Nodes: add more flexible method to declare sockets of a node

Previously, built-in nodes had to implement "socket templates"
(`bNodeSocketTemplate`) to tell Blender which sockets they have.
It was nice that this was declarative, but this approach was way
too rigid and was cumbersome to use in many cases.

This commit starts to move us away from this rigid structure
by letting nodes implement a function that declares the sockets
the node has. Right now this is used as a direct replacement
of the "socket template" approach to keep the refactor smaller.
It's just a bit easier to read and write.

In the future we want to support more complex features like
dynamic numbers of sockets and type inferencing. Those features
will be easier to build on this new approach.

This new approach can live side by side with `bNodeSocketTemplate`
for a while. That makes it easier to update nodes one by one.

Note: In `bNodeSocketTemplate` socket identifiers were made
unique automatically. In this new approach, one has to specify
unique identifiers manually (unless the name is unique already).

Differential Revision: https://developer.blender.org/D12335

20 files changed, 1001 insertions, 143 deletions

diff --git a/source/blender/blenkernel/BKE_node.h b/source/blender/blenkernel/BKE_node.h
index 379d4332473..5e0526ab262 100644
--- a/source/blender/blenkernel/BKE_node.h
+++ b/source/blender/blenkernel/BKE_node.h
@@ -113,6 +113,7 @@ namespace blender {
 namespace nodes {
 class NodeMultiFunctionBuilder;
 class GeoNodeExecParams;
+class NodeDeclarationBuilder;
 }  // namespace nodes
 namespace fn {
 class CPPType;
@@ -122,6 +123,7 @@ class MFDataType;
 
 using NodeMultiFunctionBuildFunction = void (*)(blender::nodes::NodeMultiFunctionBuilder &builder);
 using NodeGeometryExecFunction = void (*)(blender::nodes::GeoNodeExecParams params);
+using NodeDeclareFunction = void (*)(blender::nodes::NodeDeclarationBuilder &builder);
 using SocketGetCPPTypeFunction = const blender::fn::CPPType *(*)();
 using SocketGetCPPValueFunction = void (*)(const struct bNodeSocket &socket, void *r_value);
 using SocketGetGeometryNodesCPPTypeFunction = const blender::fn::CPPType *(*)();
@@ -131,6 +133,7 @@ using SocketGetGeometryNodesCPPValueFunction = void (*)(const struct bNodeSocket
 #else
 typedef void *NodeMultiFunctionBuildFunction;
 typedef void *NodeGeometryExecFunction;
+typedef void *NodeDeclareFunction;
 typedef void *SocketGetCPPTypeFunction;
 typedef void *SocketGetGeometryNodesCPPTypeFunction;
 typedef void *SocketGetGeometryNodesCPPValueFunction;
@@ -334,6 +337,9 @@ typedef struct bNodeType {
   NodeGeometryExecFunction geometry_node_execute;
   bool geometry_node_execute_supports_laziness;
 
+  /* Declares which sockets the node has. */
+  NodeDeclareFunction declare;
+
   /* RNA integration */
   ExtensionRNA rna_ext;
 } bNodeType;
@@ -615,6 +621,10 @@ struct bNodeSocket *nodeInsertStaticSocket(struct bNodeTree *ntree,
                                            const char *identifier,
                                            const char *name);
 void nodeRemoveSocket(struct bNodeTree *ntree, struct bNode *node, struct bNodeSocket *sock);
+void nodeRemoveSocketEx(struct bNodeTree *ntree,
+                        struct bNode *node,
+                        struct bNodeSocket *sock,
+                        bool do_id_user);
 void nodeRemoveAllSockets(struct bNodeTree *ntree, struct bNode *node);
 void nodeModifySocketType(struct bNodeTree *ntree,
                           struct bNode *node,
diff --git a/source/blender/blenkernel/intern/node.cc b/source/blender/blenkernel/intern/node.cc
index fb43d1fc87f..48d747e2bf3 100644
--- a/source/blender/blenkernel/intern/node.cc
+++ b/source/blender/blenkernel/intern/node.cc
@@ -79,6 +79,7 @@
 #include "NOD_composite.h"
 #include "NOD_function.h"
 #include "NOD_geometry.h"
+#include "NOD_node_declaration.hh"
 #include "NOD_shader.h"
 #include "NOD_socket.h"
 #include "NOD_texture.h"
@@ -887,7 +888,7 @@ void ntreeBlendReadLib(struct BlendLibReader *reader, struct bNodeTree *ntree)
    * to match the static layout. */
   if (!BLO_read_lib_is_undo(reader)) {
     LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
-      node_verify_socket_templates(ntree, node);
+      node_verify_sockets(ntree, node, false);
     }
   }
 }
@@ -1011,6 +1012,13 @@ IDTypeInfo IDType_ID_NT = {
 
 static void node_add_sockets_from_type(bNodeTree *ntree, bNode *node, bNodeType *ntype)
 {
+  if (ntype->declare != nullptr) {
+    blender::nodes::NodeDeclaration node_decl;
+    blender::nodes::NodeDeclarationBuilder builder{node_decl};
+    ntype->declare(builder);
+    node_decl.build(*ntree, *node);
+    return;
+  }
   bNodeSocketTemplate *sockdef;
   /* bNodeSocket *sock; */ /* UNUSED */
 
@@ -1916,6 +1924,14 @@ static void node_socket_free(bNodeTree *UNUSED(ntree),
 
 void nodeRemoveSocket(bNodeTree *ntree, bNode *node, bNodeSocket *sock)
 {
+  nodeRemoveSocketEx(ntree, node, sock, true);
+}
+
+void nodeRemoveSocketEx(struct bNodeTree *ntree,
+                        struct bNode *node,
+                        struct bNodeSocket *sock,
+                        bool do_id_user)
+{
   LISTBASE_FOREACH_MUTABLE (bNodeLink *, link, &ntree->links) {
     if (link->fromsock == sock || link->tosock == sock) {
       nodeRemLink(ntree, link);
@@ -1926,7 +1942,7 @@ void nodeRemoveSocket(bNodeTree *ntree, bNode *node, bNodeSocket *sock)
   BLI_remlink(&node->inputs, sock);
   BLI_remlink(&node->outputs, sock);
 
-  node_socket_free(ntree, sock, node, true);
+  node_socket_free(ntree, sock, node, do_id_user);
   MEM_freeN(sock);
 
   node->update |= NODE_UPDATE;
diff --git a/source/blender/blenloader/intern/versioning_270.c b/source/blender/blenloader/intern/versioning_270.c
index 6492f0d1f69..fa15e541e43 100644
--- a/source/blender/blenloader/intern/versioning_270.c
+++ b/source/blender/blenloader/intern/versioning_270.c
@@ -291,7 +291,7 @@ static void do_version_hue_sat_node(bNodeTree *ntree, bNode *node)
   }
 
