问转换函数指针无效的效果是什么？

EN

typedef struct StdBuffer { void* address; } StdBuffer;
extern void StdBufferClear(StdBuffer);

typedef struct CharBuffer { char* address; } CharBuffer;
void (*CharBufferClear)(CharBuffer) = (void*) StdBufferClear;

typedef struct StdBuffer {

    size_t width;        ///< The number of bytes that complete a data unit.
    size_t limit;        ///< The maximum number of data units that can be allocated for this buffer.
    void * address;      ///< The memory address for this buffer.
    size_t index;        ///< The current unit position indicator.
    size_t allocated;    ///< The current number of allocated addressable units.
    StdBufferFlags flags;///< The API contract for this buffer.

} StdBuffer;

typedef struct CharBuffer {

    size_t width;        ///< The number of bytes that complete a data unit.
    size_t limit;        ///< The maximum number of data units that can be allocated for this buffer.
    char * address;      ///< The memory address for this buffer.
    size_t index;        ///< The current unit position indicator.
    size_t allocated;    ///< The current number of allocated addressable units.
    CharBufferFlags flags;///< The API contract for this buffer.

} CharBuffer;

/** \def BIT(I)
    \brief A macro for setting a single constant bit.
 *
 *  This macro sets the bit indicated by I to enabled.
 *  \param I the (1-based) index of the desired bit to set.
 */
 #define BIT(I) (1UL << (I - 1))

/** \enum StdBufferFlags
    \brief Flags that may be applied to all StdBuffer structures.

 *  These flags determine the contract of operations between the caller
 *  and the StdBuffer API for working with data. Bits 1-4 are for the
 *  API control functions. All other bits are undefined/don't care bits.
 *
 *  If your application would like to use the don't care bits, it would
 *  be smart not to use bits 5-8, as these may become used by the API
 *  in future revisions of the software.

*/
typedef enum StdBufferFlags {

    BUFFER_MALLOCD = BIT(1),    ///< The memory address specified by this buffer was allocated by an API
    BUFFER_WRITEABLE = BIT(2),  ///< Permission to modify buffer contents using the API
    BUFFER_READABLE = BIT(3),   ///< Permission to retrieve buffer contents using the API
    BUFFER_MOVABLE = BIT(4)     ///< Permission to resize or otherwise relocate buffer contents using the API

}StdBufferFlags;