From 4ff3f205408ff8bb413d69151105d301858136ba Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=E5=8D=9C=E9=83=A8=E6=98=8C=E5=B9=B3?= Date: Fri, 10 Apr 2020 14:11:40 +0900 Subject: 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 --- vm_debug.h | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'vm_debug.h') diff --git a/vm_debug.h b/vm_debug.h index 8e0350d147..93ee2e4297 100644 --- a/vm_debug.h +++ b/vm_debug.h @@ -1,3 +1,5 @@ +#ifndef RUBY_DEBUG_H +#define RUBY_DEBUG_H /********************************************************************** vm_debug.h - YARV Debug function interface @@ -9,9 +11,6 @@ **********************************************************************/ -#ifndef RUBY_DEBUG_H -#define RUBY_DEBUG_H - #include "ruby/ruby.h" #include "node.h" -- cgit v1.2.1