Fix T61353: Crash converting a curve to a mesh

This was caused by curves pointing to each other
creating a cyclic dependency.

While the dependency graph detects this, generating a mesh for render
recursively generates data which cashes in this case.

Add in a check to detect cyclic links.

Note, this bug exists in 2.7x too - but only crashes on render
since 2.7x didn't use 'for_render' when converting data.

1 files changed, 1 insertions, 1 deletions

diff --git a/source/blender/editors/object/object_modifier.c b/source/blender/editors/object/object_modifier.c
index d6aa74da273..c91173d95ca 100644
--- a/source/blender/editors/object/object_modifier.c
+++ b/source/blender/editors/object/object_modifier.c
@@ -105,7 +105,7 @@ static void object_force_modifier_update_for_bind(Depsgraph *depsgraph, Scene *s
 		BKE_displist_make_mball(depsgraph, scene, ob);
 	}
 	else if (ELEM(ob->type, OB_CURVE, OB_SURF, OB_FONT)) {
-		BKE_displist_make_curveTypes(depsgraph, scene, ob, false, false);
+		BKE_displist_make_curveTypes(depsgraph, scene, ob, false, false, NULL);
 	}
 }