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/** \noop-*-C++-*-vi:ft=cpp
* @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.
* @warning Symbols prefixed with either `RUBY3` or `ruby3` 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 #RUBY3_ASSUME / #RUBY3_UNREACHABLE.
*
* These macros must be defined at once because:
*
* - #RUBY3_ASSUME could fallback to #RUBY3_UNREACHABLE.
* - #RUBY3_UNREACHABLE could fallback to #RUBY3_ASSUME.
*/
#ifndef RUBY3_ASSUME_H
#define RUBY3_ASSUME_H
#include "ruby/3/config.h"
#include "ruby/3/cast.h"
#include "ruby/3/has/builtin.h"
/** @cond INTERNAL_MACRO */
#if RUBY3_COMPILER_SINCE(MSVC, 13, 10, 0)
# define RUBY3_HAVE___ASSUME
#elif RUBY3_COMPILER_SINCE(Intel, 13, 0, 0)
# define RUBY3_HAVE___ASSUME
#endif
/** @endcond */
/** Wraps (or simulates) `__builtin_unreachable`. */
#if RUBY3_HAS_BUILTIN(__builtin_unreachable)
# define RUBY3_UNREACHABLE_RETURN(_) __builtin_unreachable()
#elif defined(RUBY3_HAVE___ASSUME)
# define RUBY3_UNREACHABLE_RETURN(_) return (__assume(0), (_))
#else
# define RUBY3_UNREACHABLE_RETURN(_) return (_)
#endif
/** Wraps (or simulates) `__builtin_unreachable`. */
#if RUBY3_HAS_BUILTIN(__builtin_unreachable)
# define RUBY3_UNREACHABLE __builtin_unreachable
#elif defined(RUBY3_HAVE___ASSUME)
# define RUBY3_UNREACHABLE() __assume(0)
#endif
/** Wraps (or simulates) `__asume`. */
#if defined(RUBY3_HAVE___ASSUME)
# define RUBY3_ASSUME __assume
#elif RUBY3_HAS_BUILTIN(__builtin_assume)
# define RUBY3_ASSUME __builtin_assume
#elif ! defined(RUBY3_UNREACHABLE)
# define RUBY3_ASSUME(_) RUBY3_CAST((void)(_))
#else
# define RUBY3_ASSUME(_) \
(RB_LIKELY(!!(_)) ? RUBY3_CAST((void)0) : RUBY3_UNREACHABLE())
#endif
#if ! defined(RUBY3_UNREACHABLE)
# define RUBY3_UNREACHABLE() RUBY3_ASSUME(0)
#endif
#endif /* RUBY3_ASSUME_H */
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