src/common/macros.h

   1 /*
   2  * SPDX-License-Identifier: MIT
   3  *
   4  * Copyright 2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  */
   6
   7 #ifndef _BABELTRACE_INTERNAL_H
   8 #define _BABELTRACE_INTERNAL_H
   9
  10 #ifdef __cplusplus
  11 extern "C" {
  12 #endif
  13
  14 #ifdef __cplusplus
  15 #define BT_EXTERN_C extern "C"
  16 #else
  17 #define BT_EXTERN_C
  18 #endif
  19
  20 #define bt_max_t(type, a, b)    \
  21         ((type) (a) > (type) (b) ? (type) (a) : (type) (b))
  22
  23 /*
  24  * BT_EXPORT: set the visibility for exported functions.
  25  */
  26 #if defined(_WIN32) || defined(__CYGWIN__)
  27 #define BT_EXPORT
  28 #else
  29 #define BT_EXPORT __attribute__((visibility("default")))
  30 #endif
  31
  32 /*
  33  * BT_NOEXCEPT: defined to `noexcept` if compiling as C++, else empty.
  34  */
  35 #if defined(__cplusplus)
  36 #define BT_NOEXCEPT noexcept
  37 #else
  38 #define BT_NOEXCEPT
  39 #endif
  40
  41 /* Enable `txt` if developer mode is enabled. */
  42 #ifdef BT_DEV_MODE
  43 #define BT_IF_DEV_MODE(txt) txt
  44 #else
  45 #define BT_IF_DEV_MODE(txt)
  46 #endif
  47
  48 /* Wrapper for g_array_index that adds bound checking.  */
  49 #define bt_g_array_index(a, t, i)               \
  50         g_array_index((a), t, ({ BT_ASSERT_DBG((i) < (a)->len); (i); }))
  51
  52 /*
  53  * Copied from:
  54  * <https://stackoverflow.com/questions/37411809/how-to-elegantly-fix-this-unused-variable-warning/37412551#37412551>:
  55  *
  56  * * sizeof() ensures that the expression is not evaluated at all, so
  57  *   its side-effects don't happen. That is to be consistent with the
  58  *   usual behaviour of debug-only constructs, such as assert().
  59  *
  60  * * `((_expr), 0)` uses the comma operator to swallow the actual type
  61  *   of `(_expr)`. This is to prevent VLAs from triggering evaluation.
  62  *
  63  * * `(void)` explicitly ignores the result of `(_expr)` and sizeof() so
  64  *   no "unused value" warning appears.
  65  */
  66
  67 #define BT_USE_EXPR(_expr)              ((void) sizeof((void) (_expr), 0))
  68 #define BT_USE_EXPR2(_expr1, _expr2)                                    \
  69         ((void) sizeof((void) (_expr1), (void) (_expr2), 0))
  70 #define BT_USE_EXPR3(_expr1, _expr2, _expr3)                            \
  71         ((void) sizeof((void) (_expr1), (void) (_expr2), (void) (_expr3), 0))
  72 #define BT_USE_EXPR4(_expr1, _expr2, _expr3, _expr4)                    \
  73         ((void) sizeof((void) (_expr1), (void) (_expr2),                \
  74                 (void) (_expr3), (void) (_expr4), 0))
  75 #define BT_USE_EXPR5(_expr1, _expr2, _expr3, _expr4, _expr5)            \
  76         ((void) sizeof((void) (_expr1), (void) (_expr2),                \
  77                 (void) (_expr3), (void) (_expr4), (void) (_expr5), 0))
  78
  79 #define BT_DIAG_PUSH _Pragma ("GCC diagnostic push")
  80 #define BT_DIAG_POP _Pragma ("GCC diagnostic push")
  81
  82 #define BT_DIAG_IGNORE_SHADOW _Pragma("GCC diagnostic ignored \"-Wshadow\"")
  83
  84 #if defined __clang__
  85 #  if __has_warning("-Wunused-but-set-variable")
  86 #    define BT_DIAG_IGNORE_UNUSED_BUT_SET_VARIABLE \
  87         _Pragma("GCC diagnostic ignored \"-Wunused-but-set-variable\"")
  88 #  endif
  89 #endif
  90
  91 #if !defined BT_DIAG_IGNORE_UNUSED_BUT_SET_VARIABLE
  92 #  define BT_DIAG_IGNORE_UNUSED_BUT_SET_VARIABLE
  93 #endif
  94
  95 #ifdef __cplusplus
  96 }
  97 #endif
  98
  99 #endif