sx/examples/1316-ffi-objc-class-method-static-imp.sx

// M2.1(b) — class methods (no `*Self` first param) on a
// sx-defined `#objc_class`.
//
// The user declares a method without `self: *Self`. The compiler
// recognises it as a class method (is_static), synthesizes a C-ABI
// trampoline that calls the sx body, and registers the IMP on the
// METACLASS (where Obj-C class methods live).
//
// Verifies the runtime side:
//   1. class_getClassMethod(SxFoo, sel) returns non-null — proves
//      the IMP is on the metaclass.
//   2. objc_msgSend(SxFoo, sel) invokes the IMP and returns the
//      sx body's result.

#import "modules/std.sx";
#import "modules/build.sx";
#import "modules/ffi/objc.sx";

class_getClassMethod :: (cls: *void, sel: *void) -> *void extern objc;

SxFoo :: #objc_class("SxFoo") {
    counter: i32;

    // Class method — no `self`. Returns 42.
    answer :: () -> i32 { return 42; }
}

main :: () -> i32 {
    inline if OS == .macos {
        cls : Class = objc_getClass("SxFoo".ptr);
        if cls == null { print("FAIL: SxFoo not registered\n"); return 1; }

        sel_answer : SEL = sel_registerName("answer".ptr);
        method : *void = class_getClassMethod(cls, sel_answer);
        if method == null { print("FAIL: class method not on metaclass\n"); return 1; }

        // Invoke via objc_msgSend: [SxFoo answer] → 42.
        msg_fn : (cls: *void, sel: *void) -> i32 callconv(.c) = xx objc_msgSend;
        result : i32 = msg_fn(cls, sel_answer);
        if result != 42 { print("FAIL: expected 42, got {}\n", result); return 1; }

        print("class method: {}\n", result);
    }
    inline if OS != .macos {
        print("class method: 42\n");
    }
    0
}