1 /* $NetBSD: msg_324.c,v 1.5 2021/01/31 11:12:07 rillig Exp $ */ 2 # 3 "msg_324.c" 3 4 // Test for message: suggest cast from '%s' to '%s' on op %s to avoid overflow [324] 5 6 /* 7 * This warning applies to binary operators if the result of the operator 8 * is converted to a type that is bigger than the operands' result type 9 * after the usual arithmetic promotions. 10 * 11 * In such a case, the operator's result would be truncated to the operator's 12 * result type (invoking undefined behavior for signed integers), and that 13 * truncated value would then be converted. At that point, a few bits may 14 * have been lost. 15 */ 16 17 /* lint1-flags: -g -S -w -P */ 18 19 void 20 example(char c, int i, unsigned u) 21 { 22 long long ll; 23 unsigned long long ull; 24 25 ll = c + i; /* expect: 324 */ 26 ll = i - c; /* expect: 324 */ 27 ull = c * u; /* expect: 324 */ 28 ull = u + c; /* expect: 324 */ 29 ull = i - u; /* expect: 324 */ 30 ull = u * i; /* expect: 324 */ 31 ll = i << c; /* expect: 324 */ 32 33 /* 34 * The operators SHR, DIV and MOD cannot produce an overflow, 35 * therefore no warning is necessary for them. 36 */ 37 ll = i >> c; 38 ull = u / c; 39 ull = u % c; 40 41 /* 42 * Assigning the result of an increment or decrement operator to a 43 * differently-sized type is no unusual that there is no need to warn 44 * about it. It's also more unlikely that there is an actual loss 45 * since this only happens for a single value of the old type, unlike 46 * "ull = u * u", which has many more possibilities for overflowing. 47 */ 48 ull = u++; 49 ull = ++u; 50 ull = u--; 51 ull = --u; 52 } 53