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ruby--ruby/include/ruby/internal/attr/maybe_unused.h

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#ifndef RBIMPL_ATTR_MAYBE_UNUSED_H /*-*-C++-*-vi:se ft=cpp:*/
#define RBIMPL_ATTR_MAYBE_UNUSED_H
/**
* @file
* @author Ruby developers <ruby-core@ruby-lang.org>
* @copyright This file is a part of the programming language Ruby.
* Permission is hereby granted, to either redistribute and/or
* modify this file, provided that the conditions mentioned in the
* file COPYING are met. Consult the file for details.
2020-05-04 03:27:48 -04:00
* @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
* implementation details. Don't take them as canon. They could
* rapidly appear then vanish. The name (path) of this header file
* is also an implementation detail. Do not expect it to persist
* at the place it is now. Developers are free to move it anywhere
* anytime at will.
* @note To ruby-core: remember that this header can be possibly
* recursively included from extension libraries written in C++.
* Do not expect for instance `__VA_ARGS__` is always available.
* We assume C99 for ruby itself but we don't assume languages of
* extension libraries. They could be written in C++98.
* @brief Defines #RBIMPL_ATTR_MAYBE_UNUSED.
*/
#include "ruby/internal/has/attribute.h"
#include "ruby/internal/has/c_attribute.h"
#include "ruby/internal/has/cpp_attribute.h"
/** Wraps (or simulates) `[[maybe_unused]]` */
#if RBIMPL_HAS_CPP_ATTRIBUTE(maybe_unused)
# define RBIMPL_ATTR_MAYBE_UNUSED() [[maybe_unused]]
#elif RBIMPL_HAS_C_ATTRIBUTE(maybe_unused)
# define RBIMPL_ATTR_MAYBE_UNUSED() [[maybe_unused]]
#elif RBIMPL_HAS_ATTRIBUTE(unused)
# define RBIMPL_ATTR_MAYBE_UNUSED() __attribute__((__unused__))
#else
# define RBIMPL_ATTR_MAYBE_UNUSED() /* void */
#endif
#endif /* RBIMPL_ATTR_MAYBE_UNUSED */