1/*	$NetBSD: d_alignof.c,v 1.12 2023/07/07 19:45:22 rillig Exp $	*/
2# 3 "d_alignof.c"
3
4/* https://gcc.gnu.org/onlinedocs/gcc/Alignment.html */
5
6/* lint1-extra-flags: -X 351 */
7
8unsigned long
9leading_and_trailing_alignof_type(void)
10{
11	return __alignof__(short);
12}
13
14unsigned long
15leading_alignof_type(void)
16{
17	return __alignof(short);
18}
19
20unsigned long
21plain_alignof_type(void)
22{
23	/* The plain word 'alignof' is not recognized by GCC. */
24	/* expect+2: error: function 'alignof' implicitly declared to return int [215] */
25	/* expect+1: error: syntax error 'short' [249] */
26	return alignof(short);
27}
28/* expect-1: warning: function 'plain_alignof_type' falls off bottom without returning value [217] */
29
30unsigned long
31leading_and_trailing_alignof_expr(void)
32{
33	return __alignof__ 3;
34}
35
36unsigned long
37leading_alignof_expr(void)
38{
39	return __alignof 3;
40}
41
42unsigned long
43plain_alignof_expr(void)
44{
45	/* The plain word 'alignof' is not recognized by GCC. */
46	/* expect+2: error: 'alignof' undefined [99] */
47	/* expect+1: error: syntax error '3' [249] */
48	return alignof 3;
49}
50/* expect-1: warning: function 'plain_alignof_expr' falls off bottom without returning value [217] */
51
52
53/*
54 * As with 'sizeof', the keyword '__alignof__' doesn't require parentheses
55 * when followed by an expression.  This allows for the seemingly strange
56 * '->' after the parentheses, which in fact is perfectly fine.
57 *
58 * The NetBSD style guide says "We parenthesize sizeof expressions", even
59 * though it is misleading in edge cases like this.  The GCC manual says that
60 * '__alignof__' and 'sizeof' are syntactically the same, therefore the same
61 * reasoning applies to '__alignof__'.
62 */
63unsigned long
64alignof_pointer_to_member(void)
65{
66	struct s {
67		unsigned long member;
68	} var = { 0 }, *ptr = &var;
69
70	return __alignof__(ptr)->member + ptr->member;
71}
72
73void
74alignof_variants(void)
75{
76	/* expect+1: error: negative array dimension (-4) [20] */
77	typedef int array_int[-(int)__alignof(int[3])];
78
79	/* expect+1: error: negative array dimension (-8) [20] */
80	typedef int array_double[-(int)__alignof(double[3])];
81
82	/* expect+1: error: cannot take size/alignment of function type 'function(int) returning int' [144] */
83	typedef int func[-(int)__alignof(int(int))];
84
85	struct int_double {
86		int i;
87		double d;
88	};
89	/* expect+1: error: negative array dimension (-8) [20] */
90	typedef int struct_int_double[-(int)__alignof(struct int_double)];
91
92	struct chars {
93		char name[20];
94	};
95	/* expect+1: error: negative array dimension (-1) [20] */
96	typedef int struct_chars[-(int)__alignof(struct chars)];
97
98	/* expect+1: warning: struct 'incomplete_struct' never defined [233] */
99	struct incomplete_struct;
100	/* expect+1: error: cannot take size/alignment of incomplete type [143] */
101	typedef int incomplete_struct[-(int)__alignof(struct incomplete_struct)];
102
103	/* expect+1: warning: union 'incomplete_union' never defined [234] */
104	union incomplete_union;
105	/* expect+1: error: cannot take size/alignment of incomplete type [143] */
106	typedef int incomplete_union[-(int)__alignof(union incomplete_union)];
107
108	/* expect+1: warning: enum 'incomplete_enum' never defined [235] */
109	enum incomplete_enum;
110	/* expect+1: error: cannot take size/alignment of incomplete type [143] */
111	typedef int incomplete_enum[-(int)__alignof(enum incomplete_enum)];
112
113	/* expect+1: error: cannot take size/alignment of incomplete type [143] */
114	typedef int incomplete_array[-(int)__alignof(int[])];
115
116	struct bit_fields {
117		_Bool bit_field:1;
118	};
119	/*
120	 * FIXME: This is not an attempt to initialize the typedef, it's the
121	 * initialization of a nested expression.
122	 */
123	/* expect+2: error: cannot initialize typedef '00000000_tmp' [25] */
124	/* expect+1: error: cannot take size/alignment of bit-field [145] */
125	typedef int bit_field_1[-(int)__alignof((struct bit_fields){0}.bit_field)];
126
127	struct bit_fields bit_fields;
128	/* expect+1: error: cannot take size/alignment of bit-field [145] */
129	typedef int bit_field_2[-(int)__alignof(bit_fields.bit_field)];
130
131	/* expect+1: error: cannot take size/alignment of void [146] */
132	typedef int plain_void[-(int)__alignof(void)];
133}
134