Merge branch 'asset-browser-grid-view' into file-browser-grid-view

7 files changed, 348 insertions, 28 deletions

diff --git a/source/blender/depsgraph/intern/builder/deg_builder_relations.cc b/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
index 3eeab23823c..0d4f9103149 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
@@ -586,11 +586,12 @@ void DepsgraphRelationBuilder::build_id(ID *id)
 
 void DepsgraphRelationBuilder::build_generic_id(ID *id)
 {
-
   if (built_map_.checkIsBuiltAndTag(id)) {
     return;
   }
 
+  const BuilderStack::ScopedEntry stack_entry = stack_.trace(*id);
+
   build_idproperties(id->properties);
   build_animdata(id);
   build_parameters(id);
@@ -621,6 +622,9 @@ void DepsgraphRelationBuilder::build_collection(LayerCollection *from_layer_coll
      * recurses into all the nested objects and collections. */
     return;
   }
+
+  const BuilderStack::ScopedEntry stack_entry = stack_.trace(collection->id);
+
   const bool group_done = built_map_.checkIsBuiltAndTag(collection);
   OperationKey object_transform_final_key(object != nullptr ? &object->id : nullptr,
                                           NodeType::TRANSFORM,
@@ -684,6 +688,9 @@ void DepsgraphRelationBuilder::build_object(Object *object)
   if (built_map_.checkIsBuiltAndTag(object)) {
     return;
   }
+
+  const BuilderStack::ScopedEntry stack_entry = stack_.trace(object->id);
+
   /* Object Transforms */
   OperationCode base_op = (object->parent) ? OperationCode::TRANSFORM_PARENT :
                                              OperationCode::TRANSFORM_LOCAL;
@@ -1133,6 +1140,9 @@ void DepsgraphRelationBuilder::build_constraints(ID *id,
     if (cti == nullptr) {
       continue;
     }
+
+    const BuilderStack::ScopedEntry stack_entry = stack_.trace(*con);
+
     /* Special case for camera tracking -- it doesn't use targets to
      * define relations. */
     /* TODO: we can now represent dependencies in a much richer manner,
@@ -1500,6 +1510,9 @@ void DepsgraphRelationBuilder::build_action(bAction *action)
   if (built_map_.checkIsBuiltAndTag(action)) {
     return;
   }
+
+  const BuilderStack::ScopedEntry stack_entry = stack_.trace(action->id);
+
   build_idproperties(action->id.properties);
   if (!BLI_listbase_is_empty(&action->curves)) {
     TimeSourceKey time_src_key;
@@ -1787,6 +1800,9 @@ void DepsgraphRelationBuilder::build_world(World *world)
   if (built_map_.checkIsBuiltAndTag(world)) {
     return;
   }
+
+  const BuilderStack::ScopedEntry stack_entry = stack_.trace(world->id);
+
   build_idproperties(world->id.properties);
   /* animation */
   build_animdata(&world->id);
@@ -2012,6 +2028,9 @@ void DepsgraphRelationBuilder::build_particle_settings(ParticleSettings *part)
   if (built_map_.checkIsBuiltAndTag(part)) {
     return;
   }
+
+  const BuilderStack::ScopedEntry stack_entry = stack_.trace(part->id);
+
   /* Animation data relations. */
   build_animdata(&part->id);
   build_parameters(&part->id);
@@ -2070,6 +2089,9 @@ void DepsgraphRelationBuilder::build_shapekeys(Key *key)
   if (built_map_.checkIsBuiltAndTag(key)) {
     return;
   }
+
+  const BuilderStack::ScopedEntry stack_entry = stack_.trace(key->id);
+
   build_idproperties(key->id.properties);
   /* Attach animdata to geometry. */
   build_animdata(&key->id);
@@ -2131,6 +2153,8 @@ void DepsgraphRelationBuilder::build_object_data_geometry(Object *object)
     LISTBASE_FOREACH (ModifierData *, md, &object->modifiers) {
       const ModifierTypeInfo *mti = BKE_modifier_get_info((ModifierType)md->type);
       if (mti->updateDepsgraph) {
+        const BuilderStack::ScopedEntry stack_entry = stack_.trace(*md);
+
