Add a few stubs required from std into the library

src/lib.rs

@@ -3,6 +3,9 @@
 #![feature(asm)]
 #![feature(no_core)]
 #![feature(const_fn)]
+#![feature(associated_consts)]
+#![feature(lang_items)]
+#![feature(unwind_attributes)]
 
 #![no_core]
 
@@ -23,6 +26,8 @@ pub mod spi;
 mod register;
 mod pin;
 mod usart;
+#[doc(hidden)]
+pub mod std_stub;
 
 pub enum DataDirection {
     Input,

src/std_stub.rs

@@ -0,0 +1,16 @@
+//! Stub methods that `libstd` normally defines.
+
+// These do not need to be in a module, but we group them here for clarity.
+pub mod std {
+    #[lang = "eh_personality"]
+    #[no_mangle]
+    pub unsafe extern "C" fn rust_eh_personality(_state: (), _exception_object: *mut (), _context: *mut ()) -> () {
+    }
+
+    #[lang = "panic_fmt"]
+    #[unwind]
+    pub extern fn rust_begin_panic(_msg: (), _file: &'static str, _line: u32) -> ! {
+        loop { }
+    }
+}
+