   /* Make sure new sockets are properly created. */
-  node_verify_socket_templates(ntree, node);
+  node_verify_sockets(ntree, node, false);
   /* Convert value from old storage to new sockets. */
   NodeHueSat *nhs = node->storage;
   bNodeSocket *hue = nodeFindSocket(node, SOCK_IN, "Hue"),
@@ -357,7 +357,7 @@ static void do_versions_compositor_render_passes(bNodeTree *ntree)
        */
       do_versions_compositor_render_passes_storage(node);
       /* Make sure new sockets are properly created. */
-      node_verify_socket_templates(ntree, node);
+      node_verify_sockets(ntree, node, false);
       /* Make sure all possibly created sockets have proper storage. */
       do_versions_compositor_render_passes_storage(node);
     }
diff --git a/source/blender/nodes/CMakeLists.txt b/source/blender/nodes/CMakeLists.txt
index 8dfab671565..29a1de381b5 100644
--- a/source/blender/nodes/CMakeLists.txt
+++ b/source/blender/nodes/CMakeLists.txt
@@ -347,6 +347,8 @@ set(SRC
   intern/node_exec.cc
   intern/node_geometry_exec.cc
   intern/node_multi_function.cc
+  intern/node_declaration.cc
+  intern/node_socket_declarations.cc
   intern/node_socket.cc
   intern/node_tree_ref.cc
   intern/node_util.c
@@ -367,6 +369,8 @@ set(SRC
   NOD_geometry_nodes_eval_log.hh
   NOD_math_functions.hh
   NOD_multi_function.hh
+  NOD_node_declaration.hh
+  NOD_socket_declarations.hh
   NOD_node_tree_ref.hh
   NOD_shader.h
   NOD_socket.h
diff --git a/source/blender/nodes/NOD_node_declaration.hh b/source/blender/nodes/NOD_node_declaration.hh
new file mode 100644
index 00000000000..9c461885859
--- /dev/null
+++ b/source/blender/nodes/NOD_node_declaration.hh
@@ -0,0 +1,135 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#pragma once
+
+#include <type_traits>
+
+#include "BLI_string_ref.hh"
+#include "BLI_vector.hh"
+
+#include "DNA_node_types.h"
+
+namespace blender::nodes {
+
+class NodeDeclarationBuilder;
+
+class SocketDeclaration {
+ protected:
+  std::string name_;
+  std::string identifier_;
+
+  friend NodeDeclarationBuilder;
+
+ public:
+  virtual bNodeSocket &build(bNodeTree &ntree, bNode &node, eNodeSocketInOut in_out) const = 0;
+  virtual bool matches(const bNodeSocket &socket) const = 0;
+  virtual bNodeSocket &update_or_build(bNodeTree &ntree, bNode &node, bNodeSocket &socket) const;
+
+  StringRefNull name() const;
+  StringRefNull identifier() const;
+};
+
+using SocketDeclarationPtr = std::unique_ptr<SocketDeclaration>;
+
+class NodeDeclaration {
+ private:
+  Vector<SocketDeclarationPtr> inputs_;
+  Vector<SocketDeclarationPtr> outputs_;
+
+  friend NodeDeclarationBuilder;
+
+ public:
+  void build(bNodeTree &ntree, bNode &node) const;
+  bool matches(const bNode &node) const;
+
+  Span<SocketDeclarationPtr> inputs() const;
+  Span<SocketDeclarationPtr> outputs() const;
+};
+
+class NodeDeclarationBuilder {
+ private:
+  NodeDeclaration &declaration_;
+
+ public:
+  NodeDeclarationBuilder(NodeDeclaration &declaration);
+
+  template<typename DeclType> DeclType &add_input(StringRef name, StringRef identifier = "");
+  template<typename DeclType> DeclType &add_output(StringRef name, StringRef identifier = "");
+};
+
+/* --------------------------------------------------------------------
+ * SocketDeclaration inline methods.
+ */
+
+inline StringRefNull SocketDeclaration::name() const
+{
+  return name_;
+}
+
+inline StringRefNull SocketDeclaration::identifier() const
+{
+  return identifier_;
+}
+
+/* --------------------------------------------------------------------
+ * NodeDeclarationBuilder inline methods.
+ */
+
+inline NodeDeclarationBuilder::NodeDeclarationBuilder(NodeDeclaration &declaration)
+    : declaration_(declaration)
+{
+}
+
+template<typename DeclType>
+inline DeclType &NodeDeclarationBuilder::add_input(StringRef name, StringRef identifier)
+{
+  static_assert(std::is_base_of_v<SocketDeclaration, DeclType>);
+  std::unique_ptr<DeclType> socket_decl = std::make_unique<DeclType>();
+  DeclType &ref = *socket_decl;
+  ref.name_ = name;
+  ref.identifier_ = identifier.is_empty() ? name : identifier;
+  declaration_.inputs_.append(std::move(socket_decl));
+  return ref;
+}
+
+template<typename DeclType>
+inline DeclType &NodeDeclarationBuilder::add_output(StringRef name, StringRef identifier)
+{
+  static_assert(std::is_base_of_v<SocketDeclaration, DeclType>);
+  std::unique_ptr<DeclType> socket_decl = std::make_unique<DeclType>();
+  DeclType &ref = *socket_decl;
+  ref.name_ = name;
+  ref.identifier_ = identifier.is_empty() ? name : identifier;
+  declaration_.outputs_.append(std::move(socket_decl));
+  return ref;
+}
+
+/* --------------------------------------------------------------------
+ * NodeDeclaration inline methods.
+ */
+
+inline Span<SocketDeclarationPtr> NodeDeclaration::inputs() const
+{
+  return inputs_;
+}
+
+inline Span<SocketDeclarationPtr> NodeDeclaration::outputs() const
+{
+  return outputs_;
+}
+
+}  // namespace blender::nodes
diff --git a/source/blender/nodes/NOD_socket.h b/source/blender/nodes/NOD_socket.h
index 6bcfda70d04..4f8e114c34a 100644
--- a/source/blender/nodes/NOD_socket.h
+++ b/source/blender/nodes/NOD_socket.h
@@ -43,7 +43,7 @@ struct bNodeSocket *node_add_socket_from_template(struct bNodeTree *ntree,
                                                   struct bNodeSocketTemplate *stemp,
                                                   eNodeSocketInOut in_out);
 
-void node_verify_socket_templates(struct bNodeTree *ntree, struct bNode *node);
+void node_verify_sockets(struct bNodeTree *ntree, struct bNode *node, bool do_id_user);
 
