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, 3 insertions, 1 deletions

diff --git a/source/blender/blenkernel/BKE_curve.h b/source/blender/blenkernel/BKE_curve.h
index 236c5e8da06..fe8f9ace134 100644
--- a/source/blender/blenkernel/BKE_curve.h
+++ b/source/blender/blenkernel/BKE_curve.h
@@ -27,6 +27,7 @@ struct Curve;
 struct Depsgraph;
 struct EditNurb;
 struct GHash;
+struct LinkNode;
 struct ListBase;
 struct Main;
 struct Nurb;
@@ -119,7 +120,8 @@ void BKE_curve_bevelList_free(struct ListBase *bev);
 void BKE_curve_bevelList_make(struct Object *ob, struct ListBase *nurbs, bool for_render);
 void BKE_curve_bevel_make(
         struct Depsgraph *depsgraph, struct Scene *scene, struct Object *ob,  struct ListBase *disp,
-        const bool for_render, const bool use_render_resolution);
+        const bool for_render, const bool use_render_resolution,
+        struct LinkNode *ob_cyclic_list);
 
 void BKE_curve_forward_diff_bezier(float q0, float q1, float q2, float q3, float *p, int it, int stride);
 void BKE_curve_forward_diff_tangent_bezier(float q0, float q1, float q2, float q3, float *p, int it, int stride);