關於mac安裝rails報錯clang: error: unknown argument

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mac上安裝rails的時候報錯，

安裝rails的在終端執行了一句命令：

$sudo gem install rails

報錯了，報錯信息爲

clang: error: unknown argument: '-multiply_definedsuppress' [-Wunused-command-line-argument-hard-error-in-future]

 

完整的執行過程及報錯信息以下：

 

angela@angeladeMacBook-Air:~$sudo gem install rails

Password:

Building native extensions.  This could take a while...

ERROR:  Error installing rails:

ERROR: Failed to build gem native extension.

/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby extconf.rb

creating Makefile

make "DESTDIR="

compiling generator.c

linking shared-object json/ext/generator.bundle

clang: error: unknown argument: '-multiply_definedsuppress' [-Wunused-command-line-argument-hard-error-in-future]

clang: note: this will be a hard error (cannot be downgraded to a warning) in the future

make: *** [generator.bundle] Error 1

Gem files will remain installed in /Library/Ruby/Gems/2.0.0/gems/json-1.8.1 for inspection.

Results logged to /Library/Ruby/Gems/2.0.0/gems/json-1.8.1/ext/json/ext/generator/gem_make.out

 

緣由很簡單，

Xcode 5.1中的蘋果編譯器將不認識的命令行視爲錯誤行爲。這類報錯常出如今ruby和python的安裝過程當中，由於這兩類程序中，不少編譯語句較爲特殊。

 

解決方案就是在安裝語句前面加上這句

ARCHFLAGS=-Wno-error=unused-command-line-argument-hard-error-in-future ，

 

以安裝rails爲例,使用如下的語句：

$ARCHFLAGS=-Wno-error=unused-command-line-argument-hard-error-in-future gem install rails