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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 /missing | |
| 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 'missing')
| -rw-r--r-- | missing/crypt.h | 5 | ||||
| -rw-r--r-- | missing/file.h | 3 |
2 files changed, 3 insertions, 5 deletions
diff --git a/missing/crypt.h b/missing/crypt.h index 7c2642f593..ff135eee93 100644 --- a/missing/crypt.h +++ b/missing/crypt.h @@ -1,3 +1,5 @@ +#ifndef CRYPT_H +#define CRYPT_H 1 /* * Copyright (c) 1989, 1993 * The Regents of the University of California. All rights reserved. @@ -30,9 +32,6 @@ * SUCH DAMAGE. */ -#ifndef CRYPT_H -#define CRYPT_H 1 - /* ===== Configuration ==================== */ #ifdef CHAR_BITS diff --git a/missing/file.h b/missing/file.h index 241d716563..5e25c4761c 100644 --- a/missing/file.h +++ b/missing/file.h @@ -1,7 +1,6 @@ -/* This is file FILE.H */ - #ifndef _FILE_H_ #define _FILE_H_ +/* This is file FILE.H */ #include <fcntl.h> |