Remove special-case for using () when there are no ivars

This means that users have to write the slightly more verbose
`.set_ivars(Ivars::<Self> {})` instead of `.set_ivars(())`.

This is probably fine, we should instead find better ways to avoid such
situations in the first place, such as by using derive macros, see
#267.

Author: madsmtm

crates/objc2/src/__macros/define_class/ivars.rs

@@ -516,7 +516,7 @@ mod tests {
             impl ImplsDrop {
                 #[unsafe(method_id(init))]
                 fn init(this: Allocated<Self>) -> Option<Retained<Self>> {
-                    unsafe { msg_send![super(this.set_ivars(())), init] }
+                    unsafe { msg_send![super(this.set_ivars(Ivars::<Self> {})), init] }
                 }
             }
         );
@@ -533,7 +533,7 @@ mod tests {
         let _ = unsafe { init_only_superclasses(ImplsDrop::alloc()) };
         check([]);
 
-        let _ = unsafe { init_no_finalize(ImplsDrop::alloc(), ()) };
+        let _ = unsafe { init_no_finalize(ImplsDrop::alloc(), Ivars::<ImplsDrop> {}) };
         check([]);
 
         let _ = unsafe { init(ImplsDrop::alloc()) };
@@ -877,7 +877,7 @@ mod tests {
             }
         }
 
-        let obj = DropPanics::alloc().set_ivars(());
+        let obj = DropPanics::alloc().set_ivars(Ivars::<DropPanics> {});
         let obj: Retained<DropPanics> = unsafe { msg_send![super(obj), init] };
         drop(obj);
     }
@@ -937,7 +937,7 @@ mod tests {
             }
         }
 
-        let obj = DropRetainsAndLeaksSelf::alloc().set_ivars(());
+        let obj = DropRetainsAndLeaksSelf::alloc().set_ivars(Ivars::<DropRetainsAndLeaksSelf> {});
         let obj: Retained<DropRetainsAndLeaksSelf> = unsafe { msg_send![super(obj), init] };
         drop(obj);
 

crates/objc2/src/__macros/define_class/mod.rs

@@ -726,10 +726,9 @@ macro_rules! __define_class_inner {
             $crate::__define_class_ivar_accessors!(($class) $($ivars)*);
 
             impl $crate::DefinedClass for $class {
-                type Ivars = $crate::__define_class_ivars_type!(
-                    (__Objc2IvarsContainer)
-                    $($ivars)*
-                );
+                // NOTE: We could have used `()` here when there are no ivars,
+                // but it's more consistent to always use the container.
+                type Ivars = __Objc2IvarsContainer;
 
                 #[inline]
                 fn __ivars_offset() -> $crate::__macros::isize {
@@ -1016,17 +1015,3 @@ macro_rules! __define_class_ivar_accessors {
         ));
     }
 }
-
-#[doc(hidden)]
-#[macro_export]
-macro_rules! __define_class_ivars_type {
-    (($ivars_ty:ident)) => {
-        // Default to `Ivars = ()` when no ivars are specified.
-        //
-        // We might remove this in the future, but let's keep it for now.
-        ()
-    };
-    (($ivars_ty:ident) $($t:tt)*) => {
-        $ivars_ty
-    };
-}

crates/objc2/src/__macros/msg_send/retained.rs

@@ -320,7 +320,7 @@ mod tests {
 
     use crate::rc::{autoreleasepool, Allocated, PartialInit, RcTestObject, ThreadTestData};
     use crate::runtime::{AnyObject, NSObject, NSObjectProtocol, NSZone};
-    use crate::{class, define_class, extern_methods, msg_send, AnyThread};
+    use crate::{class, define_class, extern_methods, msg_send, AnyThread, Ivars};
 
     #[test]
     fn test_send_message_manuallydrop() {
@@ -616,7 +616,7 @@ mod tests {
         expected.drop += 1;
         expected.assert_current();
 
-        let obj = RcTestObject::alloc().set_ivars(());
+        let obj = RcTestObject::alloc().set_ivars(Ivars::<RcTestObject> {});
         let _: Retained<RcTestObject> = unsafe { msg_send![super(obj), init] };
         expected.alloc += 1;
         expected.release += 1;
@@ -658,7 +658,7 @@ mod tests {
         ignore = "SIGSEGVs with the old runtime for some reason?"
     )]
     fn test_super_init_not_initialized() {
-        let obj = RcTestObject::alloc().set_ivars(());
+        let obj = RcTestObject::alloc().set_ivars(Ivars::<RcTestObject> {});
         let _: Retained<RcTestObject> =
             unsafe { msg_send![super(obj, RcTestObject::class()), init] };
     }

crates/objc2/src/rc/allocated_partial_init.rs

@@ -361,6 +361,7 @@ mod tests {
     use super::*;
     use crate::rc::RcTestObject;
     use crate::runtime::NSObject;
+    use crate::Ivars;
 
