add cfail tests for the tasks! macro

tests/cfail/tasks-wrong-task.rs

@@ -0,0 +1,54 @@
+// error-pattern: mismatched types
+
+#![feature(used)]
+
+extern crate core;
+extern crate cortex_m;
+#[macro_use]
+extern crate cortex_m_srp;
+
+use cortex_m_srp::{C16, P0, P1};
+use device::interrupt::Exti1;
+
+tasks!(device, {
+    j1: (Exti0, P1),
+});
+
+fn init(_: C16) {}
+
+fn idle(_: P0) {}
+
+// Wrong task token. Declared Exti0, got Exti1
+fn j1(_task: Exti1, _prio: P1) {}
+
+mod device {
+    pub mod interrupt {
+        use cortex_m::interrupt::Nr;
+
+        extern "C" fn default_handler<T>(_: T) {}
+
+        pub struct Handlers {
+            pub Exti0: extern "C" fn(Exti0),
+            pub Exti1: extern "C" fn(Exti1),
+        }
+
+        pub struct Exti0;
+        pub struct Exti1;
+
+        pub enum Interrupt {
+            Exti0,
+            Exti1,
+        }
+
+        unsafe impl Nr for Interrupt {
+            fn nr(&self) -> u8 {
+                0
+            }
+        }
+
+        pub const DEFAULT_HANDLERS: Handlers = Handlers {
+            Exti0: default_handler,
+            Exti1: default_handler,
+        };
+    }
+}