src/common/assert.h

   1 /*
   2  * SPDX-License-Identifier: MIT
   3  *
   4  * Copyright (c) 2018-2019 EfficiOS Inc. and Linux Foundation
   5  * Copyright (c) 2018-2019 Philippe Proulx <pproulx@efficios.com>
   6  */
   7
   8 #ifndef BABELTRACE_ASSERT_INTERNAL_H
   9 #define BABELTRACE_ASSERT_INTERNAL_H
  10
  11 #include <assert.h>
  12 #include <glib.h>
  13
  14 #include "common/macros.h"
  15
  16 BT_HIDDEN
  17 extern void bt_common_assert_failed(const char *file, int line,
  18                 const char *func, const char *assertion)
  19                 __attribute__((noreturn));
  20
  21 /*
  22  * Internal assertion (to detect logic errors on which the library user
  23  * has no influence). Use BT_ASSERT_PRE*() or BT_ASSERT_POST*() to check
  24  * preconditions or postconditions which must be directly or indirectly
  25  * satisfied by the library user.
  26  *
  27  * BT_ASSERT() is enabled in both debug and non-debug modes.
  28  */
  29 #define BT_ASSERT(_cond)                                                       \
  30         do {                                                                   \
  31                 if (!(_cond)) {                                                \
  32                         bt_common_assert_failed(__FILE__, __LINE__, __func__,  \
  33                                 G_STRINGIFY(_cond));                           \
  34                 }                                                              \
  35         } while (0)
  36
  37 /*
  38  * Marks a function as being only used within a BT_ASSERT() context.
  39  */
  40 #define BT_ASSERT_FUNC
  41
  42 #ifdef BT_DEBUG_MODE
  43
  44 /*
  45  * Debug mode internal assertion.
  46  */
  47 #define BT_ASSERT_DBG(_cond)    BT_ASSERT(_cond)
  48
  49 /*
  50  * Marks a function as being only used within a BT_ASSERT_DBG() context.
  51  */
  52 #define BT_ASSERT_DBG_FUNC
  53
  54 #else /* BT_DEBUG_MODE */
  55
  56 /*
  57  * When `BT_DEBUG_MODE` is _not_ defined, define BT_ASSERT_DBG() macro
  58  * to the following to trick the compiler into thinking that the
  59  * variable passed as condition to the assertion is used. This is to
  60  * prevent set-but-not-used warnings from the compiler when assertions
  61  * are disabled. The sizeof() operator also makes sure that the `_cond`
  62  * expression is not evaluated, thus preventing unwanted side effects.
  63  *
  64  * In-depth explanation:
  65  * https://stackoverflow.com/questions/37411809/how-to-elegantly-fix-this-unused-variable-warning/37412551#37412551
  66  */
  67 # define BT_ASSERT_DBG(_cond)   ((void) sizeof((void) (_cond), 0))
  68 # define BT_ASSERT_DBG_FUNC     __attribute__((unused))
  69
  70 #endif /* BT_DEBUG_MODE */
  71
  72 #endif /* BABELTRACE_ASSERT_INTERNAL_H */