MISRA.CAST.PTR.UNRELATED

Object of pointer type cast to unrelated type.

MISRA-C Rule 11.2 (required): Conversions shall not be performed between a pointer to object and any type other than an integral type, another pointer to object type or a pointer to void.

[Undefined 29]

Such conversions are undefined. This rule means that an object pointer can be converted to or from:

(a) An integral type;

(b) Another pointer to object type;

(c) A pointer to void.

No other conversions involving object pointers are permitted.

MISRA-C++ Rule 5-2-7 (required): An object with pointer type shall not be converted to an unrelated pointer type, either directly or indirectly.

[Unspecified 5.2.10(7)]

Rationale

The result of converting from a pointer to an unrelated type is unspecified.

Example

struct S
{
   int32_t i;
   int32_t j;
};
class C
{
public:
   int32_t i;
public:
   int32_t j;
   virtual ~C ( );
};
void f ( S * s )
{
   C     * c = reinterpret_cast< C * >( s );      // Non-compliant
   int32_t i = reinterpret_cast< int32_t >( s );  // Compliant, but
                                                  // breaks Rule 5—2—9
   C     * d = reinterpret_cast< C * >( i );      // Non-compliant
   S     * e = reinterpret_cast< S * >( i );      // Compliant, but
                                                  // breaks Rule 5—2—8
}