X-Git-Url: http://git.efficios.com/?a=blobdiff_plain;f=src%2Fcommon%2Fmacros.h;h=718a3050ccb1b4b96b9a00cf84adeb35185bdae0;hb=1778c2a4134647150b199b2b57130817144446b0;hp=036b3e012b7fc47b360f63007501d5eea20ffe7d;hpb=55b71f05674d8c77a4f39709784707ddabe6177b;p=babeltrace.git

diff --git a/src/common/macros.h b/src/common/macros.h
index 036b3e01..718a3050 100644
--- a/src/common/macros.h
+++ b/src/common/macros.h
@@ -1,28 +1,11 @@
-#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
 
 #define bt_max_t(type, a, b)	\
 	((type) (a) > (type) (b) ? (type) (a) : (type) (b))
@@ -56,9 +39,36 @@
 
 #define BT_MOVE_REF(ref) 		\
 	({				\
-		__auto_type _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))
+
 #endif