Revert "compiler.h: Introduce caa_unqual_scalar_typeof"

[userspace-rcu.git] / include / urcu / compiler.h

diff --git a/include/urcu/compiler.h b/include/urcu/compiler.h
index 827ec1fd6eee0d00d5e863f9268fa89b7ae2d59e..0de713adc1a03f4affc48eda0efd03c1b7c1a470 100644 (file)
--- a/include/urcu/compiler.h
+++ b/include/urcu/compiler.h
@@ -74,6 +74,23 @@
                (type *)((char *)__ptr - offsetof(type, member));       \
        })
 
+/*
+ * caa_container_of_check_null - Get the address of an object containing a field.
+ *
+ * @ptr: pointer to the field.
+ * @type: type of the object.
+ * @member: name of the field within the object.
+ *
+ * Return the address of the object containing the field. Return NULL if
+ * @ptr is NULL.
+ */
+#define caa_container_of_check_null(ptr, type, member)                 \
+       __extension__                                                   \
+       ({                                                              \
+               const __typeof__(((type *) NULL)->member) * __ptr = (ptr); \
+               (__ptr) ? (type *)((char *)__ptr - offsetof(type, member)) : NULL; \
+       })
+
 #define CAA_BUILD_BUG_ON_ZERO(cond) (sizeof(struct { int:-!!(cond); }))
 #define CAA_BUILD_BUG_ON(cond) ((void)CAA_BUILD_BUG_ON_ZERO(cond))
 
@@ -123,30 +140,4 @@
                                + __GNUC_PATCHLEVEL__)
 #endif
 
-#ifdef __cplusplus
-#define caa_unqual_scalar_typeof(x)                                    \
-       std::remove_cv<std::remove_reference<decltype(x)>::type>::type
-#else
-#define caa_scalar_type_to_expr(type)                                  \
-       unsigned type: (unsigned type)0,                                \
-       signed type: (signed type)0
-
-/*
- * Use C11 _Generic to express unqualified type from expression. This removes
- * volatile qualifier from expression type.
- */
-#define caa_unqual_scalar_typeof(x)                                    \
-       __typeof__(                                                     \
-               _Generic((x),                                           \
-                       char: (char)0,                                  \
-                       caa_scalar_type_to_expr(char),                  \
-                       caa_scalar_type_to_expr(short),         \
-                       caa_scalar_type_to_expr(int),                   \
-                       caa_scalar_type_to_expr(long),                  \
-                       caa_scalar_type_to_expr(long long),             \
-                       default: (x)                                    \
-               )                                                       \
-       )
-#endif
-
 #endif /* _URCU_COMPILER_H */