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ruby--ruby/include/ruby/backward/rubyio.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

18 lines
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C++

#ifndef RUBY_BACKWARD_RUBYIO_H /*-*-C++-*-vi:se ft=cpp:*/
#define RUBY_BACKWARD_RUBYIO_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.
*/
#if defined __GNUC__
#warning use "ruby/io.h" instead of "rubyio.h"
#elif defined _MSC_VER
#pragma message("warning: use \"ruby/io.h\" instead of \"rubyio.h\"")
#endif
#include "ruby/io.h"
#endif /* RUBY_BACKWARD_RUBYIO_H */