         DepsNodeHandle handle = create_node_handle(obdata_ubereval_key);
         ctx.node = reinterpret_cast<::DepsNodeHandle *>(&handle);
         mti->updateDepsgraph(md, &ctx);
@@ -2251,6 +2275,9 @@ void DepsgraphRelationBuilder::build_object_data_geometry_datablock(ID *obdata)
   if (built_map_.checkIsBuiltAndTag(obdata)) {
     return;
   }
+
+  const BuilderStack::ScopedEntry stack_entry = stack_.trace(*obdata);
+
   build_idproperties(obdata->properties);
   /* Animation. */
   build_animdata(obdata);
@@ -2369,6 +2396,9 @@ void DepsgraphRelationBuilder::build_armature(bArmature *armature)
   if (built_map_.checkIsBuiltAndTag(armature)) {
     return;
   }
+
+  const BuilderStack::ScopedEntry stack_entry = stack_.trace(armature->id);
+
   build_idproperties(armature->id.properties);
   build_animdata(&armature->id);
   build_parameters(&armature->id);
@@ -2388,6 +2418,9 @@ void DepsgraphRelationBuilder::build_camera(Camera *camera)
   if (built_map_.checkIsBuiltAndTag(camera)) {
     return;
   }
+
+  const BuilderStack::ScopedEntry stack_entry = stack_.trace(camera->id);
+
   build_idproperties(camera->id.properties);
   build_animdata(&camera->id);
   build_parameters(&camera->id);
@@ -2405,6 +2438,9 @@ void DepsgraphRelationBuilder::build_light(Light *lamp)
   if (built_map_.checkIsBuiltAndTag(lamp)) {
     return;
   }
+
+  const BuilderStack::ScopedEntry stack_entry = stack_.trace(lamp->id);
+
   build_idproperties(lamp->id.properties);
   build_animdata(&lamp->id);
   build_parameters(&lamp->id);
@@ -2469,6 +2505,9 @@ void DepsgraphRelationBuilder::build_nodetree(bNodeTree *ntree)
   if (built_map_.checkIsBuiltAndTag(ntree)) {
     return;
   }
+
+  const BuilderStack::ScopedEntry stack_entry = stack_.trace(ntree->id);
+
   build_idproperties(ntree->id.properties);
   build_animdata(&ntree->id);
   build_parameters(&ntree->id);
@@ -2574,6 +2613,9 @@ void DepsgraphRelationBuilder::build_material(Material *material)
   if (built_map_.checkIsBuiltAndTag(material)) {
     return;
   }
+
+  const BuilderStack::ScopedEntry stack_entry = stack_.trace(material->id);
+
   build_idproperties(material->id.properties);
   /* animation */
   build_animdata(&material->id);
@@ -2610,6 +2652,9 @@ void DepsgraphRelationBuilder::build_texture(Tex *texture)
   if (built_map_.checkIsBuiltAndTag(texture)) {
     return;
   }
+
+  const BuilderStack::ScopedEntry stack_entry = stack_.trace(texture->id);
+
   /* texture itself */
   ComponentKey texture_key(&texture->id, NodeType::GENERIC_DATABLOCK);
   build_idproperties(texture->id.properties);
@@ -2651,6 +2696,9 @@ void DepsgraphRelationBuilder::build_image(Image *image)
   if (built_map_.checkIsBuiltAndTag(image)) {
     return;
   }
+
+  const BuilderStack::ScopedEntry stack_entry = stack_.trace(image->id);
+
   build_idproperties(image->id.properties);
   build_parameters(&image->id);
 }
@@ -2660,6 +2708,9 @@ void DepsgraphRelationBuilder::build_cachefile(CacheFile *cache_file)
   if (built_map_.checkIsBuiltAndTag(cache_file)) {
     return;
   }
+
+  const BuilderStack::ScopedEntry stack_entry = stack_.trace(cache_file->id);
+
   build_idproperties(cache_file->id.properties);
   /* Animation. */
   build_animdata(&cache_file->id);
@@ -2689,6 +2740,9 @@ void DepsgraphRelationBuilder::build_mask(Mask *mask)
   if (built_map_.checkIsBuiltAndTag(mask)) {
     return;
   }
+
+  const BuilderStack::ScopedEntry stack_entry = stack_.trace(mask->id);
+
   ID *mask_id = &mask->id;
   build_idproperties(mask_id->properties);
   /* F-Curve animation. */
@@ -2727,6 +2781,8 @@ void DepsgraphRelationBuilder::build_freestyle_linestyle(FreestyleLineStyle *lin
     return;
   }
 