 void node_socket_init_default_value(struct bNodeSocket *sock);
 void node_socket_copy_default_value(struct bNodeSocket *to, const struct bNodeSocket *from);
diff --git a/source/blender/nodes/NOD_socket_declarations.hh b/source/blender/nodes/NOD_socket_declarations.hh
new file mode 100644
index 00000000000..639d2c12d73
--- /dev/null
+++ b/source/blender/nodes/NOD_socket_declarations.hh
@@ -0,0 +1,239 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#pragma once
+
+#include "NOD_node_declaration.hh"
+
+#include "RNA_types.h"
+
+#include "BLI_color.hh"
+#include "BLI_float3.hh"
+
+namespace blender::nodes::decl {
+
+class Float : public SocketDeclaration {
+ private:
+  float default_value_ = 0.0f;
+  float soft_min_value_ = -FLT_MAX;
+  float soft_max_value_ = FLT_MAX;
+  PropertySubType subtype_ = PROP_NONE;
+
+ public:
+  Float &min(const float value)
+  {
+    soft_min_value_ = value;
+    return *this;
+  }
+
+  Float &max(const float value)
+  {
+    soft_max_value_ = value;
+    return *this;
+  }
+
+  Float &default_value(const float value)
+  {
+    default_value_ = value;
+    return *this;
+  }
+
+  Float &subtype(PropertySubType subtype)
+  {
+    subtype_ = subtype;
+    return *this;
+  }
+
+  bNodeSocket &build(bNodeTree &ntree, bNode &node, eNodeSocketInOut in_out) const override;
+  bool matches(const bNodeSocket &socket) const override;
+  bNodeSocket &update_or_build(bNodeTree &ntree, bNode &node, bNodeSocket &socket) const override;
+};
+
+class Int : public SocketDeclaration {
+ private:
+  int default_value_ = 0;
+  int soft_min_value_ = INT32_MIN;
+  int soft_max_value_ = INT32_MAX;
+  PropertySubType subtype_ = PROP_NONE;
+
+ public:
+  Int &min(const int value)
+  {
+    soft_min_value_ = value;
+    return *this;
+  }
+
+  Int &max(const int value)
+  {
+    soft_max_value_ = value;
+    return *this;
+  }
+
+  Int &default_value(const int value)
+  {
+    default_value_ = value;
+    return *this;
+  }
+
+  Int &subtype(PropertySubType subtype)
+  {
+    subtype_ = subtype;
+    return *this;
+  }
+
+  bNodeSocket &build(bNodeTree &ntree, bNode &node, eNodeSocketInOut in_out) const override;
+  bool matches(const bNodeSocket &socket) const override;
+  bNodeSocket &update_or_build(bNodeTree &ntree, bNode &node, bNodeSocket &socket) const override;
+};
+
+class Vector : public SocketDeclaration {
+ private:
+  float3 default_value_ = {0, 0, 0};
+  PropertySubType subtype_ = PROP_NONE;
+
+ public:
+  Vector &default_value(const float3 value)
+  {
+    default_value_ = value;
+    return *this;
+  }
+
+  Vector &subtype(PropertySubType subtype)
+  {
+    subtype_ = subtype;
+    return *this;
+  }
+
+  bNodeSocket &build(bNodeTree &ntree, bNode &node, eNodeSocketInOut in_out) const override;
+  bool matches(const bNodeSocket &socket) const override;
+  bNodeSocket &update_or_build(bNodeTree &ntree, bNode &node, bNodeSocket &socket) const override;
+};
+
+class Bool : public SocketDeclaration {
+ private:
+  bool default_value_ = false;
+
+ public:
+  Bool &default_value(const bool value)
+  {
+    default_value_ = value;
+    return *this;
+  }
+
+  bNodeSocket &build(bNodeTree &ntree, bNode &node, eNodeSocketInOut in_out) const override;
+  bool matches(const bNodeSocket &socket) const override;
+};
+
+class Color : public SocketDeclaration {
+ private:
+  ColorGeometry4f default_value_;
+
+ public:
+  Color &default_value(const ColorGeometry4f value)
+  {
+    default_value_ = value;
+    return *this;
+  }
+
+  bNodeSocket &build(bNodeTree &ntree, bNode &node, eNodeSocketInOut in_out) const override;
+  bool matches(const bNodeSocket &socket) const override;
+};
+
+class String : public SocketDeclaration {
+ public:
+  bNodeSocket &build(bNodeTree &ntree, bNode &node, eNodeSocketInOut in_out) const override;
+  bool matches(const bNodeSocket &socket) const override;
+};
+
+namespace detail {
+struct CommonIDSocketData {
+  const char *idname;
+  bool hide_label = false;
+};
+
+bNodeSocket &build_id_socket(bNodeTree &ntree,
+                             bNode &node,
+                             eNodeSocketInOut in_out,
+                             const CommonIDSocketData &data,
+                             StringRefNull name,
+                             StringRefNull identifier);
+bool matches_id_socket(const bNodeSocket &socket,
+                       const CommonIDSocketData &data,
+                       StringRefNull name,
+                       StringRefNull identifier);
+
+template<typename Subtype> class IDSocketDeclaration : public SocketDeclaration {
+ private:
+  CommonIDSocketData data_;
+
+ public:
+  IDSocketDeclaration(const char *idname) : data_({idname})
+  {
+  }
+
+  Subtype &hide_label(bool value)
+  {
+    data_.hide_label = value;
+    return *(Subtype *)this;
+  }
+
+  bNodeSocket &build(bNodeTree &ntree, bNode &node, eNodeSocketInOut in_out) const override
+  {
+    return build_id_socket(ntree, node, in_out, data_, name_, identifier_);
+  }
+
+  bool matches(const bNodeSocket &socket) const override
+  {
+    return matches_id_socket(socket, data_, name_, identifier_);
+  }
+};
+}  // namespace detail
+
+class Object : public detail::IDSocketDeclaration<Object> {
+ public:
+  Object() : detail::IDSocketDeclaration<Object>("NodeSocketObject")
+  {
+  }
+};
+
+class Material : public detail::IDSocketDeclaration<Material> {
+ public:
+  Material() : detail::IDSocketDeclaration<Material>("NodeSocketMaterial")
+  {
+  }
+};
+
+class Collection : public detail::IDSocketDeclaration<Collection> {
+ public:
+  Collection() : detail::IDSocketDeclaration<Collection>("NodeSocketCollection")
+  {
+  }
+};
+
+class Texture : public detail::IDSocketDeclaration<Texture> {
+ public:
+  Texture() : detail::IDSocketDeclaration<Texture>("NodeSocketTexture")
+  {
+  }
+};
+
+class Geometry : public SocketDeclaration {
+ public:
+  bNodeSocket &build(bNodeTree &ntree, bNode &node, eNodeSocketInOut in_out) const override;
+  bool matches(const bNodeSocket &socket) const override;
+};
+
+}  // namespace blender::nodes::decl
diff --git a/source/blender/nodes/geometry/node_geometry_util.hh b/source/blender/nodes/geometry/node_geometry_util.hh
index 3251f9977bc..6a69c3d24ec 100644
--- a/source/blender/nodes/geometry/node_geometry_util.hh
+++ b/source/blender/nodes/geometry/node_geometry_util.hh
@@ -31,6 +31,7 @@
 
 #include "NOD_geometry.h"
 #include "NOD_geometry_exec.hh"
+#include "NOD_socket_declarations.hh"
 
 #include "node_util.h"
 
diff --git a/source/blender/nodes/geometry/nodes/node_geo_attribute_fill.cc b/source/blender/nodes/geometry/nodes/node_geo_attribute_fill.cc
index 389abe3b2aa..632e4f86572 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_attribute_fill.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_attribute_fill.cc
@@ -19,21 +19,19 @@
 
 #include "node_geometry_util.hh"
 
-static bNodeSocketTemplate geo_node_attribute_fill_in[] = {
-    {SOCK_GEOMETRY, N_("Geometry")},
-    {SOCK_STRING, N_("Attribute")},
-    {SOCK_VECTOR, N_("Value"), 0.0f, 0.0f, 0.0f, 0.0f, -FLT_MAX, FLT_MAX},
-    {SOCK_FLOAT, N_("Value"), 0.0f, 0.0f, 0.0f, 0.0f, -FLT_MAX, FLT_MAX},
-    {SOCK_RGBA, N_("Value"), 0.0f, 0.0f, 0.0f, 0.0f, -FLT_MAX, FLT_MAX},
-    {SOCK_BOOLEAN, N_("Value"), 0.0f, 0.0f, 0.0f, 0.0f, -FLT_MAX, FLT_MAX},
-    {SOCK_INT, N_("Value"), 0, 0, 0, 0, -10000000.0f, 10000000.0f},
-    {-1, ""},
-};
-
-static bNodeSocketTemplate geo_node_attribute_fill_out[] = {
-    {SOCK_GEOMETRY, N_("Geometry")},
-    {-1, ""},
-};
+namespace blender::nodes {
+
+static void geo_node_attribute_fill_declare(NodeDeclarationBuilder &b)
+{
+  b.add_input<decl::Geometry>("Geometry");
+  b.add_input<decl::String>("Attribute");
+  b.add_input<decl::Vector>("Value", "Value");
+  b.add_input<decl::Float>("Value", "Value_001");
+  b.add_input<decl::Color>("Value", "Value_002");
+  b.add_input<decl::Bool>("Value", "Value_003");
+  b.add_input<decl::Int>("Value", "Value_004");
+  b.add_output<decl::Geometry>("Geometry");
+}
 
 static void geo_node_attribute_fill_layout(uiLayout *layout, bContext *UNUSED(C), PointerRNA *ptr)
 {
@@ -66,8 +64,6 @@ static void geo_node_attribute_fill_update(bNodeTree *UNUSED(ntree), bNode *node
   nodeSetSocketAvailability(socket_value_int32, data_type == CD_PROP_INT32);
 }
 
