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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
commit4ff3f205408ff8bb413d69151105d301858136ba (patch)
tree0494fea3f4cdb82ec1d34e462438389dfea8b8da /method.h
parenta3f6f67967644f34226b4424227d2eec52fedd45 (diff)
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
Notes
Notes: Merged: https://github.com/ruby/ruby/pull/3023
Diffstat (limited to 'method.h')
-rw-r--r--method.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/method.h b/method.h
index 01a25d368c..3aa4deb2f8 100644
--- a/method.h
+++ b/method.h
@@ -1,3 +1,5 @@
+#ifndef RUBY_METHOD_H
+#define RUBY_METHOD_H 1
/**********************************************************************
method.h -
@@ -8,8 +10,6 @@
Copyright (C) 2009 Koichi Sasada
**********************************************************************/
-#ifndef RUBY_METHOD_H
-#define RUBY_METHOD_H 1
#include "internal.h"
#include "internal/imemo.h"