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d_c99_bool.c revision 1.8 
      1 /*	$NetBSD: d_c99_bool.c,v 1.8 2022/01/15 14:22:03 rillig Exp $	*/
      2 # 3 "d_c99_bool.c"
      3 
      4 /*
      5  * C99 6.3.1.2 says: "When any scalar value is converted to _Bool, the result
      6  * is 0 if the value compares equal to 0; otherwise the result is 1."
      7  *
      8  * This is different from the other integer types, which get truncated or
      9  * invoke undefined behavior.
     10  */
     11 
     12 /* Below, each false statement produces "negative array dimension" [20]. */
     13 
     14 int int_0_converts_to_false[(_Bool)0 ? -1 : 1];
     15 /* expect+1: error: negative array dimension (-1) [20] */
     16 int int_0_converts_to_true_[(_Bool)0 ? 1 : -1];
     17 
     18 /* expect+1: error: negative array dimension (-1) [20] */
     19 int int_1_converts_to_false[(_Bool)1 ? -1 : 1];
     20 int int_1_converts_to_true_[(_Bool)1 ? 1 : -1];
     21 
     22 /* expect+1: error: negative array dimension (-1) [20] */
     23 int int_2_converts_to_false[(_Bool)2 ? -1 : 1];
     24 int int_2_converts_to_true_[(_Bool)2 ? 1 : -1];
     25 
     26 /* expect+1: error: negative array dimension (-1) [20] */
     27 int int_256_converts_to_false[(_Bool)256 ? -1 : 1];
     28 int int_256_converts_to_true_[(_Bool)256 ? 1 : -1];
     29 
     30 int null_pointer_converts_to_false[(_Bool)(void *)0 ? -1 : 1];
     31 /* expect+1: error: negative array dimension (-1) [20] */
     32 int null_pointer_converts_to_true_[(_Bool)(void *)0 ? 1 : -1];
     33 
     34 /*
     35  * XXX: lint does not treat the address of a global variable as a constant
     36  * expression.  This goes against C99 6.6p7 but is probably not too relevant
     37  * in practice.
     38  *
     39  * The call to constant(tn, 0) defaults to 1, then.  This is why neither of
     40  * the following array declarations generates an error message.
     41  */
     42 char ch;
     43 int nonnull_pointer_converts_to_false[(_Bool)&ch ? -1 : 1];
     44 int nonnull_pointer_converts_to_true_[(_Bool)&ch ? 1 : -1];
     45 
     46 /* expect+1: error: negative array dimension (-1) [20] */
     47 int double_minus_1_0_converts_to_false[(_Bool)-1.0 ? -1 : 1];
     48 int double_minus_1_0_converts_to_true_[(_Bool)-1.0 ? 1 : -1];
     49 
     50 /* expect+1: error: negative array dimension (-1) [20] */
     51 int double_minus_0_5_converts_to_false[(_Bool)-0.5 ? -1 : 1];
     52 int double_minus_0_5_converts_to_true_[(_Bool)-0.5 ? 1 : -1];
     53 
     54 int double_minus_0_0_converts_to_false[(_Bool)-0.0 ? -1 : 1];
     55 /* expect+1: error: negative array dimension (-1) [20] */
     56 int double_minus_0_0_converts_to_true_[(_Bool)-0.0 ? 1 : -1];
     57 
     58 int double_0_0_converts_to_false[(_Bool)0.0 ? -1 : 1];
     59 /* expect+1: error: negative array dimension (-1) [20] */
     60 int double_0_0_converts_to_true_[(_Bool)0.0 ? 1 : -1];
     61 
     62 /* The C99 rationale explains in 6.3.1.2 why (_Bool)0.5 is true. */
     63 /* expect+1: error: negative array dimension (-1) [20] */
     64 int double_0_5_converts_to_false[(_Bool)0.5 ? -1 : 1];
     65 int double_0_5_converts_to_true_[(_Bool)0.5 ? 1 : -1];
     66 
     67 /* expect+1: error: negative array dimension (-1) [20] */
     68 int double_1_0_converts_to_false[(_Bool)1.0 ? -1 : 1];
     69 int double_1_0_converts_to_true_[(_Bool)1.0 ? 1 : -1];
     70 
     71 _Bool
     72 bool_to_bool(_Bool b)
     73 {
     74 	return b;
     75 }
     76 
     77 _Bool
     78 char_to_bool(char c)
     79 {
     80 	return c;
     81 }
     82 
     83 _Bool
     84 int_to_bool(int i)
     85 {
     86 	return i;
     87 }
     88 
     89 _Bool
     90 double_to_bool(double d)
     91 {
     92 	return d;
     93 }
     94 
     95 enum color {
     96 	RED
     97 };
     98 
     99 _Bool
    100 enum_to_bool(enum color e)
    101 {
    102 	return e;
    103 }
    104 
    105 _Bool
    106 pointer_to_bool(const char *p)
    107 {
    108 	return p;
    109 }
    110 
    111 _Bool
    112 function_pointer_to_bool(void (*f)(void))
    113 {
    114 	return f;
    115 }
    116 
    117 _Bool
    118 complex_to_bool(double _Complex c)
    119 {
    120 	return c;
    121 }
    122