Signal API: simplify connect* usage

godot-codegen/src/generator/signals.rs

@@ -120,9 +120,9 @@ fn make_with_signals_impl(
 
             // During construction, C = Self.
             #[doc(hidden)]
-            fn __signals_from_external(gd_mut: &mut Gd<Self>) -> Self::SignalCollection<'_, Self> {
+            fn __signals_from_external(gd_ref: & Gd<Self>) -> Self::SignalCollection<'_, Self> {
                 Self::SignalCollection {
-                    __internal_obj: Some(gd_mut.clone()),
+                    __internal_obj: Some(gd_ref.clone()),
                 }
             }
         }

godot-core/src/obj/gd.rs

@@ -732,7 +732,7 @@ where
     ///
     /// [`WithUserSignals::signals()`]: crate::obj::WithUserSignals::signals()
     #[cfg(since_api = "4.2")]
-    pub fn signals(&mut self) -> T::SignalCollection<'_, T> {
+    pub fn signals(&self) -> T::SignalCollection<'_, T> {
         T::__signals_from_external(self)
     }
 }

godot-core/src/obj/traits.rs

@@ -473,7 +473,7 @@ pub trait WithSignals: GodotClass + Inherits<crate::classes::Object> {
     ///
     /// Takes by reference and not value, to retain lifetime chain.
     #[doc(hidden)]
-    fn __signals_from_external(external: &mut Gd<Self>) -> Self::SignalCollection<'_, Self>;
+    fn __signals_from_external(external: &Gd<Self>) -> Self::SignalCollection<'_, Self>;
 }
 
 /// Implemented for user-defined classes with at least one `#[signal]` declaration.