     #[test]
     fn auto_traits() {
@@ -396,7 +397,7 @@ mod tests {
     fn test_set_ivars_null() {
         // SAFETY: The pointer is NULL
         let obj: Allocated<RcTestObject> = unsafe { Allocated::new(ptr::null_mut()) };
-        let _ = obj.set_ivars(());
+        let _ = obj.set_ivars(Ivars::<RcTestObject> {});
     }
 
     #[test]

crates/objc2/src/rc/test_object.rs

@@ -4,7 +4,7 @@ use core::ptr;
 
 use crate::rc::{Allocated, DefaultRetained, Retained};
 use crate::runtime::{NSObject, NSObjectProtocol, NSZone};
-use crate::{define_class, msg_send, ClassType};
+use crate::{define_class, msg_send, ClassType, Ivars};
 
 // TODO: Put tests that use this in another crate
 #[derive(Debug, Clone, Default, PartialEq, Eq)]
@@ -108,7 +108,7 @@ define_class!(
         #[unsafe(method_id(init))]
         unsafe fn init(this: Allocated<Self>) -> Retained<Self> {
             TEST_DATA.with(|data| data.borrow_mut().init += 1);
-            let this = this.set_ivars(());
+            let this = this.set_ivars(Ivars::<RcTestObject> {});
             unsafe { msg_send![super(this), init] }
         }
 

crates/objc2/src/topics/run_loop.md

@@ -56,7 +56,6 @@ define_class!(
     #[derive(Debug)]
     struct AppDelegate {
         // Whatever state you want to store in your delegate.
-        state: i32,
     }
 
     impl AppDelegate {
@@ -66,7 +65,6 @@ define_class!(
         fn init(this: Allocated<Self>) -> Retained<Self> {
             let this = this.set_ivars(Ivars::<Self> {
                 // Initialize state.
-                state: 42,
             });
             unsafe { msg_send![super(this), init] }
         }

crates/objc2/tests/track_caller.rs

@@ -10,7 +10,7 @@ use std::sync::Mutex;
 use objc2::encode::Encode;
 use objc2::rc::{self, Allocated, Retained};
 use objc2::runtime::{self, NSObject};
-use objc2::{class, define_class, msg_send, AnyThread, ClassType};
+use objc2::{class, define_class, msg_send, AnyThread, ClassType, Ivars};
 
 #[path = "../src/rc/test_object.rs"]
 #[allow(dead_code)]

crates/test-ui/ui/implement_protocol_missing_super.stderr

@@ -1,6 +1,6 @@
 use objc2::rc::Retained;
 use objc2::runtime::AnyObject;
-use objc2::{define_class, msg_send, MainThreadMarker, MainThreadOnly};
+use objc2::{define_class, msg_send, Ivars, MainThreadMarker, MainThreadOnly};
 use objc2_app_kit::{NSResponder, NSViewController};
 use objc2_foundation::{NSObject, NSObjectProtocol};
 
@@ -40,7 +40,7 @@ impl ViewController {
     // FIXME: Make it possible to avoid this boilerplate.
     pub fn new(mtm: MainThreadMarker) -> Retained<Self> {
         let this = Self::alloc(mtm);
-        let this = this.set_ivars(());
+        let this = this.set_ivars(Ivars::<Self> {});
         // SAFETY: `ViewController` is safe to initialize.
         unsafe { msg_send![super(this), init] }
     }

examples/app/default_xcode_app/view_controller.rs

@@ -44,16 +44,13 @@ impl UIApplication {
     ///     #[derive(Debug)]
     ///     struct AppDelegate {
     ///         // Whatever state you want to store in your delegate.
-    ///         state: i32,
     ///     }
     ///
     ///     impl AppDelegate {
     ///         // Called by `UIApplication::main`.
     ///         #[unsafe(method_id(init))]
     ///         fn init(this: Allocated<Self>) -> Retained<Self> {
-    ///             let this = this.set_ivars(Ivars::<Self> {
-    ///                 state: 42,
-    ///             });
+    ///             let this = this.set_ivars(Ivars::<Self> {});
     ///             unsafe { msg_send![super(this), init] }
     ///         }
     ///     }