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msg_267.c revision 1.7 
      1 /*	$NetBSD: msg_267.c,v 1.7 2023/07/07 19:45:22 rillig Exp $	*/
      2 # 3 "msg_267.c"
      3 
      4 // Test for message: shift amount %u equals bit-size of '%s' [267]
      5 
      6 /* lint1-extra-flags: -X 351 */
      7 
      8 int
      9 shr32(unsigned int x)
     10 {
     11 	/* expect+1: warning: shift amount 32 equals bit-size of 'unsigned int' [267] */
     12 	return x >> 32;
     13 }
     14 
     15 int
     16 shl32(unsigned int x)
     17 {
     18 	/* expect+1: warning: shift amount 32 equals bit-size of 'unsigned int' [267] */
     19 	return x << 32;
     20 }
     21 
     22 /*
     23  * As of 2022-08-19, lint ignores the GCC-specific 'mode' attribute, treating
     24  * the tetra-int as a plain single-int, thus having width 32.
     25  *
     26  * https://gcc.gnu.org/onlinedocs/gccint/Machine-Modes.html
     27  */
     28 unsigned
     29 function(unsigned __attribute__((mode(TI))) arg)
     30 {
     31 	/* expect+1: warning: shift amount 32 equals bit-size of 'unsigned int' [267] */
     32 	return (arg >> 32) & 3;
     33 }
     34 
     35 unsigned
     36 shift_bit_field(void)
     37 {
     38 	struct {
     39 		unsigned bit_field:18;
     40 	} s = { 12345 };
     41 
     42 	/*
     43 	 * A warning may be useful here for '>>' with a shift amount >= 18.
     44 	 *
     45 	 * For '<<' and bit-size <= 31, a warning only makes sense for shift
     46 	 * amounts >= 31, as it is legitimate to rely on the default integer
     47 	 * promotions of the left-hand operand. The default integer promotion
     48 	 * turns the type into 'int', not 'unsigned int', therefore the 31.
     49 	 * Using the same warning text would be confusing though.
     50 	 *
     51 	 * For '<<' and bit-size == 32, the standard case applies.
     52 	 *
     53 	 * As of 2022-08-19, Clang-tidy doesn't warn about any of these.
     54 	 */
     55 	return
     56 	    (s.bit_field >> 17) &
     57 	    (s.bit_field >> 18) &
     58 	    (s.bit_field >> 19) &
     59 	    (s.bit_field >> 31) &
     60 	    /* XXX: Why 'int:18', not 'unsigned int:18'? */
     61 	    /* expect+1: warning: shift amount 32 equals bit-size of 'int:18' [267] */
     62 	    (s.bit_field >> 32) &
     63 	    /* XXX: Why 'int', not 'unsigned int:18'? */
     64 	    /* expect+1: warning: shift amount 33 is greater than bit-size 32 of 'int' [122] */
     65 	    (s.bit_field >> 33) &
     66 	    (s.bit_field << 17) &
     67 	    (s.bit_field << 18) &
     68 	    (s.bit_field << 19) &
     69 	    (s.bit_field << 31) &
     70 	    /* XXX: Why 'int:18', not 'unsigned int:18'? */
     71 	    /* expect+1: warning: shift amount 32 equals bit-size of 'int:18' [267] */
     72 	    (s.bit_field << 32) &
     73 	    /* XXX: Why 'int', not 'unsigned int:18'? */
     74 	    /* expect+1: warning: shift amount 33 is greater than bit-size 32 of 'int' [122] */
     75 	    (s.bit_field << 33) &
     76 	    15;
     77 }
     78