Fix T94827: Group Input/Output cannot connect to custom sockets

Caused by rBa5c59fb90ef9.

Since Group Input and Output sockets happen to be of type `SOCK_CUSTOM`
[and since rBa5c59fb90ef9 custom py defined sockets are too :)] a check
introduced in rB513066e8ad6f that prevents connections for `SOCK_CUSTOM`
triggered.

Now refine the check, so it specifically looks for NODE_GROUP_INPUT /
NODE_GROUP_OUTPUT, too (this keeps the intention intact to not connect
group inputs to group outputs and vice versa, but allows custom py
defined sockets to connect again) and put it in new utility function.

Maniphest Tasks: T94827

Differential Revision: https://developer.blender.org/D13817

1 files changed, 7 insertions, 2 deletions

diff --git a/source/blender/nodes/intern/node_common.cc b/source/blender/nodes/intern/node_common.cc
index e5ec50858d9..4fcc96470c5 100644
--- a/source/blender/nodes/intern/node_common.cc
+++ b/source/blender/nodes/intern/node_common.cc
@@ -442,6 +442,11 @@ void BKE_node_tree_unlink_id(ID *id, struct bNodeTree *ntree)
 /** \name Node #GROUP_INPUT / #GROUP_OUTPUT
  * \{ */
 
+static bool is_group_extension_socket(const bNode *node, const bNodeSocket *socket)
+{
+  return socket->type == SOCK_CUSTOM && ELEM(node->type, NODE_GROUP_OUTPUT, NODE_GROUP_INPUT);
+}
+
 static void node_group_input_init(bNodeTree *ntree, bNode *node)
 {
   node_group_input_update(ntree, node);
@@ -493,7 +498,7 @@ void node_group_input_update(bNodeTree *ntree, bNode *node)
      * This could be improved by choosing the "best" type among all links,
      * whatever that means.
      */
-    if (link->tosock->type != SOCK_CUSTOM) {
+    if (!is_group_extension_socket(link->tonode, link->tosock)) {
       exposelink = link;
       break;
     }
@@ -590,7 +595,7 @@ void node_group_output_update(bNodeTree *ntree, bNode *node)
      * This could be improved by choosing the "best" type among all links,
      * whatever that means.
      */
-    if (link->fromsock->type != SOCK_CUSTOM) {
+    if (!is_group_extension_socket(link->fromnode, link->fromsock)) {
       exposelink = link;
       break;
     }