Fix T54568: Undo memory de-duplication failed

Error in 651b8fb14e caused de-duplication to fail.

3 files changed, 13 insertions, 1 deletions

diff --git a/source/blender/blenkernel/BKE_undo_system.h b/source/blender/blenkernel/BKE_undo_system.h
index 9697c7dd8e2..53ea8ddefe8 100644
--- a/source/blender/blenkernel/BKE_undo_system.h
+++ b/source/blender/blenkernel/BKE_undo_system.h
@@ -149,6 +149,7 @@ bool BKE_undosys_step_push_with_type(UndoStack *ustack, struct bContext *C, cons
 bool BKE_undosys_step_push(UndoStack *ustack, struct bContext *C, const char *name);
 
 UndoStep *BKE_undosys_step_find_by_name_with_type(UndoStack *ustack, const char *name, const UndoType *ut);
+UndoStep *BKE_undosys_step_find_by_type(UndoStack *ustack, const UndoType *ut);
 UndoStep *BKE_undosys_step_find_by_name(UndoStack *ustack, const char *name);
 
 bool BKE_undosys_step_undo_with_data_ex(UndoStack *ustack, struct bContext *C, UndoStep *us, bool use_skip);
diff --git a/source/blender/blenkernel/intern/undo_system.c b/source/blender/blenkernel/intern/undo_system.c
index 760c6a60976..5a0081bff16 100644
--- a/source/blender/blenkernel/intern/undo_system.c
+++ b/source/blender/blenkernel/intern/undo_system.c
@@ -500,6 +500,16 @@ UndoStep *BKE_undosys_step_find_by_name(UndoStack *ustack, const char *name)
 	return BLI_rfindstring(&ustack->steps, name, offsetof(UndoStep, name));
 }
 
+UndoStep *BKE_undosys_step_find_by_type(UndoStack *ustack, const UndoType *ut)
+{
+	for (UndoStep *us = ustack->steps.last; us; us = us->prev) {
+		if (us->type == ut) {
+			return us;
+		}
+	}
+	return NULL;
+}
+
 bool BKE_undosys_step_undo_with_data_ex(
         UndoStack *ustack, bContext *C, UndoStep *us,
         bool use_skip)
diff --git a/source/blender/editors/undo/memfile_undo.c b/source/blender/editors/undo/memfile_undo.c
index a0f7ebac477..bb81da74f88 100644
--- a/source/blender/editors/undo/memfile_undo.c
+++ b/source/blender/editors/undo/memfile_undo.c
@@ -70,9 +70,10 @@ static bool memfile_undosys_step_encode(struct bContext *C, UndoStep *us_p)
 
 	/* Important we only use 'main' from the context (see: BKE_undosys_stack_init_from_main). */
 	struct Main *bmain = CTX_data_main(C);
+	UndoStack *ustack = ED_undo_stack_get();
 
 	/* can be NULL, use when set. */
-	MemFileUndoStep *us_prev = (MemFileUndoStep *)BKE_undosys_step_same_type_prev(us_p);
+	MemFileUndoStep *us_prev = (MemFileUndoStep *)BKE_undosys_step_find_by_type(ustack, BKE_UNDOSYS_TYPE_MEMFILE);
 	us->data = BKE_memfile_undo_encode(bmain, us_prev ? us_prev->data : NULL);
 	us->step.data_size = us->data->undo_size;
 	return true;