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msg_324.c revision 1.3 
      1  1.3  rillig /*	$NetBSD: msg_324.c,v 1.3 2021/01/05 23:20:53 rillig Exp $	*/
      2  1.1  rillig # 3 "msg_324.c"
      3  1.1  rillig 
      4  1.1  rillig // Test for message: suggest cast from '%s' to '%s' on op %s to avoid overflow [324]
      5  1.1  rillig 
      6  1.2  rillig /*
      7  1.2  rillig  * This warning applies to binary operators if the result of the operator
      8  1.2  rillig  * is converted to a type that is bigger than the operands' result type
      9  1.2  rillig  * after the usual arithmetic promotions.
     10  1.2  rillig  *
     11  1.2  rillig  * In such a case, the operator's result would be truncated to the operator's
     12  1.2  rillig  * result type (invoking undefined behavior for signed integers), and that
     13  1.2  rillig  * truncated value would then be converted.  At that point, a few bits may
     14  1.2  rillig  * have been lost.
     15  1.2  rillig  */
     16  1.2  rillig 
     17  1.2  rillig /* lint1-flags: -g -S -w -P */
     18  1.2  rillig 
     19  1.2  rillig void
     20  1.2  rillig example(char c, int i, unsigned u)
     21  1.2  rillig {
     22  1.2  rillig 	long l;
     23  1.2  rillig 	unsigned long ul;
     24  1.2  rillig 
     25  1.2  rillig 	l = c + i;
     26  1.2  rillig 	l = i - c;
     27  1.2  rillig 	ul = c * u;
     28  1.2  rillig 	ul = u + c;
     29  1.2  rillig 	ul = i - u;
     30  1.2  rillig 	ul = u * i;
     31  1.2  rillig 	l = i << c;
     32  1.2  rillig 
     33  1.2  rillig 	/*
     34  1.2  rillig 	 * The operators SHR, DIV and MOD cannot produce an overflow,
     35  1.2  rillig 	 * therefore no warning is necessary for them.
     36  1.2  rillig 	 */
     37  1.2  rillig 	l = i >> c;
     38  1.2  rillig 	ul = u / c;
     39  1.2  rillig 	ul = u % c;
     40  1.3  rillig 
     41  1.3  rillig 	/*
     42  1.3  rillig 	 * Assigning the result of an increment or decrement operator to a
     43  1.3  rillig 	 * differently-sized type is no unusual that there is no need to warn
     44  1.3  rillig 	 * about it.  It's also more unlikely that there is an actual loss
     45  1.3  rillig 	 * since this only happens for a single value of the old type, unlike
     46  1.3  rillig 	 * "ul = u * u", which has many more possibilities for overflowing.
     47  1.3  rillig 	 */
     48  1.3  rillig 	ul = u++;
     49  1.3  rillig 	ul = ++u;
     50  1.3  rillig 	ul = u--;
     51  1.3  rillig 	ul = --u;
     52  1.2  rillig }
     53