[previous] 4499 [next] An expression which is the result of a ~ or << operation has been converted to a wider essential type on assignment.
Arithmetic type - Assignment

This message is issued whenever a composite expression which is the result of a ~ or << operation undergoes an assigning conversion to a wider essential type.

It is a common misconception among programmers that the type in which the bitwise operation is evaluated is influenced by the wider 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 wider type may be truncated.

For example: 


/*PRQA S 1-9999 ++*/
/*PRQA S 4499 --*/

void foo (unsigned b);

unsigned f4499 (unsigned short a)
{
  unsigned uia = (a << 1);  /* 4499 */

  foo (a << 1);             /* 4499 */

  uia = (~a);               /* 4499 */

  return (~a);              /* 4499 */
}

For the purposes of QAC conversion messages, types are ordered according to the configured size (-s option), by default; hence for a typical 32 bit configuration, types int and long will be considered equivalent. However, when the -strictrank option is specified, types will be ordered according to their rank; consequently int will be considered narrower than long.

MISRA-C:2004 Rules applicable to message 4499:

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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