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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 /transcode_data.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 'transcode_data.h')
| -rw-r--r-- | transcode_data.h | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/transcode_data.h b/transcode_data.h index 2007eb06d3..9455ec93c9 100644 --- a/transcode_data.h +++ b/transcode_data.h @@ -1,3 +1,5 @@ +#ifndef RUBY_TRANSCODE_DATA_H +#define RUBY_TRANSCODE_DATA_H 1 /********************************************************************** transcode_data.h - @@ -11,9 +13,6 @@ #include "ruby/ruby.h" -#ifndef RUBY_TRANSCODE_DATA_H -#define RUBY_TRANSCODE_DATA_H 1 - RUBY_SYMBOL_EXPORT_BEGIN #define WORDINDEX_SHIFT_BITS 2 |