-namespace blender::nodes {
-
 static AttributeDomain get_result_domain(const GeometryComponent &component, const StringRef name)
 {
   /* Use the domain of the result attribute if it already exists. */
@@ -157,10 +153,10 @@ void register_node_type_geo_attribute_fill()
   static bNodeType ntype;
 
   geo_node_type_base(&ntype, GEO_NODE_ATTRIBUTE_FILL, "Attribute Fill", NODE_CLASS_ATTRIBUTE, 0);
-  node_type_socket_templates(&ntype, geo_node_attribute_fill_in, geo_node_attribute_fill_out);
-  node_type_init(&ntype, geo_node_attribute_fill_init);
-  node_type_update(&ntype, geo_node_attribute_fill_update);
+  node_type_init(&ntype, blender::nodes::geo_node_attribute_fill_init);
+  node_type_update(&ntype, blender::nodes::geo_node_attribute_fill_update);
   ntype.geometry_node_execute = blender::nodes::geo_node_attribute_fill_exec;
-  ntype.draw_buttons = geo_node_attribute_fill_layout;
+  ntype.draw_buttons = blender::nodes::geo_node_attribute_fill_layout;
+  ntype.declare = blender::nodes::geo_node_attribute_fill_declare;
   nodeRegisterType(&ntype);
 }
diff --git a/source/blender/nodes/geometry/nodes/node_geo_curve_trim.cc b/source/blender/nodes/geometry/nodes/node_geo_curve_trim.cc
index f9415c6d27b..578f0298a19 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_curve_trim.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_curve_trim.cc
@@ -24,19 +24,17 @@
 
 using blender::attribute_math::mix2;
 
-static bNodeSocketTemplate geo_node_curve_trim_in[] = {
-    {SOCK_GEOMETRY, N_("Curve")},
-    {SOCK_FLOAT, N_("Start"), 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, PROP_FACTOR},
-    {SOCK_FLOAT, N_("End"), 1.0f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f, PROP_FACTOR},
-    {SOCK_FLOAT, N_("Start"), 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 10000.0f, PROP_DISTANCE},
-    {SOCK_FLOAT, N_("End"), 1.0f, 1.0f, 1.0f, 1.0f, 0.0f, 10000.0f, PROP_DISTANCE},
-    {-1, ""},
-};
+namespace blender::nodes {
 
-static bNodeSocketTemplate geo_node_curve_trim_out[] = {
-    {SOCK_GEOMETRY, N_("Curve")},
-    {-1, ""},
-};
+static void geo_node_curve_trim_declare(NodeDeclarationBuilder &b)
+{
+  b.add_input<decl::Geometry>("Curve");
+  b.add_input<decl::Float>("Start").min(0.0f).max(1.0f).subtype(PROP_FACTOR);
+  b.add_input<decl::Float>("End").min(0.0f).max(1.0f).subtype(PROP_FACTOR);
+  b.add_input<decl::Float>("Start", "Start_001").min(0.0f).subtype(PROP_DISTANCE);
+  b.add_input<decl::Float>("End", "End_001").min(0.0f).subtype(PROP_DISTANCE);
+  b.add_output<decl::Geometry>("Curve");
+}
 
 static void geo_node_curve_trim_layout(uiLayout *layout, bContext *UNUSED(C), PointerRNA *ptr)
 {
@@ -69,8 +67,6 @@ static void geo_node_curve_trim_update(bNodeTree *UNUSED(ntree), bNode *node)
   nodeSetSocketAvailability(end_len, mode == GEO_NODE_CURVE_INTERPOLATE_LENGTH);
 }
 
-namespace blender::nodes {
-
 struct TrimLocation {
   /* Control point index at the start side of the trim location. */
   int left_index;
@@ -399,12 +395,12 @@ void register_node_type_geo_curve_trim()
 {
   static bNodeType ntype;
   geo_node_type_base(&ntype, GEO_NODE_CURVE_TRIM, "Curve Trim", NODE_CLASS_GEOMETRY, 0);
-  node_type_socket_templates(&ntype, geo_node_curve_trim_in, geo_node_curve_trim_out);
   ntype.geometry_node_execute = blender::nodes::geo_node_curve_trim_exec;
-  ntype.draw_buttons = geo_node_curve_trim_layout;
+  ntype.draw_buttons = blender::nodes::geo_node_curve_trim_layout;
+  ntype.declare = blender::nodes::geo_node_curve_trim_declare;
   node_type_storage(
       &ntype, "NodeGeometryCurveTrim", node_free_standard_storage, node_copy_standard_storage);
-  node_type_init(&ntype, geo_node_curve_trim_init);
-  node_type_update(&ntype, geo_node_curve_trim_update);
+  node_type_init(&ntype, blender::nodes::geo_node_curve_trim_init);
+  node_type_update(&ntype, blender::nodes::geo_node_curve_trim_update);
   nodeRegisterType(&ntype);
 }
diff --git a/source/blender/nodes/geometry/nodes/node_geo_edge_split.cc b/source/blender/nodes/geometry/nodes/node_geo_edge_split.cc
index 740b828d503..867fecea251 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_edge_split.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_edge_split.cc
@@ -22,29 +22,21 @@ extern "C" {
 Mesh *doEdgeSplit(const Mesh *mesh, EdgeSplitModifierData *emd);
 }
 
-static bNodeSocketTemplate geo_node_edge_split_in[] = {
-    {SOCK_GEOMETRY, N_("Geometry")},
-    {SOCK_BOOLEAN, N_("Edge Angle"), true},
-    {SOCK_FLOAT,
-     N_("Angle"),
-     DEG2RADF(30.0f),
-     0.0f,
-     0.0f,
-     0.0f,
-     0.0f,
-     DEG2RADF(180.0f),
-     PROP_ANGLE},
-    {SOCK_BOOLEAN, N_("Sharp Edges")},
-    {-1, ""},
-};
-
-static bNodeSocketTemplate geo_node_edge_split_out[] = {
-    {SOCK_GEOMETRY, N_("Geometry")},
-    {-1, ""},
-};
-
 namespace blender::nodes {
 
+static void geo_node_edge_split_declare(NodeDeclarationBuilder &b)
+{
+  b.add_input<decl::Geometry>("Geometry");
+  b.add_input<decl::Bool>("Edge Angle").default_value(true);
+  b.add_input<decl::Float>("Angle")
+      .default_value(DEG2RADF(30.0f))
+      .min(0.0f)
+      .max(DEG2RADF(180.0f))
+      .subtype(PROP_ANGLE);
+  b.add_input<decl::Bool>("Sharp Edges");
+  b.add_output<decl::Geometry>("Geometry");
+}
+
 static void geo_node_edge_split_exec(GeoNodeExecParams params)
 {
   GeometrySet geometry_set = params.extract_input<GeometrySet>("Geometry");
@@ -91,7 +83,7 @@ void register_node_type_geo_edge_split()
   static bNodeType ntype;
 
   geo_node_type_base(&ntype, GEO_NODE_EDGE_SPLIT, "Edge Split", NODE_CLASS_GEOMETRY, 0);
-  node_type_socket_templates(&ntype, geo_node_edge_split_in, geo_node_edge_split_out);
   ntype.geometry_node_execute = blender::nodes::geo_node_edge_split_exec;
+  ntype.declare = blender::nodes::geo_node_edge_split_declare;
   nodeRegisterType(&ntype);
 }
diff --git a/source/blender/nodes/geometry/nodes/node_geo_input_material.cc b/source/blender/nodes/geometry/nodes/node_geo_input_material.cc
index 6bad71a62a2..8e805bd1359 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_input_material.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_input_material.cc
@@ -19,18 +19,18 @@
 
 #include "node_geometry_util.hh"
 
-static bNodeSocketTemplate geo_node_input_material_out[] = {
-    {SOCK_MATERIAL, N_("Material")},
-    {-1, ""},
-};
+namespace blender::nodes {
+
+static void geo_node_input_material_declare(NodeDeclarationBuilder &b)
+{
+  b.add_output<decl::Material>("Material");
+}
 
 static void geo_node_input_material_layout(uiLayout *layout, bContext *UNUSED(C), PointerRNA *ptr)
 {
   uiItemR(layout, ptr, "material", 0, "", ICON_NONE);
 }
 
