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| author | 卜部昌平 <shyouhei@ruby-lang.org> | 2020-04-10 14:11:40 +0900 |
|---|---|---|
| committer | 卜部昌平 <shyouhei@ruby-lang.org> | 2020-04-13 16:06:00 +0900 |
| commit | 4ff3f205408ff8bb413d69151105d301858136ba (patch) | |
| tree | 0494fea3f4cdb82ec1d34e462438389dfea8b8da /include/ruby/3/cast.h | |
| parent | a3f6f67967644f34226b4424227d2eec52fedd45 (diff) | |
| download | ruby-4ff3f205408ff8bb413d69151105d301858136ba.tar.gz | |
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
Diffstat (limited to 'include/ruby/3/cast.h')
| -rw-r--r-- | include/ruby/3/cast.h | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/include/ruby/3/cast.h b/include/ruby/3/cast.h index 10caa809e5..7f0dce9010 100644 --- a/include/ruby/3/cast.h +++ b/include/ruby/3/cast.h @@ -1,4 +1,6 @@ -/** \noop-*-C++-*-vi:ft=cpp +#ifndef RUBY3_CAST_H /*-*-C++-*-vi:se ft=cpp:*/ +#define RUBY3_CAST_H +/** * @file * @author Ruby developers <ruby-core@ruby-lang.org> * @copyright This file is a part of the programming language Ruby. @@ -24,10 +26,7 @@ * warnings. Ruby internals are pure C so they should not bother. */ -#if defined(RUBY3_CAST) -# /* Take that. */ - -#elif ! defined(__cplusplus) +#if ! defined(__cplusplus) # define RUBY3_CAST(expr) (expr) #elif RUBY3_COMPILER_SINCE(GCC, 4, 6, 0) @@ -47,3 +46,5 @@ # define RUBY3_CAST(expr) (expr) #endif /** @endcond */ + +#endif /* RUBY3_CAST_H */ |