add some tests

tests/cfail/used-free-interrupt-2.rs

@@ -0,0 +1,21 @@
+#![no_main]
+#![no_std]
+
+extern crate lm3s6965;
+extern crate panic_halt;
+extern crate rtfm;
+
+use rtfm::app;
+
+#[app(device = lm3s6965)]
+const APP: () = {
+    #[init]
+    fn init() {}
+
+    #[interrupt(binds = UART0)]
+    fn foo() {} //~ ERROR free interrupts (`extern { .. }`) can't be used as interrupt handlers
+
+    extern "C" {
+        fn UART0();
+    }
+};

tests/cpass/binds.rs

@@ -0,0 +1,25 @@
+//! Check that `binds` works as advertised
+#![no_main]
+#![no_std]
+
+extern crate lm3s6965;
+extern crate panic_halt;
+extern crate rtfm;
+
+use rtfm::app;
+
+#[app(device = lm3s6965)]
+const APP: () = {
+    #[init]
+    fn init() {}
+
+    #[exception(binds = SVCall)]
+    fn foo() {}
+
+    #[interrupt(binds = UART0)]
+    fn bar() {}
+};
+
+fn foo_trampoline(_: foo::Context) {}
+
+fn bar_trampoline(_: bar::Context) {}