X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=include%2Flttng%2Fust-compiler.h;h=dcc72594858060a7a32aec36fb9a2cc19e89dfa0;hb=c0c0989ab70574e09b2f7e8b48c2da6af664a849;hp=c289628580ee420346a24e6e72bc9f7fa9299ebd;hpb=e1904921db97b70d94e69f0ab3264c6f7fe62f32;p=lttng-ust.git

diff --git a/include/lttng/ust-compiler.h b/include/lttng/ust-compiler.h
index c2896285..dcc72594 100644
--- a/include/lttng/ust-compiler.h
+++ b/include/lttng/ust-compiler.h
@@ -1,29 +1,15 @@
-#ifndef _LTTNG_UST_COMPILER_H
-#define _LTTNG_UST_COMPILER_H
-
 /*
- * Copyright 2011-2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *                       Paul Woegerer <paul_woegerer@mentor.com>
- *
- * 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.
+ * SPDX-License-Identifier: MIT
  *
- * 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 (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * Copyright (C) 2011-2012 Paul Woegerer <paul_woegerer@mentor.com>
  */
 
+#ifndef _LTTNG_UST_COMPILER_H
+#define _LTTNG_UST_COMPILER_H
+
+#include <assert.h>
+
 #define lttng_ust_notrace __attribute__((no_instrument_function))
 #define LTTNG_PACKED	__attribute__((__packed__))
 
@@ -71,4 +57,31 @@
 #define __LTTNG_COMPOUND_LITERAL(type, ...)	(type[]) { __VA_ARGS__ }
 #endif
 
+/*
+ * Compile time assertion.
+ * - predicate: boolean expression to evaluate,
+ * - msg: string to print to the user on failure when `static_assert()` is
+ *   supported,
+ * - c_identifier_msg: message to be included in the typedef to emulate a
+ *   static assertion. This parameter must be a valid C identifier as it will
+ *   be used as a typedef name.
+ */
+#if defined (__cplusplus) || __STDC_VERSION__ >= 201112L
+#define lttng_static_assert(predicate, msg, c_identifier_msg)  \
+	static_assert(predicate, msg)
+#else
+/*
+ * Evaluates the predicate and emit a compilation error on failure.
+ *
+ * If the predicate evaluates to true, this macro emits a typedef of an array
+ * of size 0.
+ *
+ * If the predicate evaluates to false, this macro emits a typedef of an array
+ * of negative size which is invalid in C and forces a compiler error. The msg
+ * parameter is used in the tentative typedef so it is printed to the user.
+ */
+#define lttng_static_assert(predicate, msg, c_identifier_msg)  \
+    typedef char lttng_static_assert_##c_identifier_msg[2*!!(predicate)-1];
+#endif
+
 #endif /* _LTTNG_UST_COMPILER_H */