[Bf-blender-cvs] [7c860ab9d4b] blender-v3.0-release: Fix T92499: duplicating geometry nodes modifier causes crash

[Jacques Lucke]

Commit: 7c860ab9d4b54f9c394d3c2769927f55c6737b5f
Author: Jacques Lucke
Date:   Fri Oct 29 10:29:38 2021 +0200
Branches: blender-v3.0-release
https://developer.blender.org/rB7c860ab9d4b54f9c394d3c2769927f55c6737b5f

Fix T92499: duplicating geometry nodes modifier causes crash

Calling `remove_unused_references` inside the `modify_geometry_sets` loop
was known to be not entirely reliable before. Now I just moved it out of
the loop which fixes the bug.

===================================================================

M	source/blender/nodes/geometry/nodes/node_geo_instance_on_points.cc

===================================================================

diff --git a/source/blender/nodes/geometry/nodes/node_geo_instance_on_points.cc b/source/blender/nodes/geometry/nodes/node_geo_instance_on_points.cc
index f4a127faf43..1e94a4a6a50 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_instance_on_points.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_instance_on_points.cc
@@ -202,12 +202,15 @@ static void geo_node_instance_on_points_exec(GeoNodeExecParams params)
           instances, *geometry_set.get_component_for_read<CurveComponent>(), instance, params);
       geometry_set.remove(GEO_COMPONENT_TYPE_CURVE);
     }
-    /* Unused references may have been added above. Remove those now so that other nodes don't
-     * process them needlessly. */
-    /** \note: This currently expects that all originally existing instances were used. */
-    instances.remove_unused_references();
   });
 
+  /* Unused references may have been added above. Remove those now so that other nodes don't
+   * process them needlessly.
+   * This should eventually be moved into the loop above, but currently this is quite tricky
+   * because it might remove references that the loop still wants to iterate over. */
+  InstancesComponent &instances = geometry_set.get_component_for_write<InstancesComponent>();
+  instances.remove_unused_references();
+
   params.set_output("Instances", std::move(geometry_set));
 }