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1/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */2#ifndef _LINUX_STDDEF_H3#define _LINUX_STDDEF_H4 5 6 7#ifndef __always_inline8#define __always_inline __inline__9#endif10 11/**12 * __struct_group() - Create a mirrored named and anonyomous struct13 *14 * @TAG: The tag name for the named sub-struct (usually empty)15 * @NAME: The identifier name of the mirrored sub-struct16 * @ATTRS: Any struct attributes (usually empty)17 * @MEMBERS: The member declarations for the mirrored structs18 *19 * Used to create an anonymous union of two structs with identical layout20 * and size: one anonymous and one named. The former's members can be used21 * normally without sub-struct naming, and the latter can be used to22 * reason about the start, end, and size of the group of struct members.23 * The named struct can also be explicitly tagged for layer reuse, as well24 * as both having struct attributes appended.25 */26#define __struct_group(TAG, NAME, ATTRS, MEMBERS...) \27 union { \28 struct { MEMBERS } ATTRS; \29 struct TAG { MEMBERS } ATTRS NAME; \30 }31 32/**33 * __DECLARE_FLEX_ARRAY() - Declare a flexible array usable in a union34 *35 * @TYPE: The type of each flexible array element36 * @NAME: The name of the flexible array member37 *38 * In order to have a flexible array member in a union or alone in a39 * struct, it needs to be wrapped in an anonymous struct with at least 140 * named member, but that member can be empty.41 */42#define __DECLARE_FLEX_ARRAY(TYPE, NAME) \43 struct { \44 struct { } __empty_ ## NAME; \45 TYPE NAME[]; \46 }47#endif48