+  const BuilderStack::ScopedEntry stack_entry = stack_.trace(linestyle->id);
+
   ID *linestyle_id = &linestyle->id;
   build_parameters(linestyle_id);
   build_idproperties(linestyle_id->properties);
@@ -2739,6 +2795,9 @@ void DepsgraphRelationBuilder::build_movieclip(MovieClip *clip)
   if (built_map_.checkIsBuiltAndTag(clip)) {
     return;
   }
+
+  const BuilderStack::ScopedEntry stack_entry = stack_.trace(clip->id);
+
   /* Animation. */
   build_idproperties(clip->id.properties);
   build_animdata(&clip->id);
@@ -2750,6 +2809,9 @@ void DepsgraphRelationBuilder::build_lightprobe(LightProbe *probe)
   if (built_map_.checkIsBuiltAndTag(probe)) {
     return;
   }
+
+  const BuilderStack::ScopedEntry stack_entry = stack_.trace(probe->id);
+
   build_idproperties(probe->id.properties);
   build_animdata(&probe->id);
   build_parameters(&probe->id);
@@ -2760,6 +2822,9 @@ void DepsgraphRelationBuilder::build_speaker(Speaker *speaker)
   if (built_map_.checkIsBuiltAndTag(speaker)) {
     return;
   }
+
+  const BuilderStack::ScopedEntry stack_entry = stack_.trace(speaker->id);
+
   build_idproperties(speaker->id.properties);
   build_animdata(&speaker->id);
   build_parameters(&speaker->id);
@@ -2776,6 +2841,9 @@ void DepsgraphRelationBuilder::build_sound(bSound *sound)
   if (built_map_.checkIsBuiltAndTag(sound)) {
     return;
   }
+
+  const BuilderStack::ScopedEntry stack_entry = stack_.trace(sound->id);
+
   build_idproperties(sound->id.properties);
   build_animdata(&sound->id);
   build_parameters(&sound->id);
@@ -2786,6 +2854,9 @@ void DepsgraphRelationBuilder::build_simulation(Simulation *simulation)
   if (built_map_.checkIsBuiltAndTag(simulation)) {
     return;
   }
+
+  const BuilderStack::ScopedEntry stack_entry = stack_.trace(simulation->id);
+
   build_idproperties(simulation->id.properties);
   build_animdata(&simulation->id);
   build_parameters(&simulation->id);
@@ -2850,6 +2921,9 @@ void DepsgraphRelationBuilder::build_scene_sequencer(Scene *scene)
   if (built_map_.checkIsBuiltAndTag(scene, BuilderMap::TAG_SCENE_SEQUENCER)) {
     return;
   }
+
+  /* TODO(sergey): Trace as a scene sequencer. */
+
   build_scene_audio(scene);
   ComponentKey scene_audio_key(&scene->id, NodeType::AUDIO);
   /* Make sure dependencies from sequences data goes to the sequencer evaluation. */
@@ -2893,6 +2967,9 @@ void DepsgraphRelationBuilder::build_vfont(VFont *vfont)
   if (built_map_.checkIsBuiltAndTag(vfont)) {
     return;
   }
+
+  const BuilderStack::ScopedEntry stack_entry = stack_.trace(vfont->id);
+
   build_parameters(&vfont->id);
   build_idproperties(vfont->id.properties);
 }
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_relations.h b/source/blender/depsgraph/intern/builder/deg_builder_relations.h
index 1ccecc9a3f2..64bdd2334d8 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_relations.h
+++ b/source/blender/depsgraph/intern/builder/deg_builder_relations.h
@@ -23,6 +23,7 @@
 #include "intern/builder/deg_builder.h"
 #include "intern/builder/deg_builder_map.h"
 #include "intern/builder/deg_builder_rna.h"
+#include "intern/builder/deg_builder_stack.h"
 #include "intern/depsgraph.h"
 #include "intern/node/deg_node.h"
 #include "intern/node/deg_node_component.h"
@@ -363,6 +364,7 @@ class DepsgraphRelationBuilder : public DepsgraphBuilder {
 
