[previous] 4398 [next] An expression which is the result of a ~ or << operation has been cast to a different essential type category.
Arithmetic type - Casts

This message is issued whenever a composite expression which is the result of a ~ or << operation has been cast to a different essential type category.

It is a common misconception among programmers that the type in which the bitwise operation is evaluated is influenced by the cast-to type. Instead, the type of the expression is determined solely from the type of its operands after any integral promotion. Therefore, top bits which could be represented in the cast-to type may be truncated.

For example: 


/*PRQA S 1-9999 ++*/
/*PRQA S 4398 --*/

void foo (long b);

long f4398 (unsigned short a)
{
  foo ((long) (a << 1u));   /* 4398 */

  return ((long) (~a));     /* 4398 */
}

MISRA-C:2004 Rules applicable to message 4398:

Rule  10.5  (Required) If the bitwise operators ~ and << are applied to an operand of underlying type unsigned char or unsigned short, the result shall be immediately cast to the underlying type of the operand.

QA·C Source Code Analyser 8.1
MISRA-C:2004 Compliance Module 3.2
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