34ac393f76bda366a8ad142ff4d568ba3465bb25
2 * SPDX-License-Identifier: MIT
4 * Copyright 2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
7 #ifndef _BABELTRACE_INTERNAL_H
8 #define _BABELTRACE_INTERNAL_H
15 #define BT_EXTERN_C extern "C"
20 #define bt_max_t(type, a, b) \
21 ((type) (a) > (type) (b) ? (type) (a) : (type) (b))
24 * BT_HIDDEN: set the hidden attribute for internal functions
25 * On Windows, symbols are local unless explicitly exported,
26 * see https://gcc.gnu.org/wiki/Visibility
28 #if defined(_WIN32) || defined(__CYGWIN__)
31 #define BT_HIDDEN __attribute__((visibility("hidden")))
35 * Yield `ref`'s value while setting `ref` to NULL.
37 * This can be used to give a strong reference to a callee:
39 * add_foo_to_list(list, BT_MOVE_REF(foo));
41 * or in a simple assignment:
43 * my_struct->foo = BT_MOVE_REF(foo);
45 * When moving a reference in a function call, the reference is given to the
46 * callee even if that function call fails, so make sure the called function
47 * is written accordingly.
50 #define BT_MOVE_REF(ref) \
52 __typeof__(ref) _ref = ref; \
59 * <https://stackoverflow.com/questions/37411809/how-to-elegantly-fix-this-unused-variable-warning/37412551#37412551>:
61 * * sizeof() ensures that the expression is not evaluated at all, so
62 * its side-effects don't happen. That is to be consistent with the
63 * usual behaviour of debug-only constructs, such as assert().
65 * * `((_expr), 0)` uses the comma operator to swallow the actual type
66 * of `(_expr)`. This is to prevent VLAs from triggering evaluation.
68 * * `(void)` explicitly ignores the result of `(_expr)` and sizeof() so
69 * no "unused value" warning appears.
72 #define BT_USE_EXPR(_expr) ((void) sizeof((void) (_expr), 0))
73 #define BT_USE_EXPR2(_expr1, _expr2) \
74 ((void) sizeof((void) (_expr1), (void) (_expr2), 0))
75 #define BT_USE_EXPR3(_expr1, _expr2, _expr3) \
76 ((void) sizeof((void) (_expr1), (void) (_expr2), (void) (_expr3), 0))
77 #define BT_USE_EXPR4(_expr1, _expr2, _expr3, _expr4) \
78 ((void) sizeof((void) (_expr1), (void) (_expr2), \
79 (void) (_expr3), (void) (_expr4), 0))
80 #define BT_USE_EXPR5(_expr1, _expr2, _expr3, _expr4, _expr5) \
81 ((void) sizeof((void) (_expr1), (void) (_expr2), \
82 (void) (_expr3), (void) (_expr4), (void) (_expr5), 0))
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