From 71e9d871a9a91101f5c81f6c8401c354307089ca Mon Sep 17 00:00:00 2001
From: Jan Haller <bromeon@gmail.com>
Date: Mon, 5 Aug 2024 18:15:23 +0200
Subject: [PATCH] Include class name in error message

---
 godot-core/src/obj/gd.rs                           |  8 +++++---
 godot-core/src/registry/godot_register_wrappers.rs | 13 ++++++++-----
 godot-core/src/registry/property.rs                |  9 ++++++---
 3 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/godot-core/src/obj/gd.rs b/godot-core/src/obj/gd.rs
index 1a34cb3d6..103589d3e 100644
--- a/godot-core/src/obj/gd.rs
+++ b/godot-core/src/obj/gd.rs
@@ -16,7 +16,8 @@ use crate::builtin::{Callable, NodePath, StringName, Variant};
 use crate::global::PropertyHint;
 use crate::meta::error::{ConvertError, FromFfiError};
 use crate::meta::{
-    ArrayElement, CallContext, FromGodot, GodotConvert, GodotType, PropertyHintInfo, ToGodot,
+    ArrayElement, CallContext, ClassName, FromGodot, GodotConvert, GodotType, PropertyHintInfo,
+    ToGodot,
 };
 use crate::obj::{
     bounds, cap, Bounds, EngineEnum, GdDerefTarget, GdMut, GdRef, GodotClass, Inherits, InstanceId,
@@ -824,8 +825,9 @@ where
         PropertyHintInfo { hint, hint_string }
     }
 
-    fn is_node_class() -> bool {
-        T::inherits::<classes::Node>()
+    #[doc(hidden)]
+    fn as_node_class() -> Option<ClassName> {
+        T::inherits::<classes::Node>().then(|| T::class_name())
     }
 }
 
diff --git a/godot-core/src/registry/godot_register_wrappers.rs b/godot-core/src/registry/godot_register_wrappers.rs
index 859d201c5..24a806060 100644
--- a/godot-core/src/registry/godot_register_wrappers.rs
+++ b/godot-core/src/registry/godot_register_wrappers.rs
@@ -25,11 +25,14 @@ pub fn register_export<C: GodotClass, T: Export>(
 ) {
     // Note: if the user manually specifies `hint`, `hint_string` or `usage` keys, and thus is routed to `register_var()` instead,
     // they can bypass this validation.
-    if T::is_node_class() && !C::inherits::<classes::Node>() {
-        panic!(
-            "Node export is only supported in Node-derived classes, but the current class is {}.",
-            C::class_name()
-        );
+    if !C::inherits::<classes::Node>() {
+        if let Some(class) = T::as_node_class() {
+            panic!(
+                "#[export] for Gd<{t}>: nodes can only be exported in Node-derived classes, but the current class is {c}.",
+                t = class,
+                c = C::class_name()
+            );
+        }
     }
 
     register_var::<C, T>(property_name, getter_name, setter_name, hint_info, usage);
diff --git a/godot-core/src/registry/property.rs b/godot-core/src/registry/property.rs
index c92b27f80..59ed9daf0 100644
--- a/godot-core/src/registry/property.rs
+++ b/godot-core/src/registry/property.rs
@@ -9,7 +9,7 @@
 
 use godot_ffi as sys;
 
-use crate::meta::{FromGodot, GodotConvert, GodotType, PropertyHintInfo, ToGodot};
+use crate::meta::{ClassName, FromGodot, GodotConvert, GodotType, PropertyHintInfo, ToGodot};
 
 // ----------------------------------------------------------------------------------------------------------------------------------------------
 // Trait definitions
@@ -56,9 +56,12 @@ pub trait Export: Var {
         <Self as Var>::var_hint()
     }
 
+    /// If this is a class inheriting `Node`, returns the `ClassName`; otherwise `None`.
+    ///
     /// Only overridden for `Gd<T>`, to detect erroneous exports of `Node` inside a `Resource` class.
-    fn is_node_class() -> bool {
-        false
+    #[allow(clippy::wrong_self_convention)]
+    fn as_node_class() -> Option<ClassName> {
+        None
     }
 }