Polyfill Variant Debug impl for Godot < 4.4

Author: Bromeon

godot-core/src/classes/class_runtime.rs

@@ -7,7 +7,7 @@
 
 //! Runtime checks and inspection of Godot classes.
 
-use crate::builtin::{GString, StringName, Variant};
+use crate::builtin::{GString, StringName, Variant, VariantType};
 #[cfg(debug_assertions)]
 use crate::classes::{ClassDb, Object};
 use crate::meta::CallContext;
@@ -30,11 +30,14 @@ pub(crate) fn debug_string<T: GodotClass>(
     }
 }
 
+#[cfg(since_api = "4.4")]
 pub(crate) fn debug_string_variant(
     obj: &Variant,
     f: &mut std::fmt::Formatter<'_>,
     ty: &str,
 ) -> std::fmt::Result {
+    debug_assert_eq!(obj.get_type(), VariantType::OBJECT);
+
     let id = obj
         .object_id_unchecked()
         .expect("Variant must be of type OBJECT");
@@ -58,6 +61,31 @@ pub(crate) fn debug_string_variant(
     }
 }
 
+// Polyfill for Godot < 4.4, where Variant::object_id_unchecked() is not available.
+#[cfg(before_api = "4.4")]
+pub(crate) fn debug_string_variant(
+    obj: &Variant,
+    f: &mut std::fmt::Formatter<'_>,
+    ty: &str,
+) -> std::fmt::Result {
+    debug_assert_eq!(obj.get_type(), VariantType::OBJECT);
+
+    match obj.try_to::<Gd<crate::classes::Object>>() {
+        Ok(obj) => {
+            let id = obj.instance_id(); // Guaranteed valid, since conversion would have failed otherwise.
+            let class = obj.dynamic_class_string();
+
+            // Refcount is off-by-one due to now-created Gd<T> from conversion; correct by -1.
+            let refcount = obj.maybe_refcount().map(|rc| rc.saturating_sub(1));
+
+            debug_string_inner(f, ty, id, class, refcount)
+        }
+        Err(_) => {
+            write!(f, "{ty} {{ freed obj }}")
+        }
+    }
+}
+
 fn debug_string_inner(
     f: &mut std::fmt::Formatter<'_>,
     ty: &str,