Implement printf (very simple version)

src/lib.rs

@@ -10,27 +10,17 @@ extern crate stdlib;
 extern crate string;
 extern crate unistd;
 
-use core::fmt;
-
-struct PanicWriter;
-
-impl fmt::Write for PanicWriter {
-    fn write_str(&mut self, s: &str) -> fmt::Result {
-        platform::write(2, s.as_bytes());
-        Ok(())
-    }
-}
-
 #[lang = "eh_personality"]
 #[no_mangle]
 pub extern "C" fn rust_eh_personality() {}
 
 #[lang = "panic_fmt"]
 #[no_mangle]
-pub extern "C" fn rust_begin_unwind(fmt: fmt::Arguments, file: &str, line: u32) -> ! {
-    use fmt::Write;
+pub extern "C" fn rust_begin_unwind(fmt: ::core::fmt::Arguments, file: &str, line: u32) -> ! {
+    use core::fmt::Write;
 
-    let _ = PanicWriter.write_fmt(format_args!("{}:{}: {}\n", file, line, fmt));
+    let mut w = platform::FileWriter(2);
+    let _ = w.write_fmt(format_args!("{}:{}: {}\n", file, line, fmt));
 
     platform::exit(1);
 }
@@ -38,9 +28,10 @@ pub extern "C" fn rust_begin_unwind(fmt: fmt::Arguments, file: &str, line: u32)
 #[allow(non_snake_case)]
 #[no_mangle]
 pub extern "C" fn _Unwind_Resume() -> ! {
-    use fmt::Write;
+    use core::fmt::Write;
 
-    let _ = PanicWriter.write_str("_Unwind_Resume\n");
+    let mut w = platform::FileWriter(2);
+    let _ = w.write_str("_Unwind_Resume\n");
 
     platform::exit(1);
 }