   BuilderMap built_map_;
   RNANodeQuery rna_node_query_;
+  BuilderStack stack_;
 };
 
 struct DepsNodeHandle {
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_relations_impl.h b/source/blender/depsgraph/intern/builder/deg_builder_relations_impl.h
index 5cbd8c8dd75..aba4a011e72 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_relations_impl.h
+++ b/source/blender/depsgraph/intern/builder/deg_builder_relations_impl.h
@@ -9,6 +9,8 @@
 
 #include "intern/node/deg_node_id.h"
 
+#include <iostream>
+
 #include "DNA_ID.h"
 #include "DNA_object_types.h"
 #include "DNA_rigidbody_types.h"
@@ -33,37 +35,30 @@ Relation *DepsgraphRelationBuilder::add_relation(const KeyFrom &key_from,
   Node *node_to = get_node(key_to);
   OperationNode *op_from = node_from ? node_from->get_exit_operation() : nullptr;
   OperationNode *op_to = node_to ? node_to->get_entry_operation() : nullptr;
+
   if (op_from && op_to) {
     return add_operation_relation(op_from, op_to, description, flags);
   }
-  else {
-    if (!op_from) {
-      /* XXX TODO: handle as error or report if needed. */
-      fprintf(stderr,
-              "add_relation(%s) - Could not find op_from (%s)\n",
-              description,
-              key_from.identifier().c_str());
-    }
-    else {
-      fprintf(stderr,
-              "add_relation(%s) - Failed, but op_from (%s) was ok\n",
-              description,
-              key_from.identifier().c_str());
-    }
-    if (!op_to) {
-      /* XXX TODO: handle as error or report if needed. */
-      fprintf(stderr,
-              "add_relation(%s) - Could not find op_to (%s)\n",
-              description,
-              key_to.identifier().c_str());
-    }
-    else {
-      fprintf(stderr,
-              "add_relation(%s) - Failed, but op_to (%s) was ok\n",
-              description,
-              key_to.identifier().c_str());
-    }
+
+  /* TODO(sergey): Report error in the interface. */
+
+  std::cerr << "--------------------------------------------------------------------\n";
+  std::cerr << "Failed to add relation \"" << description << "\"\n";
+
+  if (!op_from) {
+    std::cerr << "Could not find op_from: " << key_from.identifier() << "\n";
+  }
+
+  if (!op_to) {
+    std::cerr << "Could not find op_to: " << key_to.identifier() << "\n";
   }
+
+  if (!stack_.is_empty()) {
+    std::cerr << "\nTrace:\n\n";
+    stack_.print_backtrace(std::cerr);
+    std::cerr << "\n";
+  }
+
   return nullptr;
 }
 
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_relations_rig.cc b/source/blender/depsgraph/intern/builder/deg_builder_relations_rig.cc
index 65cf0e7d9df..2e491cd37a6 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_relations_rig.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_relations_rig.cc
@@ -322,7 +322,11 @@ void DepsgraphRelationBuilder::build_rig(Object *object)
   RootPChanMap root_map;
   bool pose_depends_on_local_transform = false;
   LISTBASE_FOREACH (bPoseChannel *, pchan, &object->pose->chanbase) {
+    const BuilderStack::ScopedEntry stack_entry = stack_.trace(*pchan);
+
     LISTBASE_FOREACH (bConstraint *, con, &pchan->constraints) {
+      const BuilderStack::ScopedEntry stack_entry = stack_.trace(*con);
+
       switch (con->type) {
         case CONSTRAINT_TYPE_KINEMATIC:
           build_ik_pose(object, pchan, con, &root_map);
@@ -356,6 +360,8 @@ void DepsgraphRelationBuilder::build_rig(Object *object)
   }
   /* Links between operations for each bone. */
   LISTBASE_FOREACH (bPoseChannel *, pchan, &object->pose->chanbase) {
+    const BuilderStack::ScopedEntry stack_entry = stack_.trace(*pchan);
+
     build_idproperties(pchan->prop);
     OperationKey bone_local_key(
         &object->id, NodeType::BONE, pchan->name, OperationCode::BONE_LOCAL);
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_relations_scene.cc b/source/blender/depsgraph/intern/builder/deg_builder_relations_scene.cc
index cdb7361afc0..cd1917cb607 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_relations_scene.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_relations_scene.cc
@@ -36,6 +36,9 @@ void DepsgraphRelationBuilder::build_scene_parameters(Scene *scene)
   if (built_map_.checkIsBuiltAndTag(scene, BuilderMap::TAG_PARAMETERS)) {
     return;
   }
+
+  /* TODO(sergey): Trace as a scene parameters. */
+
   build_idproperties(scene->id.properties);
   build_parameters(&scene->id);
   OperationKey parameters_eval_key(
@@ -56,6 +59,9 @@ void DepsgraphRelationBuilder::build_scene_compositor(Scene *scene)
   if (scene->nodetree == nullptr) {
     return;
   }
+
+  /* TODO(sergey): Trace as a scene compositor. */
+
   build_nodetree(scene->nodetree);
 }
 
