QA·C Help - 3946

	3946	unsigned short value returned from unsigned char %s().

Arithmetic type - Implicit conversions

An expression of type unsigned short is being implicitly converted to a type of lower rank, unsigned char. This will result in a loss of information unless the 2 types happen to be implemented in the same number of bits.

Implicit type conversions of this nature can occur in the context of:

initializations
assignment operations
the passing of a function argument
the return of a value from a function

Make sure that you are aware of the type sizes that are implemented when this code is compiled and ensure that QA·C is appropriately configured to be consistent. Type sizes in QA·C are configured using the -size option (compiler personality).

By default, this message will only be generated if the 2 types are configured to be of different size; but, if the -strictrank+ option is applied, the message will always be generated, even if the types are "equivalent" - i.e. configured to be the same size. The strictrank option is configured in the analyser personality.

For example:


/*PRQA S 2017,3197,3199,3203,3227,3408,3447,3602,3625 ++*/
/**************************
 * OPTIONS: -sr+
 **************************/


extern void ef(unsigned char p);

extern unsigned char foo(unsigned short v)
{
    unsigned char a = v;        /* Message 3746 */

    a = v;                      /* Message 3746 */

    ef(v);                      /* Message 3746 */

    return v;                   /* Message 3946 */
}