gcc_attribute_var.c revision 1.4 
1/*	$NetBSD: gcc_attribute_var.c,v 1.4 2021/08/11 05:08:35 rillig Exp $	*/
2# 3 "gcc_attribute_var.c"
3
4/*
5 * Tests for the GCC __attribute__ for variables.
6 *
7 * https://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html
8 */
9
10void
11write_to_page(unsigned index, char ch)
12{
13	static char page[4096]
14	    __attribute__((__aligned__(4096)));
15
16	page[index] = ch;
17}
18
19void
20placement(
21    __attribute__((__deprecated__)) int before,
22    int __attribute__((__deprecated__)) between,
23    int after __attribute__((__deprecated__))
24);
25
26void println(void);
27
28/*
29 * Since cgram.y 1.294 from 2021-07-10, lint did not accept declarations that
30 * started with __attribute__, due to a newly and accidentally introduced
31 * shift/reduce conflict in the grammar.
32 *
33 * A GCC extension allows statement of the form __attribute__((fallthrough)),
34 * thus starting with __attribute__.  This is the 'shift' in the conflict.
35 * The 'reduce' in the conflict was begin_type.
36 *
37 * Before cgram 1.294, the gcc_attribute was placed outside the pair of
38 * begin_type/end_type, exactly to resolve this conflict.
39 *
40 * Conceptually, it made sense to put the __attribute__((unused)) between
41 * begin_type and end_type, to make it part of the declaration-specifiers.
42 * This change introduced the hidden conflict though.
43 *
44 * Interestingly, the number of shift/reduce conflicts did not change in
45 * cgram 1.294, the conflicts were just resolved differently than before.
46 *
47 * To prevent this from happening again, make sure that declarations as well
48 * as statements can start with gcc_attribute.
49 */
50void
51ambiguity_for_attribute(void)
52{
53	__attribute__((unused)) _Bool var1;
54
55	switch (1) {
56	case 1:
57		println();
58		/* expect+1: warning: 'var2' unused in function 'ambiguity_for_attribute' [192] */
59		__attribute__((unused)) _Bool var2;
60		__attribute__((fallthrough));
61		case 2:
62			println();
63	}
64}
65
66void
67attribute_after_array_brackets(
68    /* FIXME: GCC accepts this */
69    /* expect+1: error: syntax error '__attribute__' [249] */
70    const char *argv[] __attribute__((__unused__))
71)
72{
73}
74
75/* just to trigger _some_ error, to keep the .exp file */
76/* expect+1: error: syntax error 'syntax_error' [249] */
77__attribute__((syntax_error));
78