(u32, u32), ()> = handle.unwrap().cancel();
diff --git a/examples/type-usage.rs b/examples/type-usage.rs
new file mode 100644
index 00000000..9bb7eb8d
--- /dev/null
+++ b/examples/type-usage.rs
@@ -0,0 +1,15 @@
+//! examples/type-usage.rs
+
+#![no_main]
+#![no_std]
+
+use panic_semihosting as _; // panic handler
+use rtic::app;
+
+#[app(device = lm3s6965, dispatchers = [SSI0])]
+mod app {
+    type Test = u32;
+
+    #[task]
+    fn t1(_: t1::Context, _val: Test) {}
+}
diff --git a/macros/Cargo.toml b/macros/Cargo.toml
index f14b1046..203a2bb1 100644
--- a/macros/Cargo.toml
+++ b/macros/Cargo.toml
@@ -22,5 +22,4 @@ proc-macro2 = "1"
 proc-macro-error = "1"
 quote = "1"
 syn = "1"
-rtic-syntax = "0.5.0-alpha.1"
-
+rtic-syntax = "0.5.0-alpha.2"
diff --git a/macros/src/codegen.rs b/macros/src/codegen.rs
index c5d95687..cf728a7d 100644
--- a/macros/src/codegen.rs
+++ b/macros/src/codegen.rs
@@ -112,8 +112,6 @@ pub fn app(app: &App, analysis: &Analysis, extra: &Extra) -> TokenStream2 {
             let user_imports = &app.user_imports;
 
             quote! {
-                pub use rtic::Monotonic as _;
-
                 #[doc = #doc]
                 #[allow(non_snake_case)]
                 pub mod #name {
@@ -143,6 +141,18 @@ pub fn app(app: &App, analysis: &Analysis, extra: &Extra) -> TokenStream2 {
         })
         .collect();
 
+    let monotonics = if !monotonic_parts.is_empty() {
+        quote!(
+            pub use rtic::Monotonic as _;
+
+            /// Holds static methods for each monotonic.
+            pub mod monotonics {
+                #(#monotonic_parts)*
+            }
+        )
+    } else {
+        quote!()
+    };
     let rt_err = util::rt_err_ident();
 
     quote!(
@@ -151,7 +161,7 @@ pub fn app(app: &App, analysis: &Analysis, extra: &Extra) -> TokenStream2 {
             /// Always include the device crate which contains the vector table
             use #device as #rt_err;
 
-            #(#monotonic_parts)*
+            #monotonics
 
             #(#user_imports)*
 
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;
 
diff --git a/macros/src/codegen/module.rs b/macros/src/codegen/module.rs
index e15aab1c..50146c02 100644
--- a/macros/src/codegen/module.rs
+++ b/macros/src/codegen/module.rs
@@ -21,7 +21,7 @@ pub fn codegen(
     let app_name = &app.name;
     let app_path = quote! {crate::#app_name};
 
-    let all_task_names: Vec<_> = app
+    let all_task_imports: Vec<_> = app
         .software_tasks
         .iter()
         .map(|(name, st)| {
@@ -46,6 +46,13 @@ pub fn codegen(
                 quote!()
             }
         }))
+        .chain(app.user_types.iter().map(|ty| {
+            let t = &ty.ident;
+            quote! {
+                #[allow(unused_imports)]
+                use super::#t;
+            }
+        }))
         .collect();
 
     let mut lt = None;
@@ -230,7 +237,7 @@ pub fn codegen(
         // Spawn caller
         items.push(quote!(
 
-        #(#all_task_names)*
+        #(#all_task_imports)*
 
         #(#cfgs)*
         /// Spawns the task directly
@@ -268,7 +275,7 @@ pub fn codegen(
             let tq = util::mark_internal_ident(&tq);
             let t = util::schedule_t_ident();
             let m = &monotonic.ident;
-            let mono_type = &monotonic.ty;
+            let mono_type = &monotonic.ident;
             let m_ident = util::monotonic_ident(&monotonic_name);
             let m_ident = util::mark_internal_ident(&m_ident);
             let m_isr = &monotonic.args.binds;
@@ -300,10 +307,6 @@ pub fn codegen(
             items.push(quote!(
             /// Holds methods related to this monotonic
             pub mod #m {
-                // #(
-                //     #[allow(unused_imports)]
-                //     use #app_path::#all_task_names as #all_task_names;
-                // )*
                 use super::*;
                 #[allow(unused_imports)]
                 use #app_path::#tq_marker;
@@ -341,7 +344,7 @@ pub fn codegen(
                         where D: rtic::time::duration::Duration + rtic::time::fixed_point::FixedPoint,
                                  D::T: Into<<#app_path::#mono_type as rtic::time::Clock>::T>,
                     {
-                        self.reschedule_at(#app_path::#m::now() + duration)
+                        self.reschedule_at(#app_path::monotonics::#m::now() + duration)
                     }
 
                     pub fn reschedule_at(self, instant: rtic::time::Instant<#app_path::#mono_type>) -> Result<Self, ()>
@@ -373,7 +376,7 @@ pub fn codegen(
                     let instant = if rtic::export::interrupt::free(|_| unsafe { #app_path::#m_ident.is_none() }) {
                         rtic::time::Instant::new(0)
                     } else {
-                        #app_path::#m::now()
+                        #app_path::monotonics::#m::now()
                     };
 
                     spawn_at(instant + duration #(,#untupled)*)
@@ -411,17 +414,11 @@ pub fn codegen(
 
                                 let tq = unsafe { &mut *#app_path::#tq.as_mut_ptr() };
 
-                                if let Some(mono) = #app_path::#m_ident.as_mut() {
-                                    tq.enqueue_unchecked(
-                                        nr,
-                                        || #enable_interrupt,
-                                        || #pend,
-                                        mono)
-                                } else {
-                                    // We can only use the timer queue if `init` has returned, and it
-                                    // writes the `Some(monotonic)` we are accessing here.
-                                    core::hint::unreachable_unchecked()
-                                }
+                                tq.enqueue_unchecked(
+                                    nr,
+                                    || #enable_interrupt,
+                                    || #pend,
+                                    #app_path::#m_ident.as_mut());
 
                                 Ok(SpawnHandle { marker })
                             })
diff --git a/src/tq.rs b/src/tq.rs
index 38640259..985e0f88 100644
--- a/src/tq.rs
+++ b/src/tq.rs
@@ -42,7 +42,7 @@ where
         nr: NotReady<Mono, Task>,
         enable_interrupt: F1,
         pend_handler: F2,
-        mono: &mut Mono,
+        mono: Option<&mut Mono>,
     ) where
         F1: FnOnce(),
         F2: FnOnce(),
@@ -57,7 +57,9 @@ where
 
         if if_heap_max_greater_than_nr {
             if Mono::DISABLE_INTERRUPT_ON_EMPTY_QUEUE && self.0.is_empty() {
-                mono.enable_timer();
+                if let Some(mono) = mono {
+                    mono.enable_timer();
+                }
                 enable_interrupt();
             }