Ensure behaviors are compatible with an object before pasting them

Core/GDCore/Project/ObjectTools.cpp

@@ -0,0 +1,57 @@
+/*
+ * GDevelop Core
+ * Copyright 2008-2025 Florian Rival ([email protected]). All rights
+ * reserved. This project is released under the MIT License.
+ */
+#include "ObjectTools.h"
+
+#include "GDCore/Extensions/Metadata/BehaviorMetadata.h"
+#include "GDCore/Extensions/Metadata/ObjectMetadata.h"
+#include "GDCore/Extensions/Metadata/MetadataProvider.h"
+#include "GDCore/Extensions/Platform.h"
+
+namespace gd {
+
+bool ObjectTools::IsBehaviorCompatibleWithObject(
+      const gd::Platform &platform, const gd::String &objectType,
+      const gd::String &behaviorType,
+      std::unordered_set<gd::String> coveredBehaviorType) {
+  bool isBehaviorTypeAlreadyCovered =
+      !coveredBehaviorType.insert(behaviorType).second;
+  if (isBehaviorTypeAlreadyCovered) {
+    return true;
+  }
+  const gd::BehaviorMetadata &behaviorMetadata =
+      MetadataProvider::GetBehaviorMetadata(platform, behaviorType);
+  if (MetadataProvider::IsBadBehaviorMetadata(behaviorMetadata)) {
+    // Should not happen because the behavior was added successfully (so its
+    // metadata are valid) - but double check anyway and bail out if the
+    // behavior metadata are invalid.
+    return false;
+  }
+  if (!behaviorMetadata.GetObjectType().empty() &&
+      behaviorMetadata.GetObjectType() != objectType) {
+    return false;
+  }
+  for (const gd::String &requiredBehaviorType :
+       behaviorMetadata.GetRequiredBehaviorTypes()) {
+    const gd::BehaviorMetadata &requiredBehaviorMetadata =
+        gd::MetadataProvider::GetBehaviorMetadata(platform, requiredBehaviorType);
+    if (requiredBehaviorMetadata.IsHidden()) {
+      const gd::ObjectMetadata &objectMetadata =
+          gd::MetadataProvider::GetObjectMetadata(platform, objectType);
+      if (objectMetadata.GetDefaultBehaviors().find(requiredBehaviorType) ==
+          objectMetadata.GetDefaultBehaviors().end()) {
+        // A capability is missing in the object.
+        return false;
+      }
+    }
+    if (!gd::ObjectTools::IsBehaviorCompatibleWithObject(
+            platform, objectType, requiredBehaviorType, coveredBehaviorType)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+} // namespace gd

Core/GDCore/Project/ObjectTools.h

@@ -0,0 +1,35 @@
+/*
+ * GDevelop Core
+ * Copyright 2008-2025 Florian Rival ([email protected]). All rights
+ * reserved. This project is released under the MIT License.
+ */
+#pragma once
+
+#include "GDCore/String.h"
+#include <unordered_set>
+
+namespace gd {
+class Platform;
+class Object;
+} // namespace gd
+
+namespace gd {
+
+class GD_CORE_API ObjectTools {
+public:
+  static bool IsBehaviorCompatibleWithObject(const gd::Platform &platform,
+                                             const gd::String &objectType,
+                                             const gd::String &behaviorType) {
+    std::unordered_set<gd::String> coveredBehaviorType;
+    return IsBehaviorCompatibleWithObject(platform, objectType, behaviorType,
+                                   coveredBehaviorType);
+  }
+
+private:
+  static bool IsBehaviorCompatibleWithObject(
+      const gd::Platform &platform, const gd::String &objectType,
+      const gd::String &behaviorType,
+      std::unordered_set<gd::String> coveredBehaviorType);
+};
+
+} // namespace gd

GDevelop.js/Bindings/Bindings.idl

@@ -2786,6 +2786,13 @@ interface WholeProjectRefactorer {
     [Value] SetString STATIC_FindAllLeaderboardIds([Ref] Project project);
 };
 
+interface ObjectTools {
+    boolean STATIC_IsBehaviorCompatibleWithObject(
+        [Const, Ref] Platform platform,
+        [Const] DOMString objectType,
+        [Const] DOMString behaviorType);
+};
+
 interface EventsBasedObjectDependencyFinder {
   boolean STATIC_IsDependentFromEventsBasedObject(
     [Const, Ref] Project project,

GDevelop.js/Bindings/Wrapper.cpp

@@ -77,6 +77,7 @@
 #include <GDCore/Project/MeasurementUnitElement.h>
 #include <GDCore/Project/NamedPropertyDescriptor.h>
 #include <GDCore/Project/Object.h>
+#include <GDCore/Project/ObjectTools.h>
 #include <GDCore/Project/ObjectFolderOrObject.h>
 #include <GDCore/Project/ObjectConfiguration.h>
 #include <GDCore/Project/Project.h>
@@ -658,6 +659,7 @@ typedef ExtensionAndMetadata<ExpressionMetadata> ExtensionAndExpressionMetadata;
 #define STATIC_FindInvalidRequiredBehaviorProperties \
   FindInvalidRequiredBehaviorProperties
 #define STATIC_GetBehaviorsWithType GetBehaviorsWithType
+#define STATIC_IsBehaviorCompatibleWithObject IsBehaviorCompatibleWithObject
 #define STATIC_FixInvalidRequiredBehaviorProperties \
   FixInvalidRequiredBehaviorProperties
 #define STATIC_RemoveLayerInScene RemoveLayerInScene

GDevelop.js/types.d.ts

@@ -1985,6 +1985,10 @@ export class WholeProjectRefactorer extends EmscriptenObject {
   static findAllLeaderboardIds(project: Project): SetString;
 }
 
+export class ObjectTools extends EmscriptenObject {
+  static isBehaviorCompatibleWithObject(platform: Platform, objectType: string, behaviorType: string): boolean;
+}
+
 export class EventsBasedObjectDependencyFinder extends EmscriptenObject {
   static isDependentFromEventsBasedObject(project: Project, eventsBasedObject: EventsBasedObject, dependency: EventsBasedObject): boolean;
 }

GDevelop.js/types/gdobjecttools.js

@@ -0,0 +1,6 @@
+// Automatically generated by GDevelop.js/scripts/generate-types.js
+declare class gdObjectTools {
+  static isBehaviorCompatibleWithObject(platform: gdPlatform, objectType: string, behaviorType: string): boolean;
+  delete(): void;
+  ptr: number;
+};

GDevelop.js/types/libgdevelop.js

@@ -184,6 +184,7 @@ declare class libGDevelop {
   ResourceExposer: Class<gdResourceExposer>;
   VariablesChangeset: Class<gdVariablesChangeset>;
   WholeProjectRefactorer: Class<gdWholeProjectRefactorer>;
+  ObjectTools: Class<gdObjectTools>;
   EventsBasedObjectDependencyFinder: Class<gdEventsBasedObjectDependencyFinder>;
   PropertyFunctionGenerator: Class<gdPropertyFunctionGenerator>;
   UsedExtensionsResult: Class<gdUsedExtensionsResult>;

newIDE/app/src/BehaviorsEditor/index.js

@@ -477,6 +477,15 @@ export const useManageObjectBehaviors = ({
         if (!name || !type || !serializedBehavior) {
           return;
         }
+        if (
+          !gd.ObjectTools.isBehaviorCompatibleWithObject(
+            project.getCurrentPlatform(),
+            object.getType(),
+            type
+          )
+        ) {
+          return;
+        }
 
         const behaviorMetadata = gd.MetadataProvider.getBehaviorMetadata(
           project.getCurrentPlatform(),