// FFI plan step 5.2 — generic `Into(Block) for Closure(..$args) ->
// $R` impl. One impl in stdlib covers every closure shape; the
// compiler monomorphises the impl body per call shape and emits a
// dedicated `__invoke` `callconv(.c)` trampoline + Block literal
// (via `#insert build_block_convert($args, $R);`).
//
// This test exercises a closure shape (`Closure(i64, i64) -> void`)
// that has NO hand-rolled `Into(Block)` impl in
// `library/modules/ffi/objc_block.sx`. Before step 5.2 lands,
// `xx cl : Block` errors out with the "no Into(Block) for
// cl_i64_i64__void" focused diagnostic. After the generic impl
// lands, the same call resolves through the pack-shaped impl and
// the per-shape trampoline ferries control back to the sx closure.
//
// The block is invoked directly through `b.invoke` (a typed
// `callconv(.c)` fn-pointer) — the same shape the Apple Block
// runtime calls when a UIKit/Foundation API hands the block back
// to its registered invoke.

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

g_a: i64 = 0;
g_b: i64 = 0;

main :: () -> i32 {
    cl := (a: i64, b: i64) => { g_a = a; g_b = b; };
    blk : Block = xx cl;

    invoke_fn : (*Block, i64, i64) -> void callconv(.c) = xx blk.invoke;
    invoke_fn(@blk, 10, 20);

    if g_a != 10 { print("FAIL: g_a={}\n", g_a); return 1; }
    if g_b != 20 { print("FAIL: g_b={}\n", g_b); return 1; }
    print("generic-into-block ok: a={} b={}\n", g_a, g_b);
    0
}