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_stack.cc b/source/blender/depsgraph/intern/builder/deg_builder_stack.cc
new file mode 100644
index 00000000000..de0a5198a8a
--- /dev/null
+++ b/source/blender/depsgraph/intern/builder/deg_builder_stack.cc
@@ -0,0 +1,94 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later
+ * Copyright 2022 Blender Foundation. All rights reserved. */
+
+/** \file
+ * \ingroup depsgraph
+ */
+
+#include "intern/builder/deg_builder_stack.h"
+
+#include <iomanip>
+#include <ios>
+#include <iostream>
+
+#include "BKE_idtype.h"
+
+#include "DNA_ID.h"
+#include "DNA_action_types.h"
+#include "DNA_constraint_types.h"
+#include "DNA_modifier_types.h"
+
+namespace blender::deg {
+
+/* Spacing between adjacent columns, in number of spaces. */
+constexpr int kColumnSpacing = 4;
+
+/* Width of table columns including column padding.
+ * The type column width is a guesstimate based on "Particle Settings" with some extra padding. */
+constexpr int kPrintDepthWidth = 5 + kColumnSpacing;
+constexpr int kPrintTypeWidth = 21 + kColumnSpacing;
+
+namespace {
+
+/* NOTE: Depth column printing is already taken care of. */
+
+void print(std::ostream &stream, const ID *id)
+{
+  const IDTypeInfo *id_type_info = BKE_idtype_get_info_from_id(id);
+  stream << std::setw(kPrintTypeWidth) << id_type_info->name << (id->name + 2) << "\n";
+}
+
+void print(std::ostream &stream, const bConstraint *constraint)
+{
+  stream << std::setw(kPrintTypeWidth) << ("Constraint") << constraint->name << "\n";
+}
+
+void print(std::ostream &stream, const ModifierData *modifier_data)
+{
+  stream << std::setw(kPrintTypeWidth) << ("Modifier") << modifier_data->name << "\n";
+}
+
+void print(std::ostream &stream, const bPoseChannel *pchan)
+{
+  stream << std::setw(kPrintTypeWidth) << ("Pose Channel") << pchan->name << "\n";
+}
+
+}  // namespace
+
+void BuilderStack::print_backtrace(std::ostream &stream)
+{
+  const std::ios_base::fmtflags old_flags(stream.flags());
+
+  stream << std::left;
+
+  stream << std::setw(kPrintDepthWidth) << "Depth" << std::setw(kPrintTypeWidth) << "Type"
+         << "Name"
+         << "\n";
+
+  stream << std::setw(kPrintDepthWidth) << "-----" << std::setw(kPrintTypeWidth) << "----"
+         << "----"
+         << "\n";
+
+  int depth = 1;
+  for (const Entry &entry : stack_) {
+    stream << std::setw(kPrintDepthWidth) << depth;
+    ++depth;
+
+    if (entry.id_ != nullptr) {
+      print(stream, entry.id_);
+    }
+    else if (entry.constraint_ != nullptr) {
+      print(stream, entry.constraint_);
+    }
+    else if (entry.modifier_data_ != nullptr) {
+      print(stream, entry.modifier_data_);
+    }
+    else if (entry.pchan_ != nullptr) {
+      print(stream, entry.pchan_);
+    }
+  }
+
+  stream.flags(old_flags);
+}
+
+}  // namespace blender::deg
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_stack.h b/source/blender/depsgraph/intern/builder/deg_builder_stack.h
new file mode 100644
index 00000000000..3f9cc83928a
--- /dev/null
+++ b/source/blender/depsgraph/intern/builder/deg_builder_stack.h
@@ -0,0 +1,140 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later
+ * Copyright 2022 Blender Foundation. All rights reserved. */
+
+/** \file
+ * \ingroup depsgraph
+ */
+
+#pragma once
+
