X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=include%2Flttng%2Fust-compiler.h;h=e7d72e0da3fd21843b8caa0879200a4c43c38f21;hb=ab249ecfea7ddc352e1fb5c3b97a4f0fbb62f3ca;hp=31eaf73c0139026b9adbb8c87ca7076c0df77125;hpb=4f74bc5ef1bff1198cf47bd823cc5dc2e8fd9649;p=lttng-ust.git

diff --git a/include/lttng/ust-compiler.h b/include/lttng/ust-compiler.h
index 31eaf73c..e7d72e0d 100644
--- a/include/lttng/ust-compiler.h
+++ b/include/lttng/ust-compiler.h
@@ -24,6 +24,8 @@
  * SOFTWARE.
  */
 
+#include <assert.h>
+
 #define lttng_ust_notrace __attribute__((no_instrument_function))
 #define LTTNG_PACKED	__attribute__((__packed__))
 
@@ -43,4 +45,59 @@
 #  define __lttng_ust_variable_attribute_no_sanitize_address
 #endif
 
+/*
+ * g++ 4.8 and prior do not support C99 compound literals. Therefore,
+ * force allocating those on the heap with these C++ compilers.
+ */
+#if defined (__cplusplus) && defined (__GNUC__) && \
+	(__GNUC__ < 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ <= 8))
+# ifndef LTTNG_ALLOCATE_COMPOUND_LITERAL_ON_HEAP
+#  define LTTNG_ALLOCATE_COMPOUND_LITERAL_ON_HEAP
+# endif
+#endif
+
+/*
+ * Compound literals with static storage are needed by LTTng.
+ * Compound literals are part of the C99 and C11 standards, but not
+ * part of the C++ standards. However, those are supported by both g++ and
+ * clang. In order to be strictly C++11 compliant, defining
+ * LTTNG_ALLOCATE_COMPOUND_LITERAL_ON_HEAP before including this header
+ * allocates those on the heap in C++.
+ *
+ * Example use:
+ * static struct mystruct *var = __LTTNG_COMPOUND_LITERAL(struct mystruct, { 1, 2, 3 });
+ */
+#if defined (__cplusplus) && defined (LTTNG_ALLOCATE_COMPOUND_LITERAL_ON_HEAP)
+#define __LTTNG_COMPOUND_LITERAL(type, ...)	new (type) __VA_ARGS__
+#else
+#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 */