Fix T54098: Crash existing /w dyntopo sculpt

Optionally don't remap indices for objects.

Checking all objects parent's would reference a freed pointer
while freeing all objects.

In the case of dynamic topology there is no use in keeping track
of hook/vertex-parent indices.

Also disable this when creating meshes for undo storage
since adding an undo step shouldn't be modifying other objects.

8 files changed, 30 insertions, 6 deletions

diff --git a/source/blender/blenkernel/intern/scene.c b/source/blender/blenkernel/intern/scene.c
index 126761ed14b..423ed2af057 100644
--- a/source/blender/blenkernel/intern/scene.c
+++ b/source/blender/blenkernel/intern/scene.c
@@ -1851,7 +1851,11 @@ static void prepare_mesh_for_viewport_render(Main *bmain, Scene *scene)
 		{
 			if (check_rendered_viewport_visible(bmain)) {
 				BMesh *bm = mesh->edit_btmesh->bm;
-				BM_mesh_bm_to_me(bm, mesh, (&(struct BMeshToMeshParams){0}));
+				BM_mesh_bm_to_me(
+				        bm, mesh,
+				        (&(struct BMeshToMeshParams){
+				            .calc_object_remap = true,
+				        }));
 				DAG_id_tag_update(&mesh->id, 0);
 			}
 		}
diff --git a/source/blender/bmesh/intern/bmesh_mesh_conv.c b/source/blender/bmesh/intern/bmesh_mesh_conv.c
index 7787d704b59..4b86ac03d7f 100644
--- a/source/blender/bmesh/intern/bmesh_mesh_conv.c
+++ b/source/blender/bmesh/intern/bmesh_mesh_conv.c
@@ -751,7 +751,7 @@ void BM_mesh_bm_to_me(
 	}
 
 	/* patch hook indices and vertex parents */
-	if (ototvert > 0) {
+	if (params->calc_object_remap && (ototvert > 0)) {
 		Object *ob;
 		ModifierData *md;
 		BMVert **vertMap = NULL;
diff --git a/source/blender/bmesh/intern/bmesh_mesh_conv.h b/source/blender/bmesh/intern/bmesh_mesh_conv.h
index 1974d364171..e6072f7b5f2 100644
--- a/source/blender/bmesh/intern/bmesh_mesh_conv.h
+++ b/source/blender/bmesh/intern/bmesh_mesh_conv.h
@@ -56,6 +56,8 @@ ATTR_NONNULL(1, 3);
 
 struct BMeshToMeshParams {
 	uint calc_tessface : 1;
+	/** Update object hook indices & vertex parents. */
+	uint calc_object_remap : 1;
 	int64_t cd_mask_extra;
 };
 void BM_mesh_bm_to_me(
diff --git a/source/blender/bmesh/operators/bmo_mesh_conv.c b/source/blender/bmesh/operators/bmo_mesh_conv.c
index 0eb9bf90ca8..981930705b3 100644
--- a/source/blender/bmesh/operators/bmo_mesh_conv.c
+++ b/source/blender/bmesh/operators/bmo_mesh_conv.c
@@ -72,5 +72,10 @@ void bmo_bmesh_to_mesh_exec(BMesh *bm, BMOperator *op)
 	/* Object *ob = BMO_slot_ptr_get(op, "object"); */
 	const bool dotess = !BMO_slot_bool_get(op->slots_in, "skip_tessface");
 
-	BM_mesh_bm_to_me(bm, me, (&(struct BMeshToMeshParams){ .calc_tessface = dotess, }));
+	BM_mesh_bm_to_me(
+	        bm, me,
+	        (&(struct BMeshToMeshParams){
+	            .calc_tessface = dotess,
+	            .calc_object_remap = true,
+	        }));
 }
diff --git a/source/blender/editors/mesh/editmesh_tools.c b/source/blender/editors/mesh/editmesh_tools.c
index 4b4f1b2afea..c979a73e964 100644
--- a/source/blender/editors/mesh/editmesh_tools.c
+++ b/source/blender/editors/mesh/editmesh_tools.c
@@ -3357,7 +3357,11 @@ static int edbm_separate_exec(bContext *C, wmOperator *op)
 					}
 
 					if (retval_iter) {
-						BM_mesh_bm_to_me(bm_old, me, (&(struct BMeshToMeshParams){0}));
+						BM_mesh_bm_to_me(
+						        bm_old, me,
+						        (&(struct BMeshToMeshParams){
+						            .calc_object_remap = true,
+						        }));
 
 						DAG_id_tag_update(&me->id, OB_RECALC_DATA);
 						WM_event_add_notifier(C, NC_GEOM | ND_DATA, me);
diff --git a/source/blender/editors/mesh/editmesh_undo.c b/source/blender/editors/mesh/editmesh_undo.c
index 534ca22178e..11667ed5710 100644
--- a/source/blender/editors/mesh/editmesh_undo.c
+++ b/source/blender/editors/mesh/editmesh_undo.c
@@ -496,6 +496,8 @@ static void *editbtMesh_to_undoMesh(void *emv, void *obdata)
 
 	BM_mesh_bm_to_me(
 	        em->bm, &um->me, (&(struct BMeshToMeshParams){
+	            /* Undo code should not be manipulating 'G.main->object' hooks/vertex-parent. */
+	            .calc_object_remap = false,
 	            .cd_mask_extra = CD_MASK_SHAPE_KEYINDEX,
 	        }));
 
diff --git a/source/blender/editors/mesh/editmesh_utils.c b/source/blender/editors/mesh/editmesh_utils.c
index e407d342603..c4440fa190a 100644
--- a/source/blender/editors/mesh/editmesh_utils.c
+++ b/source/blender/editors/mesh/editmesh_utils.c
@@ -380,7 +380,10 @@ void EDBM_mesh_load(Object *ob)
 		bm->shapenr = 1;
 	}
 
-	BM_mesh_bm_to_me(bm, me, (&(struct BMeshToMeshParams){0}));
+	BM_mesh_bm_to_me(
+	        bm, me, (&(struct BMeshToMeshParams){
+	            .calc_object_remap = true,
+	        }));
 
 #ifdef USE_TESSFACE_DEFAULT
 	BKE_mesh_tessface_calc(me);
diff --git a/source/blender/python/bmesh/bmesh_py_types.c b/source/blender/python/bmesh/bmesh_py_types.c
index 6ab5ebf3c81..2866683b89b 100644
--- a/source/blender/python/bmesh/bmesh_py_types.c
+++ b/source/blender/python/bmesh/bmesh_py_types.c
@@ -904,7 +904,11 @@ static PyObject *bpy_bmesh_to_mesh(BPy_BMesh *self, PyObject *args)
 	/* python won't ensure matching uv/mtex */
 	BM_mesh_cd_validate(bm);
 
-	BM_mesh_bm_to_me(bm, me, (&(struct BMeshToMeshParams){0}));
+	BM_mesh_bm_to_me(
+	        bm, me,
+	        (&(struct BMeshToMeshParams){
+	            .calc_object_remap = true,
+	        }));
 
 	/* we could have the user do this but if they forget blender can easy crash
 	 * since the references arrays for the objects derived meshes are now invalid */