sx/examples/issue-0044.sx

// issue-0044 — `xx this` inside a BOOL-returning #objc_class method
// truncated to i8 when used as an argument to a foreign-class method
// call. Root cause was resolveCallParamTypes returning an empty slice
// for foreign-class method receivers (the type was a `#foreign
// #objc_class` alias), so the per-arg target_type defaulted to the
// enclosing function's return type (BOOL → i8) and the `xx ptr` cast
// silently truncated the pointer to its low byte.
//
// Verification: every probe must round-trip the receiver pointer. A
// pre-fix compiler reads the LOW BYTE of `xx this` at the
// `addObserver:selector:name:object:` call site, so the observer
// would be e.g. 0xC0/0x20 instead of the real pointer.
#import "modules/std.sx";
#import "modules/std/objc.sx";
#import "modules/compiler.sx";

g_observer : *void = null;

// Stand-in for NSNotificationCenter — we just need a foreign-class
// method with several *void args so the call site's arg-target-type
// resolution exercises the same path as uikit.sx's keyboard observer.
SxIssue44Bus :: #foreign #objc_class("NSNotificationCenter") {
    defaultCenter :: () -> *SxIssue44Bus;
    addObserver_selector_name_object :: (self: *Self, observer: *void, sel: *void, name: *void, obj: *void);
}

SxIssue44Foo :: #objc_class("SxIssue44Foo") {
    counter: s32;
    sentinel: *void;

    alloc :: () -> *SxIssue44Foo;

    bump :: (this: *Self) {
        this.counter += 1;
    }

    get :: (this: *Self) -> s32 {
        return this.counter;
    }

    // Return the receiver — direct `xx this` round-trip.
    me :: (this: *Self) -> *void {
        return xx this;
    }

    // SxAppDelegate-shape: BOOL return + 2 extra *void args. Pre-fix,
    // the call to addObserver:... would receive `xx this` truncated to
    // its low byte (because resolveCallParamTypes returned `&.{}` for
    // foreign-class receivers and `self.target_type` leaked the BOOL
    // return type into the call's args).
    appDelegate_options :: (this: *Self, app: *void, opts: *void) -> BOOL {
        bus := SxIssue44Bus.defaultCenter();
        bus.addObserver_selector_name_object(
            xx this,
            xx 0,
            xx 0,
            null);
        return 1;
    }

    // Same shape but captures the observer-equivalent value to a global
    // so we can read it back without going through NSNotificationCenter
    // (which would crash with a real observer != NSObject subclass).
    captureSelf_options :: (this: *Self, app: *void, opts: *void) -> BOOL {
        capture_observer(xx this);
        return 1;
    }
}

capture_observer :: (p: *void) {
    g_observer = p;
}

main :: () -> s32 {
    inline if OS == .macos {
        f := SxIssue44Foo.alloc();
        if f == null { print("FAIL: alloc returned null\n"); return 1; }

        f.bump();
        f.bump();
        f.bump();
        print("counter: {}\n", f.get());

        // Direct `xx this` round-trip (worked pre-fix).
        f_void : *void = xx f;
        if f.me() == f_void {
            print("me: ok\n");
        } else {
            print("me: WRONG\n");
        }

        // The actual repro: BOOL return + foreign-class method call.
        // Pre-fix: `xx this` truncated to i8, capture_observer receives
        // (low_byte_of_f) cast back to *void, which won't equal f_void.
        g_observer = null;
        _ = f.captureSelf_options(xx 0, xx 0);
        if g_observer == f_void {
            print("captureSelf-from-BOOL: ok\n");
        } else {
            print("captureSelf-from-BOOL: WRONG\n");
        }

        // Also exercise the compile-only path — appDelegate_options' IR
        // must pass `ptr` args to objc_msgSend (not `i8`). We don't
        // dispatch this for real (would crash inside NSNotificationCenter),
        // but the build pulling cleanly through is half the point.
    }
    inline if OS != .macos { print("skipped (not macos)\n"); }
    0;
}