-#define DT_FLAG_DESTROYED 0x0001 /**< user destroyed but some other layers still have a reference */
-#define DT_FLAG_COMMITED 0x0002 /**< ready to be used for a send/recv operation */
-#define DT_FLAG_CONTIGUOUS 0x0004 /**< contiguous datatype */
-#define DT_FLAG_OVERLAP 0x0008 /**< datatype is unpropper for a recv operation */
-#define DT_FLAG_USER_LB 0x0010 /**< has a user defined LB */
-#define DT_FLAG_USER_UB 0x0020 /**< has a user defined UB */
-#define DT_FLAG_PREDEFINED 0x0040 /**< cannot be removed: initial and predefined datatypes */
-#define DT_FLAG_NO_GAPS 0x0080 /**< no gaps around the datatype */
-#define DT_FLAG_DATA 0x0100 /**< data or control structure */
-#define DT_FLAG_ONE_SIDED 0x0200 /**< datatype can be used for one sided operations */
-#define DT_FLAG_UNAVAILABLE 0x0400 /**< datatypes unavailable on the build (OS or compiler dependant) */
-#define DT_FLAG_DERIVED 0x0800 /**< is the datatype derived ? */
+constexpr unsigned DT_FLAG_DESTROYED = 0x0001; /**< user destroyed but some other layers still have a reference */
+constexpr unsigned DT_FLAG_COMMITED = 0x0002; /**< ready to be used for a send/recv operation */
+constexpr unsigned DT_FLAG_CONTIGUOUS = 0x0004; /**< contiguous datatype */
+constexpr unsigned DT_FLAG_OVERLAP = 0x0008; /**< datatype is unproper for a recv operation */
+constexpr unsigned DT_FLAG_USER_LB = 0x0010; /**< has a user defined LB */
+constexpr unsigned DT_FLAG_USER_UB = 0x0020; /**< has a user defined UB */
+constexpr unsigned DT_FLAG_PREDEFINED = 0x0040; /**< cannot be removed: initial and predefined datatypes */
+constexpr unsigned DT_FLAG_NO_GAPS = 0x0080; /**< no gaps around the datatype */
+constexpr unsigned DT_FLAG_DATA = 0x0100; /**< data or control structure */
+constexpr unsigned DT_FLAG_ONE_SIDED = 0x0200; /**< datatype can be used for one sided operations */
+constexpr unsigned DT_FLAG_UNAVAILABLE = 0x0400; /**< datatypes unavailable on the build (OS or compiler dependent) */
+constexpr unsigned DT_FLAG_DERIVED = 0x0800; /**< is the datatype derived ? */