From a57709ca253bb7a20fa24f2ab3e1b2486601de1d Mon Sep 17 00:00:00 2001
From: Jacques Lucke <jacques@blender.org>
Date: Thu, 24 Jul 2025 08:13:34 +0200
Subject: [PATCH] Fix #142828: broken socket usage inference for some nodes

The issue was an oversight in f7f18cd0c74871671e32229c291c9176e9d68f7f.

This patch also adds some unit tests that would have caught this error.

Pull Request: https://projects.blender.org/blender/blender/pulls/143026
---
 .../nodes/intern/socket_usage_inference.cc    |  3 +-
 .../node_group/socket_usage_inference.blend   |  3 +
 tests/python/CMakeLists.txt                   |  7 ++
 .../python/bl_node_socket_usage_inference.py  | 84 +++++++++++++++++++
 4 files changed, 96 insertions(+), 1 deletion(-)
 create mode 100644 tests/files/node_group/socket_usage_inference.blend
 create mode 100644 tests/python/bl_node_socket_usage_inference.py

diff --git a/source/blender/nodes/intern/socket_usage_inference.cc b/source/blender/nodes/intern/socket_usage_inference.cc
index 90696a26329..3f69feb8013 100644
--- a/source/blender/nodes/intern/socket_usage_inference.cc
+++ b/source/blender/nodes/intern/socket_usage_inference.cc
@@ -438,7 +438,8 @@ struct SocketUsageInferencer {
       return;
     }
     if (!socket_decl->usage_inference_fn) {
-      all_socket_usages_.add_new(socket, true);
+      this->usage_task__with_dependent_sockets(
+          socket, socket->owner_node().output_sockets(), {}, socket.context);
       return;
     }
     InputSocketUsageParams params{
diff --git a/tests/files/node_group/socket_usage_inference.blend b/tests/files/node_group/socket_usage_inference.blend
new file mode 100644
index 00000000000..9a91d5e35df
--- /dev/null
+++ b/tests/files/node_group/socket_usage_inference.blend
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:283e81209fb5aa84e41871c3237d4e8669d3e0ec8a71aafb39cc24324bb995be
+size 540679
diff --git a/tests/python/CMakeLists.txt b/tests/python/CMakeLists.txt
index 0139dac2195..b0d7a51b470 100644
--- a/tests/python/CMakeLists.txt
+++ b/tests/python/CMakeLists.txt
@@ -606,6 +606,13 @@ if(TEST_SRC_DIR_EXISTS)
     --testdir "${TEST_SRC_DIR}/node_group"
   )
 
+  add_blender_test(
+    bl_node_socket_usage_inference
+    --python ${CMAKE_CURRENT_LIST_DIR}/bl_node_socket_usage_inference.py
+    --
+    --testdir "${TEST_SRC_DIR}/node_group"
+  )
+
   add_blender_test(
     bl_node_group_compat
     --python ${CMAKE_CURRENT_LIST_DIR}/bl_node_group_compat.py
diff --git a/tests/python/bl_node_socket_usage_inference.py b/tests/python/bl_node_socket_usage_inference.py
new file mode 100644
index 00000000000..1b55ffdaa05
--- /dev/null
+++ b/tests/python/bl_node_socket_usage_inference.py
@@ -0,0 +1,84 @@
+# SPDX-FileCopyrightText: 2025 Blender Authors
+#
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+import pathlib
+import sys
+import tempfile
+import bpy
+import unittest
+
+args = None
+
+
+class StructureTypeInferenceTest(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        cls.testdir = args.testdir
+
+    def setUp(self):
+        self.assertTrue(self.testdir.exists(),
+                        "Test dir {0} should exist".format(self.testdir))
+
+    def load_testfile(self):
+        bpy.ops.wm.open_mainfile(filepath=str(self.testdir / "socket_usage_inference.blend"))
+
+    def assertUsed(self, socket):
+        self.assertTrue(socket.is_icon_visible)
+        self.assertFalse(socket.is_inactive)
+
+    def assertGrayedOut(self, socket):
+        self.assertTrue(socket.is_icon_visible)
+        self.assertTrue(socket.is_inactive)
+
+    def assertHidden(self, socket):
+        self.assertFalse(socket.is_icon_visible)
+
+    def test_geometry_nodes(self):
+        self.load_testfile()
+        tree = bpy.data.node_groups["Geometry Nodes"]
+
+        node = tree.nodes["Math Group"]
+        self.assertUsed(node.inputs["A"])
+        self.assertUsed(node.inputs["B"])
+
+        node = tree.nodes["Menu Switch Group"]
+        self.assertUsed(node.inputs["Menu"])
+        self.assertUsed(node.inputs["A"])
+        self.assertHidden(node.inputs["B"])
+
+        node = tree.nodes["Transform Matrix"]
+        self.assertUsed(node.inputs["Mode"])
+        self.assertUsed(node.inputs["Geometry"])
+        self.assertUsed(node.inputs["Transform"])
+        self.assertHidden(node.inputs["Translation"])
+        self.assertHidden(node.inputs["Rotation"])
+        self.assertHidden(node.inputs["Scale"])
+
+        node = tree.nodes["Transform Components"]
+        self.assertUsed(node.inputs["Mode"])
+        self.assertUsed(node.inputs["Geometry"])
+        self.assertUsed(node.inputs["Translation"])
+        self.assertUsed(node.inputs["Rotation"])
+        self.assertUsed(node.inputs["Scale"])
+        self.assertHidden(node.inputs["Transform"])
+
+
+def main():
+    global args
+    import argparse
+
+    if '--' in sys.argv:
+        argv = [sys.argv[0]] + sys.argv[sys.argv.index('--') + 1:]
+    else:
+        argv = sys.argv
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--testdir', required=True, type=pathlib.Path)
+    args, remaining = parser.parse_known_args(argv)
+
+    unittest.main(argv=remaining)
+
+
+if __name__ == "__main__":
+    main()