add some run-pass tests for darwin-objc

Author: jbatez

tests/ui/README.md

@@ -350,6 +350,12 @@ Tests for FFI with C varargs (`va_list`).
 
 Tests for detection and handling of cyclic trait dependencies.
 
+## `tests/ui/darwin-objc/`: Darwin Objective-C
+
+Tests exercising `#![feature(darwin_objc)]`.
+
+See [Tracking Issue for `darwin_objc` #145496](https://github.com/rust-lang/rust/issues/145496).
+
 ## `tests/ui/dataflow_const_prop/`
 
 Contains a single regression test for const prop in `SwitchInt` pass crashing when `ptr2int` transmute is involved.

tests/ui/darwin-objc/darwin-objc-class-selector.rs

@@ -0,0 +1,31 @@
+// Call `[NSObject class]` using `objc::class!` and `objc::selector!`.
+
+//@ edition: 2024
+//@ only-apple
+//@ run-pass
+
+#![feature(darwin_objc)]
+
+use std::mem::transmute;
+use std::os::darwin::objc;
+
+#[link(name = "Foundation", kind = "framework")]
+unsafe extern "C" {}
+
+#[link(name = "objc", kind = "dylib")]
+unsafe extern "C" {
+    unsafe fn objc_msgSend();
+}
+
+fn main() {
+    let msg_send_fn = unsafe {
+        transmute::<
+            unsafe extern "C" fn(),
+            unsafe extern "C" fn(objc::Class, objc::SEL) -> objc::Class,
+        >(objc_msgSend)
+    };
+    let static_sel = objc::selector!("class");
+    let static_class = objc::class!("NSObject");
+    let runtime_class = unsafe { msg_send_fn(static_class, static_sel) };
+    assert_eq!(static_class, runtime_class);
+}

tests/ui/darwin-objc/darwin-objc-class.rs

@@ -0,0 +1,39 @@
+// Test that `objc::class!` returns the same thing as `objc_lookUpClass`.
+
+//@ edition: 2024
+//@ only-apple
+//@ run-pass
+
+#![feature(darwin_objc)]
+
+use std::ffi::c_char;
+use std::os::darwin::objc;
+
+#[link(name = "Foundation", kind = "framework")]
+unsafe extern "C" {}
+
+#[link(name = "objc")]
+unsafe extern "C" {
+    fn objc_lookUpClass(methname: *const c_char) -> objc::Class;
+}
+
+fn get_object_class() -> objc::Class {
+    objc::class!("NSObject")
+}
+
+fn lookup_object_class() -> objc::Class {
+    unsafe { objc_lookUpClass(c"NSObject".as_ptr()) }
+}
+
+fn get_string_class() -> objc::Class {
+    objc::class!("NSString")
+}
+
+fn lookup_string_class() -> objc::Class {
+    unsafe { objc_lookUpClass(c"NSString".as_ptr()) }
+}
+
+fn main() {
+    assert_eq!(get_object_class(), lookup_object_class());
+    assert_eq!(get_string_class(), lookup_string_class());
+}

tests/ui/darwin-objc/darwin-objc-selector.rs

@@ -0,0 +1,36 @@
+// Test that `objc::selector!` returns the same thing as `sel_registerName`.
+
+//@ edition: 2024
+//@ only-apple
+//@ run-pass
+
+#![feature(darwin_objc)]
+
+use std::ffi::c_char;
+use std::os::darwin::objc;
+
+#[link(name = "objc")]
+unsafe extern "C" {
+    fn sel_registerName(methname: *const c_char) -> objc::SEL;
+}
+
+fn get_alloc_selector() -> objc::SEL {
+    objc::selector!("alloc")
+}
+
+fn register_alloc_selector() -> objc::SEL {
+    unsafe { sel_registerName(c"alloc".as_ptr()) }
+}
+
+fn get_init_selector() -> objc::SEL {
+    objc::selector!("initWithCString:encoding:")
+}
+
+fn register_init_selector() -> objc::SEL {
+    unsafe { sel_registerName(c"initWithCString:encoding:".as_ptr()) }
+}
+
+fn main() {
+    assert_eq!(get_alloc_selector(), register_alloc_selector());
+    assert_eq!(get_init_selector(), register_init_selector());
+}