Print a proper message on panics

src/lib.rs

@@ -31,4 +31,11 @@ pub extern fn rust_main(multiboot_information_address: usize) {
 }
 
 #[lang = "eh_personality"] extern fn eh_personality() {}
-#[lang = "panic_fmt"] #[no_mangle] pub extern fn panic_fmt() -> ! {loop{}}
+
+#[lang = "panic_fmt"]
+#[no_mangle]
+pub extern fn panic_fmt(fmt: core::fmt::Arguments, file: &'static str, line: u32) -> ! {
+    println!("\n\nPANIC in {} at line {}:", file, line);
+    println!("    {}", fmt);
+    loop{}
+}