+#include "BLI_utildefines.h"
+#include "BLI_vector.hh"
+
+struct ID;
+struct bConstraint;
+struct bPoseChannel;
+struct ModifierData;
+
+namespace blender::deg {
+
+/* This class keeps track of the builder calls nesting, allowing to unroll them back and provide a
+ * clue about how the builder made it to its current state.
+ *
+ * The tracing is based on the builder giving a trace clues to the stack. Typical usage is:
+ *
+ *   void DepsgraphRelationBuilder::my_id_builder(ID *id)
+ *   {
+ *     if (built_map_.checkIsBuiltAndTag(id)) {
+ *       return;
+ *     }
+ *
+ *     const BuilderStack::ScopedEntry stack_entry = stack_.trace(*id);
+ *
+ *     ...
+ *   }
+ */
+class BuilderStack {
+ public:
+  /* Entry of the backtrace.
+   * A cheap-to-construct wrapper which allows to gather a proper string representation whenever
+   * the stack is printed. */
+  class Entry {
+   public:
+    explicit Entry(const ID &id) : id_(&id)
+    {
+    }
+
+    explicit Entry(const bConstraint &constraint) : constraint_(&constraint)
+    {
+    }
+
+    explicit Entry(const bPoseChannel &pchan) : pchan_(&pchan)
+    {
+    }
+
+    explicit Entry(const ModifierData &modifier_data) : modifier_data_(&modifier_data)
+    {
+    }
+
+   private:
+    friend class BuilderStack;
+
+    const ID *id_ = nullptr;
+    const bConstraint *constraint_ = nullptr;
+    const ModifierData *modifier_data_ = nullptr;
+    const bPoseChannel *pchan_ = nullptr;
+  };
+
+  using Stack = Vector<Entry>;
+
+  /* A helper class to provide a RAII style of tracing. It is constructed by the
+   * `BuilderStack::trace` (which pushes entry to the stack), and upon destruction of this object
+   * the corresponding entry is popped from the stack.
+   *
+   * The goal of this `ScopedEntry` is to free developers from worrying about removing entries from
+   * the stack whenever leaving a builder step scope. */
+  class ScopedEntry {
+   public:
+    /* Delete copy constructor and operator: scoped entries are only supposed to be constructed
+     * once and never copied. */
+    ScopedEntry(const ScopedEntry &other) = delete;
+    ScopedEntry &operator=(const ScopedEntry &other) = delete;
+
+    /* Move semantic. */
+    ScopedEntry(ScopedEntry &&other) noexcept : stack_(other.stack_)
+    {
+      other.stack_ = nullptr;
+    }
+    ScopedEntry &operator=(ScopedEntry &&other)
+    {
+      if (this == &other) {
+        return *this;
+      }
+
+      stack_ = other.stack_;
+      other.stack_ = nullptr;
+
+      return *this;
+    }
+
+    ~ScopedEntry()
+    {
+      /* Stack will become nullptr when the entry was moved somewhere else. */
+      if (stack_ != nullptr) {
+        BLI_assert(!stack_->is_empty());
+        stack_->pop_last();
+      }
+    }
+
+   private:
+    friend BuilderStack;
+
+    explicit ScopedEntry(Stack &stack) : stack_(&stack)
+    {
+    }
+
+    Stack *stack_;
+  };
+
+  BuilderStack() = default;
+  ~BuilderStack() = default;
+
+  bool is_empty() const
+  {
+    return stack_.is_empty();
+  }
+
+  void print_backtrace(std::ostream &stream);
+
+  template<class... Args> ScopedEntry trace(const Args &...args)
+  {
+    stack_.append_as(args...);
+
+    return ScopedEntry(stack_);
+  }
+
+ private:
+  Stack stack_;
+};
+
+}  // namespace blender::deg