Raise warning when attaching a spec with pending keyframes to a different spec.

PiperOrigin-RevId: 685677622
Change-Id: Iba522c523ebd2afe64d6ab28c6b6b4b3cd399cf8

src/user/user_model.cc

@@ -463,7 +463,7 @@ mjCModel& mjCModel::operator-=(const mjCBody& subtree) {
   }
 
   // all keyframes are now pending and they will be resized
-  StoreKeyframes();
+  StoreKeyframes(this);
   DeleteAll(keys_);
 
   // remove body from tree
@@ -3142,9 +3142,15 @@ template void mjCModel::RestoreState<mjtNum>(
 
 
 // resolve keyframe references
-void mjCModel::StoreKeyframes() {
+void mjCModel::StoreKeyframes(mjCModel* dest) {
   bool resetlists = false;
 
+  if (this != dest && !key_pending_.empty()) {
+    mju_warning(
+        "Child model has pending keyframes. They will not be namespaced correctly. "
+        "To prevent this, compile the child model before attaching it again.");
+  }
+
   // create tree lists if they are empty, occurs if an uncompiled model is attached
   if (bodies_.size() == 1 && geoms_.empty() && sites_.empty() && joints_.empty() &&
       cameras_.empty() && lights_.empty() && frames_.empty()) {
@@ -3172,7 +3178,7 @@ void mjCModel::StoreKeyframes() {
     info.ctrl = !key->spec_ctrl_.empty();
     info.mpos = !key->spec_mpos_.empty();
     info.mquat = !key->spec_mquat_.empty();
-    key_pending_.push_back(info);
+    dest->key_pending_.push_back(info);
     ResizeKeyframe(key, qpos0.data(), body_pos0.data(), body_quat0.data());
     SaveState(info.name, key->spec_qpos_.data(), key->spec_qvel_.data(),
               key->spec_act_.data(), key->spec_ctrl_.data(),

src/user/user_model.h

@@ -297,7 +297,7 @@ class mjCModel : public mjCModel_, private mjSpec {
   void MakeData(const mjModel* m, mjData** dest);
 
   // resolve keyframe references
-  void StoreKeyframes();
+  void StoreKeyframes(mjCModel* dest);
 
   // map from default class name to default class pointer
   std::unordered_map<std::string, mjCDef*> def_map;

src/user/user_objects.cc

@@ -848,7 +848,7 @@ mjCBody& mjCBody::operator+=(const mjCFrame& other) {
   mjCBody* subtree = other.body;
   other.model->prefix = other.prefix;
   other.model->suffix = other.suffix;
-  other.model->StoreKeyframes();
+  other.model->StoreKeyframes(model);
 
   // attach defaults
   if (other.model != model) {
@@ -1808,7 +1808,7 @@ mjCFrame& mjCFrame::operator=(const mjCFrame& other) {
 mjCFrame& mjCFrame::operator+=(const mjCBody& other) {
   other.model->prefix = other.prefix;
   other.model->suffix = other.suffix;
-  other.model->StoreKeyframes();
+  other.model->StoreKeyframes(model);
   other.model->prefix = "";
   other.model->suffix = "";