test that function with wrong return types are rejected

Author: japaric

cortex-m-rt/tests/compile-fail/default-handler-bad-signature-2.rs

@@ -0,0 +1,18 @@
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::{entry, exception};
+
+#[entry]
+fn foo() -> ! {
+    loop {}
+}
+
+#[exception] //~ ERROR custom attribute panicked
+//~^ HELP `DefaultHandler` exception must have signature `[unsafe] fn(i16) [-> !]`
+fn DefaultHandler(_irqn: i16) -> u32 {
+    0
+}

cortex-m-rt/tests/compile-fail/exception-bad-signature-2.rs

@@ -0,0 +1,18 @@
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt;
+extern crate panic_semihosting;
+
+use cortex_m_rt::{entry, exception};
+
+#[entry]
+fn foo() -> ! {
+    loop {}
+}
+
+#[exception] //~ ERROR custom attribute panicked
+//~^ HELP `#[exception]` functions other than `DefaultHandler` and `HardFault` must have signature `[unsafe] fn() [-> !]`
+fn SysTick() -> u32 {
+    0
+}