-namespace blender::nodes {
-
 static void geo_node_input_material_exec(GeoNodeExecParams params)
 {
   Material *material = (Material *)params.node().id;
@@ -44,8 +44,8 @@ void register_node_type_geo_input_material()
   static bNodeType ntype;
 
   geo_node_type_base(&ntype, GEO_NODE_INPUT_MATERIAL, "Material", NODE_CLASS_INPUT, 0);
-  node_type_socket_templates(&ntype, nullptr, geo_node_input_material_out);
-  ntype.draw_buttons = geo_node_input_material_layout;
+  ntype.draw_buttons = blender::nodes::geo_node_input_material_layout;
+  ntype.declare = blender::nodes::geo_node_input_material_declare;
   ntype.geometry_node_execute = blender::nodes::geo_node_input_material_exec;
   nodeRegisterType(&ntype);
 }
diff --git a/source/blender/nodes/geometry/nodes/node_geo_is_viewport.cc b/source/blender/nodes/geometry/nodes/node_geo_is_viewport.cc
index ec875b9f983..f8a1c764f61 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_is_viewport.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_is_viewport.cc
@@ -18,13 +18,13 @@
 
 #include "node_geometry_util.hh"
 
-static bNodeSocketTemplate geo_node_is_viewport_out[] = {
-    {SOCK_BOOLEAN, N_("Is Viewport")},
-    {-1, ""},
-};
-
 namespace blender::nodes {
 
+static void geo_node_is_viewport_declare(NodeDeclarationBuilder &b)
+{
+  b.add_output<decl::Bool>("Is Viewport");
+}
+
 static void geo_node_is_viewport_exec(GeoNodeExecParams params)
 {
   const Depsgraph *depsgraph = params.depsgraph();
@@ -41,7 +41,7 @@ void register_node_type_geo_is_viewport()
   static bNodeType ntype;
 
   geo_node_type_base(&ntype, GEO_NODE_IS_VIEWPORT, "Is Viewport", NODE_CLASS_INPUT, 0);
-  node_type_socket_templates(&ntype, nullptr, geo_node_is_viewport_out);
   ntype.geometry_node_execute = blender::nodes::geo_node_is_viewport_exec;
+  ntype.declare = blender::nodes::geo_node_is_viewport_declare;
   nodeRegisterType(&ntype);
 }
diff --git a/source/blender/nodes/geometry/nodes/node_geo_mesh_primitive_circle.cc b/source/blender/nodes/geometry/nodes/node_geo_mesh_primitive_circle.cc
index b0bb547eb45..9c477c639a2 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_mesh_primitive_circle.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_mesh_primitive_circle.cc
@@ -25,16 +25,14 @@
 
 #include "node_geometry_util.hh"
 
-static bNodeSocketTemplate geo_node_mesh_primitive_circle_in[] = {
-    {SOCK_INT, N_("Vertices"), 32, 0.0f, 0.0f, 0.0f, 3, 4096},
-    {SOCK_FLOAT, N_("Radius"), 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, FLT_MAX, PROP_DISTANCE},
-    {-1, ""},
-};
+namespace blender::nodes {
 
-static bNodeSocketTemplate geo_node_mesh_primitive_circle_out[] = {
-    {SOCK_GEOMETRY, N_("Geometry")},
-    {-1, ""},
-};
+static void geo_node_mesh_primitive_circle_declare(NodeDeclarationBuilder &b)
+{
+  b.add_input<decl::Int>("Vertices").default_value(32).min(3);
+  b.add_input<decl::Float>("Radius").default_value(1.0f).min(0.0f).subtype(PROP_DISTANCE);
+  b.add_output<decl::Geometry>("Geometry");
+}
 
 static void geo_node_mesh_primitive_circle_layout(uiLayout *layout,
                                                   bContext *UNUSED(C),
@@ -55,8 +53,6 @@ static void geo_node_mesh_primitive_circle_init(bNodeTree *UNUSED(ntree), bNode
   node->storage = node_storage;
 }
 
-namespace blender::nodes {
-
 static int circle_vert_total(const GeometryNodeMeshCircleFillType fill_type, const int verts_num)
 {
   switch (fill_type) {
@@ -227,12 +223,11 @@ void register_node_type_geo_mesh_primitive_circle()
 
   geo_node_type_base(
       &ntype, GEO_NODE_MESH_PRIMITIVE_CIRCLE, "Mesh Circle", NODE_CLASS_GEOMETRY, 0);
-  node_type_socket_templates(
-      &ntype, geo_node_mesh_primitive_circle_in, geo_node_mesh_primitive_circle_out);
-  node_type_init(&ntype, geo_node_mesh_primitive_circle_init);
+  node_type_init(&ntype, blender::nodes::geo_node_mesh_primitive_circle_init);
   node_type_storage(
       &ntype, "NodeGeometryMeshCircle", node_free_standard_storage, node_copy_standard_storage);
   ntype.geometry_node_execute = blender::nodes::geo_node_mesh_primitive_circle_exec;
-  ntype.draw_buttons = geo_node_mesh_primitive_circle_layout;
+  ntype.draw_buttons = blender::nodes::geo_node_mesh_primitive_circle_layout;
+  ntype.declare = blender::nodes::geo_node_mesh_primitive_circle_declare;
   nodeRegisterType(&ntype);
 }
diff --git a/source/blender/nodes/geometry/nodes/node_geo_mesh_primitive_cone.cc b/source/blender/nodes/geometry/nodes/node_geo_mesh_primitive_cone.cc
index b834f5e2fa0..0d58476fc58 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_mesh_primitive_cone.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_mesh_primitive_cone.cc
@@ -25,18 +25,16 @@
 
 #include "node_geometry_util.hh"
 
-static bNodeSocketTemplate geo_node_mesh_primitive_cone_in[] = {
-    {SOCK_INT, N_("Vertices"), 32, 0.0f, 0.0f, 0.0f, 3, 4096},
-    {SOCK_FLOAT, N_("Radius Top"), 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, FLT_MAX, PROP_DISTANCE},
-    {SOCK_FLOAT, N_("Radius Bottom"), 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, FLT_MAX, PROP_DISTANCE},
-    {SOCK_FLOAT, N_("Depth"), 2.0f, 0.0f, 0.0f, 0.0f, 0.0f, FLT_MAX, PROP_DISTANCE},
-    {-1, ""},
-};
-
-static bNodeSocketTemplate geo_node_mesh_primitive_cone_out[] = {
-    {SOCK_GEOMETRY, N_("Geometry")},
-    {-1, ""},
-};
+namespace blender::nodes {
+
+static void geo_node_mesh_primitive_cone_declare(NodeDeclarationBuilder &b)
+{
+  b.add_input<decl::Int>("Vertices").default_value(32).min(3);
+  b.add_input<decl::Float>("Radius Top").min(0.0f).subtype(PROP_DISTANCE);
+  b.add_input<decl::Float>("Radius Bottom").default_value(1.0f).min(0.0f).subtype(PROP_DISTANCE);
+  b.add_input<decl::Float>("Depth").default_value(2.0f).min(0.0f).subtype(PROP_DISTANCE);
+  b.add_output<decl::Geometry>("Geometry");
+}
 
 static void geo_node_mesh_primitive_cone_layout(uiLayout *layout,
                                                 bContext *UNUSED(C),
@@ -57,8 +55,6 @@ static void geo_node_mesh_primitive_cone_init(bNodeTree *UNUSED(ntree), bNode *n
   node->storage = node_storage;
 }
 
