xref: /netbsd-src/tests/usr.bin/xlint/lint1/d_alignof.c (revision e6298b924c5ba98f3a22919b56dab04a87cdbb1c)
1*e6298b92Srillig /*	$NetBSD: d_alignof.c,v 1.12 2023/07/07 19:45:22 rillig Exp $	*/
2aadcb6a6Srillig # 3 "d_alignof.c"
3aadcb6a6Srillig 
491bf128dSrillig /* https://gcc.gnu.org/onlinedocs/gcc/Alignment.html */
591bf128dSrillig 
6*e6298b92Srillig /* lint1-extra-flags: -X 351 */
7*e6298b92Srillig 
891bf128dSrillig unsigned long
leading_and_trailing_alignof_type(void)991bf128dSrillig leading_and_trailing_alignof_type(void)
1028604916Sjruoho {
1128604916Sjruoho 	return __alignof__(short);
1228604916Sjruoho }
1391bf128dSrillig 
1491bf128dSrillig unsigned long
leading_alignof_type(void)1591bf128dSrillig leading_alignof_type(void)
1691bf128dSrillig {
1791bf128dSrillig 	return __alignof(short);
1891bf128dSrillig }
1991bf128dSrillig 
2091bf128dSrillig unsigned long
plain_alignof_type(void)2191bf128dSrillig plain_alignof_type(void)
2291bf128dSrillig {
2391bf128dSrillig 	/* The plain word 'alignof' is not recognized by GCC. */
246300d02aSrillig 	/* expect+2: error: function 'alignof' implicitly declared to return int [215] */
256300d02aSrillig 	/* expect+1: error: syntax error 'short' [249] */
2691bf128dSrillig 	return alignof(short);
2791bf128dSrillig }
2840a9b8fdSrillig /* expect-1: warning: function 'plain_alignof_type' falls off bottom without returning value [217] */
2991bf128dSrillig 
3091bf128dSrillig unsigned long
leading_and_trailing_alignof_expr(void)3191bf128dSrillig leading_and_trailing_alignof_expr(void)
3291bf128dSrillig {
3391bf128dSrillig 	return __alignof__ 3;
3491bf128dSrillig }
3591bf128dSrillig 
3691bf128dSrillig unsigned long
leading_alignof_expr(void)3791bf128dSrillig leading_alignof_expr(void)
3891bf128dSrillig {
3991bf128dSrillig 	return __alignof 3;
4091bf128dSrillig }
4191bf128dSrillig 
4291bf128dSrillig unsigned long
plain_alignof_expr(void)4391bf128dSrillig plain_alignof_expr(void)
4491bf128dSrillig {
4591bf128dSrillig 	/* The plain word 'alignof' is not recognized by GCC. */
466300d02aSrillig 	/* expect+2: error: 'alignof' undefined [99] */
4791bf128dSrillig 	/* expect+1: error: syntax error '3' [249] */
4891bf128dSrillig 	return alignof 3;
4991bf128dSrillig }
5040a9b8fdSrillig /* expect-1: warning: function 'plain_alignof_expr' falls off bottom without returning value [217] */
51c1ebf8f4Srillig 
52c1ebf8f4Srillig 
53c1ebf8f4Srillig /*
54c1ebf8f4Srillig  * As with 'sizeof', the keyword '__alignof__' doesn't require parentheses
55c1ebf8f4Srillig  * when followed by an expression.  This allows for the seemingly strange
56c1ebf8f4Srillig  * '->' after the parentheses, which in fact is perfectly fine.
57c1ebf8f4Srillig  *
58c1ebf8f4Srillig  * The NetBSD style guide says "We parenthesize sizeof expressions", even
59c1ebf8f4Srillig  * though it is misleading in edge cases like this.  The GCC manual says that
60c1ebf8f4Srillig  * '__alignof__' and 'sizeof' are syntactically the same, therefore the same
61c1ebf8f4Srillig  * reasoning applies to '__alignof__'.
