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.

3 files changed, 9 insertions, 2 deletions

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,
+	        }));
 }