From: "shyouhei (Shyouhei Urabe)" <shyouhei@...>
Date: 2013-07-25T07:31:41+09:00
Subject: [ruby-dev:47540] [ruby-trunk - Bug #8674] [patch] unused-parameter warning in ruby/ruby.h


Issue #8674 has been updated by shyouhei (Shyouhei Urabe).


Linda_pp (R H) wrote:
> + #else
> +     (void)filename;
> +     (void)line;
>   #endif

(void) で黙らせるのは感心しません。gccにおける警告の抑制が目的なら__attribute__((used))か__attribute__((unused))のどちらか適切な方を使うべきです。基本的に警告を黙らせる目的でキャスト使うのは邪悪です。避けるべきと思います。
----------------------------------------
Bug #8674: [patch] unused-parameter warning in ruby/ruby.h
https://bugs.ruby-lang.org/issues/8674#change-40655

Author: Linda_pp (R H)
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: 
ruby -v: ruby 2.0.0p195 (2013-05-14 revision 40734) [x86_64-darwin12.3.0]
Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN


C++ のプログラムで ruby.h をインクルードすると ruby/ruby.h にて unused-parameter の警告が出ます．

・警告内容
In file included from /Users/rhayasd/.rbenv/versions/2.1.0-dev/include/ruby-2.1.0/ruby.h:33:0,
                 from ruby_interpreter.cpp:6:
/Users/rhayasd/.rbenv/versions/2.1.0-dev/include/ruby-2.1.0/ruby/ruby.h:1270:1: warning: unused parameter 'filename' [-Wunused-parameter]
 rb_obj_wb_unprotect(VALUE x, const char *filename, int line)
 ^
/Users/rhayasd/.rbenv/versions/2.1.0-dev/include/ruby-2.1.0/ruby/ruby.h:1270:1: warning: unused parameter 'line' [-Wunused-parameter]
/Users/rhayasd/.rbenv/versions/2.1.0-dev/include/ruby-2.1.0/ruby/ruby.h:1290:1: warning: unused parameter 'oldv' [-Wunused-parameter]
 rb_obj_written(VALUE a, VALUE oldv, VALUE b, const char *filename, int line)
 ^
/Users/rhayasd/.rbenv/versions/2.1.0-dev/include/ruby-2.1.0/ruby/ruby.h:1290:1: warning: unused parameter 'filename' [-Wunused-parameter]
/Users/rhayasd/.rbenv/versions/2.1.0-dev/include/ruby-2.1.0/ruby/ruby.h:1290:1: warning: unused parameter 'line' [-Wunused-parameter]

・コンパイラ
　gcc 4.8.1

・コマンド
　g++ -Wall -Wextra -std=c++11 source.cpp

・環境
　MacOS X 10.8.4


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