#![no_core]
#![no_main]
#![feature(no_core, lang_items, auto_traits)]
#![allow(internal_features)]

// These three marker traits are the minimum language items needed when core is
// not linked. They are compiler contracts, not a replacement for core.
#[lang = "pointee_sized"]
trait PointeeSized {}

#[lang = "meta_sized"]
trait MetaSized: PointeeSized {}

#[lang = "sized"]
trait Sized: MetaSized {}

#[lang = "copy"]
trait Copy {}

#[lang = "freeze"]
unsafe auto trait Freeze {}

#[lang = "eh_personality"]
extern "C" fn eh_personality() {}

#[lang = "panic_info"]
struct PanicInfo;

#[lang = "panic_impl"]
fn panic_impl(_: &PanicInfo) -> ! {
    loop {}
}

#[lang = "panic_cannot_unwind"]
fn panic_cannot_unwind() -> ! {
    loop {}
}

#[cfg(unix)]
unsafe extern "C" {
    fn write(fd: i32, buffer: *const u8, count: usize) -> isize;
}

#[cfg(windows)]
unsafe extern "system" {
    fn GetStdHandle(which: u32) -> *mut u8;
    fn WriteFile(
        handle: *mut u8,
        buffer: *const u8,
        count: u32,
        written: *mut u32,
        overlapped: *mut u8,
    ) -> i32;
    fn ExitProcess(status: u32) -> !;
}

// A string slice is a (pointer, length) pair. This keeps the public helper
// ergonomic without importing core just to call str::as_ptr and str::len.
#[repr(C)]
union StringParts<'a> {
    string: &'a str,
    bytes: (*const u8, usize),
}

fn write_stdout(message: &str) {
    let (buffer, length) = unsafe { StringParts { string: message }.bytes };

    unsafe {
        #[cfg(unix)]
        {
            write(1, buffer, length);
        }

        #[cfg(windows)]
        {
            let handle = GetStdHandle(0xffff_fff5); // STD_OUTPUT_HANDLE
            let mut written: u32 = 0;
            WriteFile(handle, buffer, length as u32, &mut written, 0 as *mut u8);
        }
    }
}

#[cfg(unix)]
#[no_mangle]
pub extern "C" fn main() -> i32 {
    write_stdout("Hello\n");
    0
}

#[cfg(windows)]
#[no_mangle]
pub extern "system" fn mainCRTStartup() -> ! {
    write_stdout("Hello\n");
    unsafe { ExitProcess(0) }
}