[previous] 1893 [next] The 2nd and 3rd operands of this conditional operator are both 'essentially signed' ('%1s' and '%2s') but one is a composite expression of a narrower type than the other.
Arithmetic type - Composite expressions

This message is issued whenever a composite expression of essentially signed type has been used as the 2nd or 3rd operand of the conditional operator, and undergoes a usual arithmetic conversion to a wider signed integer type (the type of the other operand).

It is a common misconception among programmers that the type in which the narrower operand 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, an overflow may occur, which could be avoided if the operand was cast to the wider type.

For example: 


/*PRQA S 1-9999 ++*/
/*PRQA S 1893 --*/

int f1893 (short a, int b)
{
  b = (a > 0) ? (a + 1) : b;       /* 1893 */

  return ((a > 0) ? (a * 2) : b);  /* 1893 */
}

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 1893:

Rule  10.2  (Required) The value of an expression of floating type shall not be implicitly converted to a different type if: a) it is not a conversion to a wider floating type, or b) the expression is complex, or c) the expression is a function argument, or d) the expression is a return expression

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