diff --git a/ThirdParty/sundials/src/sundials/sundials_iterative_impl.h b/ThirdParty/sundials/src/sundials/sundials_iterative_impl.h
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index 0000000000..ea6c17c10e
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+++ b/ThirdParty/sundials/src/sundials/sundials_iterative_impl.h
@@ -0,0 +1,40 @@
+/* -----------------------------------------------------------------------------
+ * Programmer(s): David J. Gardner and Shelby Lockhart @ LLNL
+ * -----------------------------------------------------------------------------
+ * SUNDIALS Copyright Start
+ * Copyright (c) 2002-2024, Lawrence Livermore National Security
+ * and Southern Methodist University.
+ * All rights reserved.
+ *
+ * See the top-level LICENSE and NOTICE files for details.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ * SUNDIALS Copyright End
+ * -----------------------------------------------------------------------------
+ * This is the implementation header file for SUNDIALS functions used by
+ * different iterative solvers.
+ * ---------------------------------------------------------------------------*/
+
+#ifndef _SUNDIALS_ITERATIVE_IMPL_H
+#define _SUNDIALS_ITERATIVE_IMPL_H
+
+#include <sundials/sundials_iterative.h>
+
+/* -----------------------------------------------------------------------------
+ * Type: SUNQRData
+ * -----------------------------------------------------------------------------
+ * A SUNQRData struct holds temporary workspace vectors and sunrealtype arrays for
+ * a SUNQRAddFn. The N_Vectors and sunrealtype arrays it contains are created by
+ * the routine calling a SUNQRAdd function.
+ * ---------------------------------------------------------------------------*/
+
+typedef struct _SUNQRData* SUNQRData;
+
+struct _SUNQRData
+{
+  N_Vector vtemp;
+  N_Vector vtemp2;
+  sunrealtype* temp_array;
+};
+
+#endif