安装 ffi 时出错。无法构建本机扩展

Question

我在终端机里有这个注释。

Building native extensions.  This could take a while...
ERROR:  Error installing ffi:
  ERROR: Failed to build gem native extension.

/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby -r ./siteconf20150919-3961-k5bsnl.rb extconf.rb
checking for ffi.h... *** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Provided configuration options:
  --with-opt-dir
  --without-opt-dir
  --with-opt-include
  --without-opt-include=${opt-dir}/include
  --with-opt-lib
  --without-opt-lib=${opt-dir}/lib
  --with-make-prog
  --without-make-prog
  --srcdir=.
  --curdir
  --ruby=/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby
  --with-ffi_c-dir
  --without-ffi_c-dir
  --with-ffi_c-include
  --without-ffi_c-include=${ffi_c-dir}/include
  --with-ffi_c-lib
  --without-ffi_c-lib=${ffi_c-dir}/
  --with-libffi-config
  --without-libffi-config
  --with-pkg-config
  --without-pkg-config
/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:434:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.
  from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:549:in `block in try_compile'
  from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:502:in `with_werror'
  from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:549:in `try_compile'
  from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:1044:in `block in have_header'
  from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:895:in `block in checking_for'
  from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:340:in `block (2 levels) in postpone'
  from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:310:in `open'
  from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:340:in `block in postpone'
  from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:310:in `open'
  from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:336:in `postpone'
  from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:894:in `checking_for'
  from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:1043:in `have_header'
  from extconf.rb:16:in `<main>'

extconf failed, exit code 1

Gem files will remain installed in /Library/Ruby/Gems/2.0.0/gems/ffi-1.9.6 for inspection.
Results logged to /Library/Ruby/Gems/2.0.0/extensions/universal-darwin-14/2.0.0/ffi-1.9.6/gem_make.out

Answer 1

报错信息中有这一行：

You have to install development tools first.

请确保您已安装 XCode 和 Xcode Command Line Tools。请至少打开 XCode 一次以接受许可协议。

Answer 2

如果你有 brew，我建议你在命令行中输入 ffi 库

brew install libffi

之后尝试安装你 gem

gem install ffi

安装 ffi 时出错。无法构建本机扩展

Error installing ffi. Faild to build native Extention

ruby

macos

rubygems

ruby-on-rails

ffi