#ifndef RBIMPL_ATTR_NOEXCEPT_H /*-*-C++-*-vi:se ft=cpp:*/

#define RBIMPL_ATTR_NOEXCEPT_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.

* @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_NOEXCEPT.

*

* This isn't actually an attribute in C++ but who cares...

*

* Mainly due to aesthetic reasons, this one is rarely used in the project.

* But can be handy on occasions, especially when a function's noexcept-ness

* depends on its calling functions.

*

* ### Q&A ###

*

* - Q: Can a function that raises Ruby exceptions be attributed `noexcept`?

*

* - A: Yes. `noexcept` is about C++ exceptions, not Ruby's. They don't

* interface each other. You can safely attribute a function that raises

* Ruby exceptions as `noexcept`.

*

* - Q: How, then, can I assert that a function I wrote doesn't raise any Ruby

* exceptions?

*

* - A: `__attribute__((__leaf__))` is for that purpose. A function attributed

* as leaf can still throw C++ exceptions, but not Ruby's. Note however,

* that it's extremely difficult -- if not impossible -- to assert that a

* function doesn't raise any Ruby exceptions at all. Use of that

* attribute is not recommended; mere mortals can't properly use that by

* hand.

*

* - Q: Does it make sense to attribute an inline function `noexcept`?

*

* - A: I thought so before. But no, I don't think they are useful any longer.

*

* - When an inline function attributed `noexcept` actually doesn't throw

* any exceptions at all: these days I don't see any difference in

* generated assembly by adding/removing this attribute. C++ compilers

* get smarter and smarter. Today they can infer if it actually throws

* or not without any annotations by humans (correct me if I'm wrong).

*

* - When an inline function attributed `noexcept` actually _does_ throw an

* exception: they have to call `std::terminate` then (C++ standard

* mandates so). This means exception handling routines are actually

* enforced, not omitted. This doesn't impact runtime performance (The

* Itanium C++ ABI has zero-cost exception handling), but does impact on

* generated binary size. This is bad.

*/

#include "ruby/internal/compiler_since.h"

#include "ruby/internal/has/feature.h"

/** Wraps (or simulates) C++11 `noexcept` */

#if ! defined(__cplusplus)

# /* Doesn't make sense. */

# define RBIMPL_ATTR_NOEXCEPT(_) /* void */

#elif RBIMPL_HAS_FEATURE(cxx_noexcept)

# define RBIMPL_ATTR_NOEXCEPT(_) noexcept(noexcept(_))

#elif defined(__GXX_EXPERIMENTAL_CXX0X__) && __GXX_EXPERIMENTAL_CXX0X__

# define RBIMPL_ATTR_NOEXCEPT(_) noexcept(noexcept(_))

#elif defined(__INTEL_CXX11_MODE__)

# define RBIMPL_ATTR_NOEXCEPT(_) noexcept(noexcept(_))

#elif RBIMPL_COMPILER_SINCE(MSVC, 19, 0, 0)

# define RBIMPL_ATTR_NOEXCEPT(_) noexcept(noexcept(_))

#elif __cplusplus >= 201103L

# define RBIMPL_ATTR_NOEXCEPT(_) noexcept(noexcept(_))

#else

# define RBIMPL_ATTR_NOEXCEPT(_) /* void */

#endif

#endif /* RBIMPL_ATTR_NOEXCEPT_H */