-namespace blender::nodes {
-
 static int vert_total(const GeometryNodeMeshCircleFillType fill_type,
                       const int verts_num,
                       const bool top_is_point,
@@ -575,12 +571,11 @@ void register_node_type_geo_mesh_primitive_cone()
   static bNodeType ntype;
 
   geo_node_type_base(&ntype, GEO_NODE_MESH_PRIMITIVE_CONE, "Cone", NODE_CLASS_GEOMETRY, 0);
-  node_type_socket_templates(
-      &ntype, geo_node_mesh_primitive_cone_in, geo_node_mesh_primitive_cone_out);
-  node_type_init(&ntype, geo_node_mesh_primitive_cone_init);
+  node_type_init(&ntype, blender::nodes::geo_node_mesh_primitive_cone_init);
   node_type_storage(
       &ntype, "NodeGeometryMeshCone", node_free_standard_storage, node_copy_standard_storage);
   ntype.geometry_node_execute = blender::nodes::geo_node_mesh_primitive_cone_exec;
-  ntype.draw_buttons = geo_node_mesh_primitive_cone_layout;
+  ntype.draw_buttons = blender::nodes::geo_node_mesh_primitive_cone_layout;
+  ntype.declare = blender::nodes::geo_node_mesh_primitive_cone_declare;
   nodeRegisterType(&ntype);
 }
diff --git a/source/blender/nodes/geometry/nodes/node_geo_object_info.cc b/source/blender/nodes/geometry/nodes/node_geo_object_info.cc
index 167812d5656..ab99c9bb3f8 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_object_info.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_object_info.cc
@@ -21,25 +21,22 @@
 
 #include "node_geometry_util.hh"
 
-static bNodeSocketTemplate geo_node_object_info_in[] = {
-    {SOCK_OBJECT, N_("Object"), 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, PROP_NONE, SOCK_HIDE_LABEL},
-    {-1, ""},
-};
-
-static bNodeSocketTemplate geo_node_object_info_out[] = {
-    {SOCK_VECTOR, N_("Location")},
-    {SOCK_VECTOR, N_("Rotation")},
-    {SOCK_VECTOR, N_("Scale")},
-    {SOCK_GEOMETRY, N_("Geometry")},
-    {-1, ""},
-};
+namespace blender::nodes {
+
+static void geo_node_object_info_declare(NodeDeclarationBuilder &b)
+{
+  b.add_input<decl::Object>("Object").hide_label(true);
+  b.add_output<decl::Vector>("Location");
+  b.add_output<decl::Vector>("Rotation");
+  b.add_output<decl::Vector>("Scale");
+  b.add_output<decl::Geometry>("Geometry");
+}
 
 static void geo_node_object_info_layout(uiLayout *layout, bContext *UNUSED(C), PointerRNA *ptr)
 {
   uiItemR(layout, ptr, "transform_space", UI_ITEM_R_EXPAND, nullptr, ICON_NONE);
 }
 
-namespace blender::nodes {
 static void geo_node_object_info_exec(GeoNodeExecParams params)
 {
   const bNode &bnode = params.node();
@@ -105,11 +102,11 @@ void register_node_type_geo_object_info()
   static bNodeType ntype;
 
   geo_node_type_base(&ntype, GEO_NODE_OBJECT_INFO, "Object Info", NODE_CLASS_INPUT, 0);
-  node_type_socket_templates(&ntype, geo_node_object_info_in, geo_node_object_info_out);
   node_type_init(&ntype, blender::nodes::geo_node_object_info_node_init);
   node_type_storage(
       &ntype, "NodeGeometryObjectInfo", node_free_standard_storage, node_copy_standard_storage);
   ntype.geometry_node_execute = blender::nodes::geo_node_object_info_exec;
-  ntype.draw_buttons = geo_node_object_info_layout;
+  ntype.draw_buttons = blender::nodes::geo_node_object_info_layout;
+  ntype.declare = blender::nodes::geo_node_object_info_declare;
   nodeRegisterType(&ntype);
 }
diff --git a/source/blender/nodes/geometry/nodes/node_geo_transform.cc b/source/blender/nodes/geometry/nodes/node_geo_transform.cc
index 1ad5dbea492..d7423aa6d32 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_transform.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_transform.cc
@@ -32,21 +32,17 @@
 
 #include "node_geometry_util.hh"
 
-static bNodeSocketTemplate geo_node_transform_in[] = {
-    {SOCK_GEOMETRY, N_("Geometry")},
-    {SOCK_VECTOR, N_("Translation"), 0.0f, 0.0f, 0.0f, 1.0f, -FLT_MAX, FLT_MAX, PROP_TRANSLATION},
-    {SOCK_VECTOR, N_("Rotation"), 0.0f, 0.0f, 0.0f, 1.0f, -FLT_MAX, FLT_MAX, PROP_EULER},
-    {SOCK_VECTOR, N_("Scale"), 1.0f, 1.0f, 1.0f, 1.0f, -FLT_MAX, FLT_MAX, PROP_XYZ},
-    {-1, ""},
-};
-
-static bNodeSocketTemplate geo_node_transform_out[] = {
-    {SOCK_GEOMETRY, N_("Geometry")},
-    {-1, ""},
-};
-
 namespace blender::nodes {
 
+static void geo_node_transform_declare(NodeDeclarationBuilder &b)
+{
+  b.add_input<decl::Geometry>("Geometry");
+  b.add_input<decl::Vector>("Translation").subtype(PROP_TRANSLATION);
+  b.add_input<decl::Vector>("Rotation").subtype(PROP_EULER);
+  b.add_input<decl::Vector>("Scale").default_value({1, 1, 1}).subtype(PROP_XYZ);
+  b.add_output<decl::Geometry>("Geometry");
+}
+
 static bool use_translate(const float3 rotation, const float3 scale)
 {
   if (compare_ff(rotation.length_squared(), 0.0f, 1e-9f) != 1) {
@@ -206,7 +202,7 @@ void register_node_type_geo_transform()
   static bNodeType ntype;
 
   geo_node_type_base(&ntype, GEO_NODE_TRANSFORM, "Transform", NODE_CLASS_GEOMETRY, 0);
-  node_type_socket_templates(&ntype, geo_node_transform_in, geo_node_transform_out);
+  ntype.declare = blender::nodes::geo_node_transform_declare;
   ntype.geometry_node_execute = blender::nodes::geo_node_transform_exec;
   nodeRegisterType(&ntype);
 }
diff --git a/source/blender/nodes/intern/node_declaration.cc b/source/blender/nodes/intern/node_declaration.cc
new file mode 100644
index 00000000000..dff92d5884f
--- /dev/null
+++ b/source/blender/nodes/intern/node_declaration.cc
@@ -0,0 +1,65 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include "NOD_node_declaration.hh"
+
+namespace blender::nodes {
+
+void NodeDeclaration::build(bNodeTree &ntree, bNode &node) const
+{
+  for (const SocketDeclarationPtr &decl : inputs_) {
+    decl->build(ntree, node, SOCK_IN);
+  }
+  for (const SocketDeclarationPtr &decl : outputs_) {
+    decl->build(ntree, node, SOCK_OUT);
+  }
+}
+
+bool NodeDeclaration::matches(const bNode &node) const
+{
+  auto check_sockets = [&](ListBase sockets, Span<SocketDeclarationPtr> socket_decls) {
+    const int tot_sockets = BLI_listbase_count(&sockets);
+    if (tot_sockets != socket_decls.size()) {
+      return false;
+    }
+    int i;
+    LISTBASE_FOREACH_INDEX (const bNodeSocket *, socket, &sockets, i) {
+      const SocketDeclaration &socket_decl = *socket_decls[i];
+      if (!socket_decl.matches(*socket)) {
+        return false;
+      }
+    }
+    return true;
+  };
+
+  if (!check_sockets(node.inputs, inputs_)) {
+    return false;
+  }
+  if (!check_sockets(node.outputs, outputs_)) {
+    return false;
+  }
+  return true;
+}
+
+bNodeSocket &SocketDeclaration::update_or_build(bNodeTree &ntree,
+                                                bNode &node,
+                                                bNodeSocket &socket) const
+{
+  /* By default just rebuild. */
+  return this->build(ntree, node, (eNodeSocketInOut)socket.in_out);
+}
+
+}  // namespace blender::nodes
diff --git a/source/blender/nodes/intern/node_socket.cc b/source/blender/nodes/intern/node_socket.cc
index 528616eb23a..d386781e3ce 100644
--- a/source/blender/nodes/intern/node_socket.cc
+++ b/source/blender/nodes/intern/node_socket.cc
@@ -44,10 +44,14 @@
 
