diff options
| 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/attr/constexpr.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/attr/constexpr.h')
| -rw-r--r-- | include/ruby/3/attr/constexpr.h | 24 |
1 files changed, 9 insertions, 15 deletions
diff --git a/include/ruby/3/attr/constexpr.h b/include/ruby/3/attr/constexpr.h index 11842d87c0..582d9fd000 100644 --- a/include/ruby/3/attr/constexpr.h +++ b/include/ruby/3/attr/constexpr.h @@ -1,4 +1,6 @@ -/** \noop-*-C++-*-vi:ft=cpp +#ifndef RUBY3_ATTR_CONSTEXPR_H /*-*-C++-*-vi:se ft=cpp:*/ +#define RUBY3_ATTR_CONSTEXPR_H +/** * @file * @author Ruby developers <ruby-core@ruby-lang.org> * @copyright This file is a part of the programming language Ruby. @@ -21,11 +23,8 @@ #include "ruby/3/has/feature.h" #include "ruby/3/compiler_is.h" -/** @cond INTERNAL_MACRO*/ -#if defined(RUBY3_ATTR_CONSTEXPR) -# /* Take that. */ - -#elif ! defined(__cplusplus) +/** @cond INTERNAL_MACRO */ +#if ! defined(__cplusplus) # /* Makes no sense. */ # define RUBY3_HAS_ATTR_CONSTEXPR_CXX11 0 # define RUBY3_HAS_ATTR_CONSTEXPR_CXX14 0 @@ -63,10 +62,7 @@ /** @endcond */ /** Wraps (or simulates) C++11 `constexpr`. */ -#if defined(RUBY3_ATTR_CONSTEXPR) -# /* Take that. */ - -#elif RUBY3_HAS_ATTR_CONSTEXPR_CXX14 +#if RUBY3_HAS_ATTR_CONSTEXPR_CXX14 # define RUBY3_ATTR_CONSTEXPR(_) constexpr #elif RUBY3_HAS_ATTR_CONSTEXPR_CXX11 @@ -79,12 +75,10 @@ #endif /** Enables #RUBY3_ATTR_CONSTEXPR iff. #RUBY_NDEBUG. */ -#if defined(RUBY3_ATTR_CONSTEXPR_ON_NDEBUG) -# /* Take that. */ - -#elif RUBY_NDEBUG +#if RUBY_NDEBUG # define RUBY3_ATTR_CONSTEXPR_ON_NDEBUG(_) RUBY3_ATTR_CONSTEXPR(_) - #else # define RUBY3_ATTR_CONSTEXPR_ON_NDEBUG(_) /* void */ #endif + +#endif /* RUBY3_ATTR_CONSTEXPR_H */ |