ConnectBuilder::connect_*_gd() takes Gd instead of &mut Gd

Accepting Gd<T> by value is the more natural signature, and the only one compatible
with #[func] methods. Would otherwise need separate functions. The occurring clone()
is a pointer copy for manually-managed objects, which make up majority of signal usage.

Author: Bromeon

godot-core/src/registry/signal/connect_builder.rs

@@ -183,6 +183,7 @@ macro_rules! impl_builder_connect {
                 F: FnMut(&mut C, $($Ps),*) -> R + 'static,
             {
                 let mut gd = self.parent_sig.receiver_object();
+
                 let godot_fn = make_godot_fn(move |($($args,)*): ($($Ps,)*)| {
                     let mut guard = Gd::bind_mut(&mut gd);
                     function(&mut *guard, $($args),*);
@@ -201,11 +202,12 @@ macro_rules! impl_builder_connect {
             /// - If you need cross-thread signals, use [`connect_sync()`](#method.connect_sync) instead (requires feature `experimental-threads`).
             pub fn connect_self_gd<F, R>(self, mut function: F)
             where
-                F: FnMut(&mut Gd<C>, $($Ps),*) -> R + 'static,
+                F: FnMut(Gd<C>, $($Ps),*) -> R + 'static,
             {
-                let mut gd = self.parent_sig.receiver_object();
+                let gd = self.parent_sig.receiver_object();
+
                 let godot_fn = make_godot_fn(move |($($args,)*): ($($Ps,)*)| {
-                    function(&mut gd, $($args),*);
+                    function(gd.clone(), $($args),*);
                 });
 
                 self.inner_connect_godot_fn::<F>(godot_fn);
@@ -253,12 +255,12 @@ macro_rules! impl_builder_connect {
             pub fn connect_other_gd<F, R, OtherC>(self, object: &impl ToSignalObj<OtherC>, mut method: F)
             where
                 OtherC: GodotClass,
-                F: FnMut(&mut Gd<OtherC>, $($Ps),*) -> R + 'static,
+                F: FnMut(Gd<OtherC>, $($Ps),*) -> R + 'static,
             {
-                let mut gd = object.to_signal_obj();
+                let gd = object.to_signal_obj();
 
                 let godot_fn = make_godot_fn(move |($($args,)*): ($($Ps,)*)| {
-                    method(&mut gd, $($args),*);
+                    method(gd.clone(), $($args),*);
                 });
 
                 self.inner_connect_godot_fn::<F>(godot_fn);

itest/rust/src/builtin_tests/containers/signal_test.rs

@@ -59,10 +59,10 @@ fn signal_symbols_internal() {
     // Check that closure is invoked.
     assert_eq!(tracker.get(), 1234, "Emit failed (closure)");
 
-    // Check that instance method is invoked.
+    // Check that instance methods self_receive() and self_receive_gd_inc1() are invoked.
     assert_eq!(
         emitter.bind().last_received_int,
-        1234,
+        1234 + 1, // self_receive_gd_inc1() increments by 1, and should be called after self_receive().
         "Emit failed (method)"
     );
 
@@ -400,7 +400,7 @@ fn signal_symbols_connect_inferred() {
         .tree_exiting()
         .builder()
         .flags(ConnectFlags::DEFERRED)
-        .connect_self_gd(|this| {
+        .connect_self_gd(|mut this| {
             // Use methods that `Node` declares.
             let _ = this.get_path(); // ref.
             this.set_unique_name_in_owner(true); // mut.
@@ -422,7 +422,7 @@ fn signal_symbols_connect_inferred() {
         .signals()
         .tree_exiting()
         .builder()
-        .connect_other_gd(&user, |this| {
+        .connect_other_gd(&user, |mut this| {
             // Use methods that `Node` declares.
             let _ = this.get_path(); // ref.
             this.set_unique_name_in_owner(true); // mut.
@@ -513,6 +513,14 @@ mod emitter {
             }
         }
 
+        #[func]
+        pub fn self_receive_gd_inc1(mut this: Gd<Self>, _arg1: i64) {
+            #[cfg(since_api = "4.2")]
+            {
+                this.bind_mut().last_received_int += 1;
+            }
+        }
+
         #[func]
         pub fn self_receive_constant(&mut self) {
             #[cfg(since_api = "4.2")]
@@ -534,6 +542,7 @@ mod emitter {
             sig.connect_self(Self::self_receive);
             sig.connect(Self::self_receive_static);
             sig.connect(move |i| tracker.set(i));
+            sig.builder().connect_self_gd(Self::self_receive_gd_inc1);
         }
 
         #[cfg(since_api = "4.2")]