用自身语言 编译自身

type Point = struct { x: i32, y: i32 }

fn dist_sq(a: Point, b: Point) -> i32 {
    let dx = a.x - b.x;
    let dy = b.y - a.y;
    dx * dx + dy * dy          // 无分号，末行即返回值
}

fn classify(n: i32) -> *u8 {
    match n {                       // 带穷尽性检查
        0       => "zero",
        1..10   => "single digit",
        10 | 20 => "round number",
        _        => "other",
    }
}

extern fn printf(fmt: *u8, val: i32) -> i32;   // FFI 到 C

fn main_jhyy() -> i32 {
    let p = Point { x: 3, y: 4 };
    printf("d² = %d\n", dist_sq(p, Point { x: 0, y: 0 }));
    let s = "机会翼游";              // UTF-8 原生字面量
    0
}

$ cat compiler/tests/examples/hello.jhyy
fn main_jhyy() -> i32 {
    42
}

$ jhyy build hello.jhyy          # 第 2 代自举编译器
dbgfile "hello.jhyy"
export function w $main_jhyy() {
@start0
    dbgloc 1
    dbgloc 2
    %t1 =w copy 42
    ret %t1
}
$ ./hello.exe ; echo $?
42

$ python regress.py --all
W-097  multi-field access emit     ..... 22 skipped
  1   exit code semantics            ...... ok
  2   struct pass-by-value           ...... ok
  3   float cast / fmod / signed zero  ...... ok
  4   arena alloc + reset            ...... ok
  5   match exhaustiveness           ...... ok
  ...
158 passed, 22 skipped, 0 failed

$ jhyy_selfhost_check
all_byte_equal = true