 #include "MEM_guardedalloc.h"
 
+#include "NOD_node_declaration.hh"
 #include "NOD_socket.h"
 
 #include "FN_cpp_type_make.hh"
 
+using namespace blender;
+using blender::nodes::SocketDeclarationPtr;
+
 struct bNodeSocket *node_add_socket_from_template(struct bNodeTree *ntree,
                                                   struct bNode *node,
                                                   struct bNodeSocketTemplate *stemp,
@@ -182,9 +186,96 @@ static void verify_socket_template_list(bNodeTree *ntree,
   }
 }
 
-void node_verify_socket_templates(bNodeTree *ntree, bNode *node)
+static void refresh_socket_list(bNodeTree &ntree,
+                                bNode &node,
+                                ListBase &sockets,
+                                Span<SocketDeclarationPtr> socket_decls,
+                                const eNodeSocketInOut in_out,
+                                const bool do_id_user)
+{
+  Vector<bNodeSocket *> old_sockets = sockets;
+  VectorSet<bNodeSocket *> new_sockets;
+  for (const SocketDeclarationPtr &socket_decl : socket_decls) {
+    /* Try to find a socket that corresponds to the declaration. */
+    bNodeSocket *old_socket_with_same_identifier = nullptr;
+    for (const int i : old_sockets.index_range()) {
+      bNodeSocket &old_socket = *old_sockets[i];
+      if (old_socket.identifier == socket_decl->identifier()) {
+        old_sockets.remove_and_reorder(i);
+        old_socket_with_same_identifier = &old_socket;
+        break;
+      }
+    }
+    bNodeSocket *new_socket = nullptr;
+    if (old_socket_with_same_identifier == nullptr) {
+      /* Create a completely new socket. */
+      new_socket = &socket_decl->build(ntree, node, in_out);
+    }
+    else {
+      STRNCPY(old_socket_with_same_identifier->name, socket_decl->name().c_str());
+      if (socket_decl->matches(*old_socket_with_same_identifier)) {
+        /* The existing socket matches exactly, just use it. */
+        new_socket = old_socket_with_same_identifier;
+      }
+      else {
+        /* Clear out identifier to avoid name collisions when a new socket is created. */
+        old_socket_with_same_identifier->identifier[0] = '\0';
+        new_socket = &socket_decl->update_or_build(ntree, node, *old_socket_with_same_identifier);
+
+        if (new_socket == old_socket_with_same_identifier) {
+          /* The existing socket has been updated, set the correct identifier again. */
+          STRNCPY(new_socket->identifier, socket_decl->identifier().c_str());
+        }
+        else {
+          /* Move links to new socket with same identifier. */
+          LISTBASE_FOREACH (bNodeLink *, link, &ntree.links) {
+            if (link->fromsock == old_socket_with_same_identifier) {
+              link->fromsock = new_socket;
+            }
+            else if (link->tosock == old_socket_with_same_identifier) {
+              link->tosock = new_socket;
+            }
+          }
+        }
+      }
+    }
+    new_sockets.add_new(new_socket);
+  }
+  LISTBASE_FOREACH_MUTABLE (bNodeSocket *, old_socket, &sockets) {
+    if (!new_sockets.contains(old_socket)) {
+      nodeRemoveSocketEx(&ntree, &node, old_socket, do_id_user);
+    }
+  }
+  BLI_listbase_clear(&sockets);
+  for (bNodeSocket *socket : new_sockets) {
+    BLI_addtail(&sockets, socket);
+  }
+}
+
+static void refresh_node(bNodeTree &ntree,
+                         bNode &node,
+                         blender::nodes::NodeDeclaration &node_decl,
+                         bool do_id_user)
+{
+  refresh_socket_list(ntree, node, node.inputs, node_decl.inputs(), SOCK_IN, do_id_user);
+  refresh_socket_list(ntree, node, node.outputs, node_decl.outputs(), SOCK_OUT, do_id_user);
+}
+
+void node_verify_sockets(bNodeTree *ntree, bNode *node, bool do_id_user)
 {
   bNodeType *ntype = node->typeinfo;
+  if (ntype == nullptr) {
+    return;
+  }
+  if (ntype->declare != nullptr) {
+    blender::nodes::NodeDeclaration node_decl;
+    blender::nodes::NodeDeclarationBuilder builder{node_decl};
+    ntype->declare(builder);
+    if (!node_decl.matches(*node)) {
+      refresh_node(*ntree, *node, node_decl, do_id_user);
+    }
+    return;
+  }
   /* Don't try to match socket lists when there are no templates.
    * This prevents dynamically generated sockets to be removed, like for
    * group, image or render layer nodes. We have an explicit check for the
diff --git a/source/blender/nodes/intern/node_socket_declarations.cc b/source/blender/nodes/intern/node_socket_declarations.cc
new file mode 100644
index 00000000000..418fed146fb
--- /dev/null
+++ b/source/blender/nodes/intern/node_socket_declarations.cc
@@ -0,0 +1,330 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include "NOD_socket_declarations.hh"
+
+#include "BKE_node.h"
+
+#include "BLI_math_vector.h"
+
+namespace blender::nodes::decl {
+
+static void modify_subtype_except_for_storage(bNodeSocket &socket, int new_subtype)
+{
+  const char *idname = nodeStaticSocketType(socket.type, new_subtype);
+  BLI_strncpy(socket.idname, idname, sizeof(socket.idname));
+  bNodeSocketType *socktype = nodeSocketTypeFind(idname);
+  socket.typeinfo = socktype;
+}
+
+/* --------------------------------------------------------------------
+ * Float.
+ */
+
+bNodeSocket &Float::build(bNodeTree &ntree, bNode &node, eNodeSocketInOut in_out) const
+{
+  bNodeSocket &socket = *nodeAddStaticSocket(
+      &ntree, &node, in_out, SOCK_FLOAT, subtype_, identifier_.c_str(), name_.c_str());
+  bNodeSocketValueFloat &value = *(bNodeSocketValueFloat *)socket.default_value;
+  value.min = soft_min_value_;
+  value.max = soft_max_value_;
+  value.value = default_value_;
+  return socket;
+}
+
+bool Float::matches(const bNodeSocket &socket) const
+{
+  if (socket.type != SOCK_FLOAT) {
+    return false;
+  }
+  if (socket.typeinfo->subtype != subtype_) {
+    return false;
+  }
+  if (socket.name != name_) {
+    return false;
+  }
+  if (socket.identifier != identifier_) {
+    return false;
+  }
+  bNodeSocketValueFloat &value = *(bNodeSocketValueFloat *)socket.default_value;
+  if (value.min != soft_min_value_) {
+    return false;
+  }
+  if (value.max != soft_max_value_) {
+    return false;
+  }
+  return true;
+}
+
+bNodeSocket &Float::update_or_build(bNodeTree &ntree, bNode &node, bNodeSocket &socket) const
+{
+  if (socket.type != SOCK_FLOAT) {
+    return this->build(ntree, node, (eNodeSocketInOut)socket.in_out);
+  }
+  if (socket.typeinfo->subtype != subtype_) {
+    modify_subtype_except_for_storage(socket, subtype_);
+  }
+  bNodeSocketValueFloat &value = *(bNodeSocketValueFloat *)socket.default_value;
+  value.min = soft_min_value_;
+  value.max = soft_max_value_;
+  value.subtype = subtype_;
+  return socket;
