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ruby--ruby/include/ruby/3/compiler_is/msvc.h
卜部昌平 4ff3f20540 add #include guard hack
According to MSVC manual (*1), cl.exe can skip including a header file
when that:

- contains #pragma once, or
- starts with #ifndef, or
- starts with #if ! defined.

GCC has a similar trick (*2), but it acts more stricter (e. g. there
must be _no tokens_ outside of #ifndef...#endif).

Sun C lacked #pragma once for a looong time.  Oracle Developer Studio
12.5 finally implemented it, but we cannot assume such recent version.

This changeset modifies header files so that each of them include
strictly one #ifndef...#endif.  I believe this is the most portable way
to trigger compiler optimizations. [Bug #16770]

*1: https://docs.microsoft.com/en-us/cpp/preprocessor/once
*2: https://gcc.gnu.org/onlinedocs/cppinternals/Guard-Macros.html
2020-04-13 16:06:00 +09:00

57 lines
2.4 KiB
C++

#ifndef RUBY3_COMPILER_IS_MSVC_H /*-*-C++-*-vi:se ft=cpp:*/
#define RUBY3_COMPILER_IS_MSVC_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 `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_COMPILER_IS_MSVC.
*/
#include "ruby/3/compiler_is/clang.h"
#include "ruby/3/compiler_is/intel.h"
#if ! defined(_MSC_VER)
# define RUBY3_COMPILER_IS_MSVC 0
#elif RUBY3_COMPILER_IS(Clang)
# define RUBY3_COMPILER_IS_MSVC 0
#elif RUBY3_COMPILER_IS(Intel)
# define RUBY3_COMPILER_IS_MSVC 0
#elif _MSC_VER >= 1400
# define RUBY3_COMPILER_IS_MSVC 1
# /* _MSC_FULL_VER = XXYYZZZZZ */
# define RUBY3_COMPILER_VERSION_MAJOR (_MSC_FULL_VER / 10000000)
# define RUBY3_COMPILER_VERSION_MINOR (_MSC_FULL_VER % 10000000 / 100000)
# define RUBY3_COMPILER_VERSION_PATCH (_MSC_FULL_VER % 100000)
#elif defined(_MSC_FULL_VER)
# define RUBY3_COMPILER_IS_MSVC 1
# /* _MSC_FULL_VER = XXYYZZZZ */
# define RUBY3_COMPILER_VERSION_MAJOR (_MSC_FULL_VER / 1000000)
# define RUBY3_COMPILER_VERSION_MINOR (_MSC_FULL_VER % 1000000 / 10000)
# define RUBY3_COMPILER_VERSION_PATCH (_MSC_FULL_VER % 10000)
#else
# define RUBY3_COMPILER_IS_MSVC 1
# /* _MSC_VER = XXYY */
# define RUBY3_COMPILER_VERSION_MAJOR (_MSC_VER / 100)
# define RUBY3_COMPILER_VERSION_MINOR (_MSC_VER % 100)
# define RUBY3_COMPILER_VERSION_PATCH 0
#endif
#endif /* RUBY3_COMPILER_IS_MSVC_H */