62c1ebf8f4Srillig  */
63c1ebf8f4Srillig unsigned long
alignof_pointer_to_member(void)64c1ebf8f4Srillig alignof_pointer_to_member(void)
65c1ebf8f4Srillig {
66c1ebf8f4Srillig 	struct s {
67c1ebf8f4Srillig 		unsigned long member;
68c1ebf8f4Srillig 	} var = { 0 }, *ptr = &var;
69c1ebf8f4Srillig 
70c1ebf8f4Srillig 	return __alignof__(ptr)->member + ptr->member;
71c1ebf8f4Srillig }
72bf86468dSrillig 
73bf86468dSrillig void
alignof_variants(void)74bf86468dSrillig alignof_variants(void)
75bf86468dSrillig {
76bf86468dSrillig 	/* expect+1: error: negative array dimension (-4) [20] */
77bf86468dSrillig 	typedef int array_int[-(int)__alignof(int[3])];
78bf86468dSrillig 
79bf86468dSrillig 	/* expect+1: error: negative array dimension (-8) [20] */
80bf86468dSrillig 	typedef int array_double[-(int)__alignof(double[3])];
81bf86468dSrillig 
82bf86468dSrillig 	/* expect+1: error: cannot take size/alignment of function type 'function(int) returning int' [144] */
83bf86468dSrillig 	typedef int func[-(int)__alignof(int(int))];
84bf86468dSrillig 
85bf86468dSrillig 	struct int_double {
86bf86468dSrillig 		int i;
87bf86468dSrillig 		double d;
88bf86468dSrillig 	};
89bf86468dSrillig 	/* expect+1: error: negative array dimension (-8) [20] */
90bf86468dSrillig 	typedef int struct_int_double[-(int)__alignof(struct int_double)];
91bf86468dSrillig 
92bf86468dSrillig 	struct chars {
93bf86468dSrillig 		char name[20];
94bf86468dSrillig 	};
95bf86468dSrillig 	/* expect+1: error: negative array dimension (-1) [20] */
96bf86468dSrillig 	typedef int struct_chars[-(int)__alignof(struct chars)];
97bf86468dSrillig 
98bf86468dSrillig 	/* expect+1: warning: struct 'incomplete_struct' never defined [233] */
99bf86468dSrillig 	struct incomplete_struct;
100bf86468dSrillig 	/* expect+1: error: cannot take size/alignment of incomplete type [143] */
101bf86468dSrillig 	typedef int incomplete_struct[-(int)__alignof(struct incomplete_struct)];
102bf86468dSrillig 
103bf86468dSrillig 	/* expect+1: warning: union 'incomplete_union' never defined [234] */
104bf86468dSrillig 	union incomplete_union;
105bf86468dSrillig 	/* expect+1: error: cannot take size/alignment of incomplete type [143] */
106bf86468dSrillig 	typedef int incomplete_union[-(int)__alignof(union incomplete_union)];
107bf86468dSrillig 
108bf86468dSrillig 	/* expect+1: warning: enum 'incomplete_enum' never defined [235] */
109bf86468dSrillig 	enum incomplete_enum;
1109ae9809bSrillig 	/* expect+1: error: cannot take size/alignment of incomplete type [143] */
111bf86468dSrillig 	typedef int incomplete_enum[-(int)__alignof(enum incomplete_enum)];
112bf86468dSrillig 
113fc9c97faSrillig 	/* expect+1: error: cannot take size/alignment of incomplete type [143] */
114fc9c97faSrillig 	typedef int incomplete_array[-(int)__alignof(int[])];
115fc9c97faSrillig 
116bf86468dSrillig 	struct bit_fields {
117bf86468dSrillig 		_Bool bit_field:1;
118bf86468dSrillig 	};
119bf86468dSrillig 	/*
120bf86468dSrillig 	 * FIXME: This is not an attempt to initialize the typedef, it's the
121bf86468dSrillig 	 * initialization of a nested expression.
122bf86468dSrillig 	 */
123bf86468dSrillig 	/* expect+2: error: cannot initialize typedef '00000000_tmp' [25] */
124bf86468dSrillig 	/* expect+1: error: cannot take size/alignment of bit-field [145] */
125fc9c97faSrillig 	typedef int bit_field_1[-(int)__alignof((struct bit_fields){0}.bit_field)];
126fc9c97faSrillig 
127fc9c97faSrillig 	struct bit_fields bit_fields;
128fc9c97faSrillig 	/* expect+1: error: cannot take size/alignment of bit-field [145] */
129fc9c97faSrillig 	typedef int bit_field_2[-(int)__alignof(bit_fields.bit_field)];
130bf86468dSrillig 
131bf86468dSrillig 	/* expect+1: error: cannot take size/alignment of void [146] */
132bf86468dSrillig 	typedef int plain_void[-(int)__alignof(void)];
133bf86468dSrillig }
134