+}
+
+/* --------------------------------------------------------------------
+ * Int.
+ */
+
+bNodeSocket &Int::build(bNodeTree &ntree, bNode &node, eNodeSocketInOut in_out) const
+{
+  bNodeSocket &socket = *nodeAddStaticSocket(
+      &ntree, &node, in_out, SOCK_INT, subtype_, identifier_.c_str(), name_.c_str());
+  bNodeSocketValueInt &value = *(bNodeSocketValueInt *)socket.default_value;
+  value.min = soft_min_value_;
+  value.max = soft_max_value_;
+  value.value = default_value_;
+  return socket;
+}
+
+bool Int::matches(const bNodeSocket &socket) const
+{
+  if (socket.type != SOCK_INT) {
+    return false;
+  }
+  if (socket.typeinfo->subtype != subtype_) {
+    return false;
+  }
+  if (socket.name != name_) {
+    return false;
+  }
+  if (socket.identifier != identifier_) {
+    return false;
+  }
+  bNodeSocketValueInt &value = *(bNodeSocketValueInt *)socket.default_value;
+  if (value.min != soft_min_value_) {
+    return false;
+  }
+  if (value.max != soft_max_value_) {
+    return false;
+  }
+  return true;
+}
+
+bNodeSocket &Int::update_or_build(bNodeTree &ntree, bNode &node, bNodeSocket &socket) const
+{
+  if (socket.type != SOCK_INT) {
+    return this->build(ntree, node, (eNodeSocketInOut)socket.in_out);
+  }
+  if (socket.typeinfo->subtype != subtype_) {
+    modify_subtype_except_for_storage(socket, subtype_);
+  }
+  bNodeSocketValueInt &value = *(bNodeSocketValueInt *)socket.default_value;
+  value.min = soft_min_value_;
+  value.max = soft_max_value_;
+  value.subtype = subtype_;
+  return socket;
+}
+
+/* --------------------------------------------------------------------
+ * Vector.
+ */
+
+bNodeSocket &Vector::build(bNodeTree &ntree, bNode &node, eNodeSocketInOut in_out) const
+{
+  bNodeSocket &socket = *nodeAddStaticSocket(
+      &ntree, &node, in_out, SOCK_VECTOR, subtype_, identifier_.c_str(), name_.c_str());
+  bNodeSocketValueVector &value = *(bNodeSocketValueVector *)socket.default_value;
+  copy_v3_v3(value.value, default_value_);
+  return socket;
+}
+
+bool Vector::matches(const bNodeSocket &socket) const
+{
+  if (socket.type != SOCK_VECTOR) {
+    return false;
+  }
+  if (socket.typeinfo->subtype != subtype_) {
+    return false;
+  }
+  if (socket.name != name_) {
+    return false;
+  }
+  if (socket.identifier != identifier_) {
+    return false;
+  }
+  return true;
+}
+
+bNodeSocket &Vector::update_or_build(bNodeTree &ntree, bNode &node, bNodeSocket &socket) const
+{
+  if (socket.type != SOCK_VECTOR) {
+    return this->build(ntree, node, (eNodeSocketInOut)socket.in_out);
+  }
+  if (socket.typeinfo->subtype != subtype_) {
+    modify_subtype_except_for_storage(socket, subtype_);
+  }
+  bNodeSocketValueVector &value = *(bNodeSocketValueVector *)socket.default_value;
+  value.subtype = subtype_;
+  STRNCPY(socket.name, name_.c_str());
+  return socket;
+}
+
+/* --------------------------------------------------------------------
+ * Bool.
+ */
+
+bNodeSocket &Bool::build(bNodeTree &ntree, bNode &node, eNodeSocketInOut in_out) const
+{
+  bNodeSocket &socket = *nodeAddStaticSocket(
+      &ntree, &node, in_out, SOCK_BOOLEAN, PROP_NONE, identifier_.c_str(), name_.c_str());
+  bNodeSocketValueBoolean &value = *(bNodeSocketValueBoolean *)socket.default_value;
+  value.value = default_value_;
+  return socket;
+}
+
+bool Bool::matches(const bNodeSocket &socket) const
+{
+  if (socket.type != SOCK_BOOLEAN) {
+    return false;
+  }
+  if (socket.name != name_) {
+    return false;
+  }
+  if (socket.identifier != identifier_) {
+    return false;
+  }
+  return true;
+}
+
+/* --------------------------------------------------------------------
+ * Color.
+ */
+
+bNodeSocket &Color::build(bNodeTree &ntree, bNode &node, eNodeSocketInOut in_out) const
+{
+  bNodeSocket &socket = *nodeAddStaticSocket(
+      &ntree, &node, in_out, SOCK_RGBA, PROP_NONE, identifier_.c_str(), name_.c_str());
+  bNodeSocketValueRGBA &value = *(bNodeSocketValueRGBA *)socket.default_value;
+  copy_v4_v4(value.value, default_value_);
+  return socket;
+}
+
+bool Color::matches(const bNodeSocket &socket) const
+{
+  if (socket.type != SOCK_RGBA) {
+    return false;
+  }
+  if (socket.name != name_) {
+    return false;
+  }
+  if (socket.identifier != identifier_) {
+    return false;
+  }
+  return true;
+}
+
+/* --------------------------------------------------------------------
+ * String.
+ */
+
+bNodeSocket &String::build(bNodeTree &ntree, bNode &node, eNodeSocketInOut in_out) const
+{
+  bNodeSocket &socket = *nodeAddStaticSocket(
+      &ntree, &node, in_out, SOCK_STRING, PROP_NONE, identifier_.c_str(), name_.c_str());
+  return socket;
+}
+
+bool String::matches(const bNodeSocket &socket) const
+{
+  if (socket.type != SOCK_STRING) {
+    return false;
+  }
+  if (socket.name != name_) {
+    return false;
+  }
+  if (socket.identifier != identifier_) {
+    return false;
+  }
+  return true;
+}
+
+/* --------------------------------------------------------------------
+ * IDSocketDeclaration.
+ */
+
+namespace detail {
+bNodeSocket &build_id_socket(bNodeTree &ntree,
+                             bNode &node,
+                             eNodeSocketInOut in_out,
+                             const CommonIDSocketData &data,
+                             StringRefNull name,
+                             StringRefNull identifier)
+{
+  bNodeSocket &socket = *nodeAddSocket(
+      &ntree, &node, in_out, data.idname, name.c_str(), identifier.c_str());
+  if (data.hide_label) {
+    socket.flag |= SOCK_HIDE_LABEL;
+  }
+  return socket;
+}
+
+bool matches_id_socket(const bNodeSocket &socket,
+                       const CommonIDSocketData &data,
+                       StringRefNull name,
+                       StringRefNull identifier)
+{
+  if (!STREQ(socket.idname, data.idname)) {
+    return false;
+  }
+  if (data.hide_label != ((socket.flag & SOCK_HIDE_LABEL) != 0)) {
+    return false;
+  }
+  if (socket.name != name) {
+    return false;
+  }
+  if (socket.identifier != identifier) {
+    return false;
+  }
+  return true;
+}
+}  // namespace detail
+
+/* --------------------------------------------------------------------
+ * Geometry.
+ */
+
+bNodeSocket &Geometry::build(bNodeTree &ntree, bNode &node, eNodeSocketInOut in_out) const
+{
+  bNodeSocket &socket = *nodeAddSocket(
+      &ntree, &node, in_out, "NodeSocketGeometry", identifier_.c_str(), name_.c_str());
+  return socket;
+}
+
+bool Geometry::matches(const bNodeSocket &socket) const
+{
+  if (socket.type != SOCK_GEOMETRY) {
+    return false;
+  }
+  if (socket.name != name_) {
+    return false;
+  }
+  if (socket.identifier != identifier_) {
+    return false;
+  }
+  return true;
+}
+
+}  // namespace blender::nodes::decl