// M5.A — `xx closure : Block` for an arbitrary closure signature.
//
// Pre-M5.A: the stdlib hand-rolled `Into(Block) for Closure(s32, *void) -> s32`
// didn't exist — this code wouldn't compile. Only `Closure() -> void`
// and `Closure(bool) -> void` shapes were supported.
//
// Post-M5.A: the compiler synthesises `__block_invoke_i_i_p` for this
// signature on the fly. The block's invoke trampoline forwards
// `(__sx_default_context, sx_env, arg0, arg1)` to the captured closure
// and returns the s32 result.

#import "modules/std.sx";
#import "modules/std/objc_block.sx";

// Side-effect capture so we can observe both args reached the
// closure body, even though void-returning trampolines are the
// well-tested shape.
g_sum: s32 = 0;
g_tag: *void = null;

main :: () -> s32 {
    cl := (n: s32, tag: *void) => {
        g_sum = n + 1;
        g_tag = tag;
    };
    b : Block = xx cl;

    invoke_fn : (*Block, s32, *void) -> void callconv(.c) = xx b.invoke;
    sentinel: s32 = 42;
    invoke_fn(@b, 41, xx @sentinel);

    if g_sum != 42 { print("FAIL: g_sum expected 42, got {}\n", g_sum); return 1; }
    if g_tag == null { print("FAIL: g_tag null\n"); return 1; }

    print("block multi-arg ok: sum={}\n", g_sum);
    0;
}