1/*	$NetBSD: msg_166.c,v 1.6 2024/06/08 06:37:06 rillig Exp $	*/
2# 3 "msg_166.c"
3
4// Test for message: precision lost in bit-field assignment [166]
5
6/* lint1-extra-flags: -hp -X 351 */
7
8struct bit_set {
9
10	/*
11	 * C99 6.7.2p5 and 6.7.2.1p9 footnote 104 say that for bit-fields of
12	 * underlying type 'int', "it is implementation-defined whether the
13	 * specifier 'int' designates the same type as 'signed int' or the
14	 * same type as 'unsigned int'".
15	 *
16	 * https://gcc.gnu.org/onlinedocs/gcc/Structures-unions-enumerations
17	 * -and-bit-fields-implementation.html says: "By default it is treated
18	 * as 'signed int' but this may be changed by the
19	 * '-funsigned-bitfields' option".
20	 *
21	 * Clang doesn't document implementation-defined behavior, see
22	 * https://bugs.llvm.org/show_bug.cgi?id=11272.
23	 */
24
25	/* expect+1: warning: bit-field of type plain 'int' has implementation-defined signedness [344] */
26	int minus_1_to_0: 1;
27	/* expect+1: warning: bit-field of type plain 'int' has implementation-defined signedness [344] */
28	int minus_8_to_7: 4;
29	unsigned zero_to_1: 1;
30	unsigned zero_to_15: 4;
31};
32
33void example(void) {
34	struct bit_set bits;
35
36	/* Clang doesn't warn about the 1. */
37	/* expect+1: warning: precision lost in bit-field assignment [166] */
38	bits.minus_1_to_0 = -2;
39	bits.minus_1_to_0 = -1;
40	bits.minus_1_to_0 = 0;
41	/* expect+1: warning: precision lost in bit-field assignment [166] */
42	bits.minus_1_to_0 = 1;
43	/* expect+1: warning: precision lost in bit-field assignment [166] */
44	bits.minus_1_to_0 = 2;
45
46	/* expect+1: warning: precision lost in bit-field assignment [166] */
47	bits.minus_8_to_7 = -9;
48	bits.minus_8_to_7 = -8;
49	bits.minus_8_to_7 = 7;
50	/* expect+1: warning: precision lost in bit-field assignment [166] */
51	bits.minus_8_to_7 = 8;
52
53	/* Clang doesn't warn about the -1. */
54	/* expect+1: warning: assignment of negative constant -2 to unsigned type 'unsigned int:1' [164] */
55	bits.zero_to_1 = -2;
56	/* expect+1: warning: assignment of negative constant -1 to unsigned type 'unsigned int:1' [164] */
57	bits.zero_to_1 = -1;
58	bits.zero_to_1 = 0;
59	bits.zero_to_1 = 1;
60	/* expect+1: warning: precision lost in bit-field assignment [166] */
61	bits.zero_to_1 = 2;
62
63	/* Clang doesn't warn about the -8. */
64	/* expect+1: warning: assignment of negative constant -9 to unsigned type 'unsigned int:4' [164] */
65	bits.zero_to_15 = -9;
66	/* expect+1: warning: assignment of negative constant -8 to unsigned type 'unsigned int:4' [164] */
67	bits.zero_to_15 = -8;
68	bits.zero_to_15 = 0;
69	bits.zero_to_15 = 15;
70	/* expect+1: warning: precision lost in bit-field assignment [166] */
71	bits.zero_to_15 = 16;
72}
73