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eb31c5e6 | 1 | /* |
0235b0db | 2 | * SPDX-License-Identifier: MIT |
eb31c5e6 | 3 | * |
0235b0db | 4 | * Copyright 2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
eb31c5e6 | 5 | */ |
fd3c708f | 6 | |
0235b0db MJ |
7 | #ifndef _BABELTRACE_INTERNAL_H |
8 | #define _BABELTRACE_INTERNAL_H | |
70bd0a12 | 9 | |
91d81473 | 10 | #define bt_max_t(type, a, b) \ |
f3e4505b | 11 | ((type) (a) > (type) (b) ? (type) (a) : (type) (b)) |
f3e4505b | 12 | |
5d6c80a5 JD |
13 | /* |
14 | * BT_HIDDEN: set the hidden attribute for internal functions | |
675860f4 MJ |
15 | * On Windows, symbols are local unless explicitly exported, |
16 | * see https://gcc.gnu.org/wiki/Visibility | |
5d6c80a5 | 17 | */ |
675860f4 MJ |
18 | #if defined(_WIN32) || defined(__CYGWIN__) |
19 | #define BT_HIDDEN | |
20 | #else | |
5d6c80a5 | 21 | #define BT_HIDDEN __attribute__((visibility("hidden"))) |
675860f4 | 22 | #endif |
5d6c80a5 | 23 | |
55b71f05 SM |
24 | /* |
25 | * Yield `ref`'s value while setting `ref` to NULL. | |
26 | * | |
27 | * This can be used to give a strong reference to a callee: | |
28 | * | |
29 | * add_foo_to_list(list, BT_MOVE_REF(foo)); | |
30 | * | |
31 | * or in a simple assignment: | |
32 | * | |
33 | * my_struct->foo = BT_MOVE_REF(foo); | |
34 | * | |
35 | * When moving a reference in a function call, the reference is given to the | |
36 | * callee even if that function call fails, so make sure the called function | |
37 | * is written accordingly. | |
38 | */ | |
39 | ||
40 | #define BT_MOVE_REF(ref) \ | |
41 | ({ \ | |
e3d110d6 | 42 | typeof(ref) _ref = ref; \ |
55b71f05 SM |
43 | ref = NULL; \ |
44 | _ref; \ | |
45 | }) | |
46 | ||
1778c2a4 PP |
47 | /* |
48 | * Copied from: | |
49 | * <https://stackoverflow.com/questions/37411809/how-to-elegantly-fix-this-unused-variable-warning/37412551#37412551>: | |
50 | * | |
51 | * * sizeof() ensures that the expression is not evaluated at all, so | |
52 | * its side-effects don't happen. That is to be consistent with the | |
53 | * usual behaviour of debug-only constructs, such as assert(). | |
54 | * | |
55 | * * `((_expr), 0)` uses the comma operator to swallow the actual type | |
56 | * of `(_expr)`. This is to prevent VLAs from triggering evaluation. | |
57 | * | |
58 | * * `(void)` explicitly ignores the result of `(_expr)` and sizeof() so | |
59 | * no "unused value" warning appears. | |
60 | */ | |
61 | ||
62 | #define BT_USE_EXPR(_expr) ((void) sizeof((void) (_expr), 0)) | |
63 | #define BT_USE_EXPR2(_expr1, _expr2) \ | |
64 | ((void) sizeof((void) (_expr1), (void) (_expr2), 0)) | |
65 | #define BT_USE_EXPR3(_expr1, _expr2, _expr3) \ | |
66 | ((void) sizeof((void) (_expr1), (void) (_expr2), (void) (_expr3), 0)) | |
67 | #define BT_USE_EXPR4(_expr1, _expr2, _expr3, _expr4) \ | |
68 | ((void) sizeof((void) (_expr1), (void) (_expr2), \ | |
69 | (void) (_expr3), (void) (_expr4), 0)) | |
70 | #define BT_USE_EXPR5(_expr1, _expr2, _expr3, _expr4, _expr5) \ | |
71 | ((void) sizeof((void) (_expr1), (void) (_expr2), \ | |
72 | (void) (_expr3), (void) (_expr4), (void) (_expr5), 0)) | |
73 | ||
70bd0a12 | 74 | #endif |