MISRA.FUNC_CAST

Functional notation cast different from explicit constructor call

MISRA-C++ Rule 5-2-4 (required): C-style casts (other than void casts) and functional notation casts (other than explicit constructor calls) shall not be used.

This rule is also covered by MISRA.C_CAST.

Rationale

C-style (cast notation), and functional notation casts that do not invoke a converting constructor are capable of performing casts between unrelated types.

Exception

A C-style cast to void may be used to signify that the return value for a non-void function call is being ignored (see Rule 0—1—7).

Example

class A
{
public:
   explicit A( int32_t );
};
int32_t g ( )
{
   return 7;
}
void f ( )
{
   A const a1 = A( 10 );             // Compliant
   A * a2 = ( A* )( &a1 );           // Non-compliant
   A * a3 = const_cast<A*>( &a1 );   // Compliant, but breaks Rule 5—2—5
   (void)g ( );                      // Compliant by exception
}

In the above example, the C-style cast from 'a1' to a non-const pointer is stronger than necessary. If the type of 'a1' is changed at some future date, then the cast may continue to compile.