Change required clang-format version to 14

[babeltrace.git] / src / common / macros.h

diff --git a/src/common/macros.h b/src/common/macros.h
index 23d4b310d573ab49c0f001d900fef04cf678b307..34ac393f76bda366a8ad142ff4d568ba3465bb25 100644 (file)
--- a/src/common/macros.h
+++ b/src/common/macros.h
@@ -1,28 +1,21 @@
-#ifndef _BABELTRACE_INTERNAL_H
-#define _BABELTRACE_INTERNAL_H
-
 /*
- * Copyright 2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * SPDX-License-Identifier: MIT
  *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
- * SOFTWARE.
+ * Copyright 2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  */
 
+#ifndef _BABELTRACE_INTERNAL_H
+#define _BABELTRACE_INTERNAL_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef __cplusplus
+#define BT_EXTERN_C extern "C"
+#else
+#define BT_EXTERN_C
+#endif
 
 #define bt_max_t(type, a, b)   \
        ((type) (a) > (type) (b) ? (type) (a) : (type) (b))
@@ -38,4 +31,58 @@
 #define BT_HIDDEN __attribute__((visibility("hidden")))
 #endif
 
+/*
+ * Yield `ref`'s value while setting `ref` to NULL.
+ *
+ * This can be used to give a strong reference to a callee:
+ *
+ *   add_foo_to_list(list, BT_MOVE_REF(foo));
+ *
+ * or in a simple assignment:
+ *
+ *   my_struct->foo = BT_MOVE_REF(foo);
+ *
+ * When moving a reference in a function call, the reference is given to the
+ * callee even if that function call fails, so make sure the called function
+ * is written accordingly.
+ */
+
+#define BT_MOVE_REF(ref)               \
+       ({                              \
+               __typeof__(ref) _ref = ref;     \
+               ref = NULL;             \
+               _ref;                   \
+       })
+
+/*
+ * Copied from:
+ * <https://stackoverflow.com/questions/37411809/how-to-elegantly-fix-this-unused-variable-warning/37412551#37412551>:
+ *
+ * * sizeof() ensures that the expression is not evaluated at all, so
+ *   its side-effects don't happen. That is to be consistent with the
+ *   usual behaviour of debug-only constructs, such as assert().
+ *
+ * * `((_expr), 0)` uses the comma operator to swallow the actual type
+ *   of `(_expr)`. This is to prevent VLAs from triggering evaluation.
+ *
+ * * `(void)` explicitly ignores the result of `(_expr)` and sizeof() so
+ *   no "unused value" warning appears.
+ */
+
+#define BT_USE_EXPR(_expr)             ((void) sizeof((void) (_expr), 0))
+#define BT_USE_EXPR2(_expr1, _expr2)                                   \
+       ((void) sizeof((void) (_expr1), (void) (_expr2), 0))
+#define BT_USE_EXPR3(_expr1, _expr2, _expr3)                           \
+       ((void) sizeof((void) (_expr1), (void) (_expr2), (void) (_expr3), 0))
+#define BT_USE_EXPR4(_expr1, _expr2, _expr3, _expr4)                   \
+       ((void) sizeof((void) (_expr1), (void) (_expr2),                \
+               (void) (_expr3), (void) (_expr4), 0))
+#define BT_USE_EXPR5(_expr1, _expr2, _expr3, _expr4, _expr5)           \
+       ((void) sizeof((void) (_expr1), (void) (_expr2),                \
+               (void) (_expr3), (void) (_expr4), (void) (_expr5), 0))
+
+#ifdef __cplusplus
+}
+#endif
+
 #endif