在OS X 10.10上，gem install therubyracer -v 0.11.4失败
按照这里的步骤“gem install therubyracer -v’0.10’”在osx mavericks上没有安装 ，我能够得到therubyracer -v 0.10.2和0.12.0来安装好，但不是0.11.4。
gem install therubyracer -v 0.11.4
返回：
Building native extensions. This could take a while... ERROR: Error installing therubyracer: ERROR: Failed to build gem native extension. /Users/thooper/.rbenv/versions/2.1.2/bin/ruby -r ./siteconf20150102-7132-9ct9a4.rb extconf.rb creating Makefile Compiling v8 for x64 Using python 2.7.9 Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1 Unable to find a compiler officially supported by v8. It is recommended to use GCC v4.4 or higher Using compiler: g++ Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1 Unable to find a compiler officially supported by v8. It is recommended to use GCC v4.4 or higher ../src/cached-powers.cc:136:18: error: unused variable 'kCachedPowersLength' [-Werror,-Wunused-const-variable] static const int kCachedPowersLength = ARRAY_SIZE(kCachedPowers); ^ 1 error generated. make[1]: *** [/Users/thooper/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/libv8-3.11.8.17/vendor/v8/out/x64.release/obj.target/preparser_lib/src/cached-powers.o] Error 1 make: *** [x64.release] Error 2 /Users/thooper/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/libv8-3.11.8.17/ext/libv8/location.rb:36:in `block in verify_installation!': libv8 did not install properly, expected binary v8 archive '/Users/thooper/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/libv8-3.11.8.17/vendor/v8/out/x64.release/obj.target/tools/gyp/libv8_base.a'to exist, but it was not found (Libv8::Location::Vendor::ArchiveNotFound) from /Users/thooper/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/libv8-3.11.8.17/ext/libv8/location.rb:35:in `each' from /Users/thooper/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/libv8-3.11.8.17/ext/libv8/location.rb:35:in `verify_installation!' from /Users/thooper/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/libv8-3.11.8.17/ext/libv8/location.rb:26:in `install!' from extconf.rb:7:in `' GYP_GENERATORS=make \ build/gyp/gyp --generator-output="out" build/all.gyp \ -Ibuild/standalone.gypi --depth=. \ -Dv8_target_arch=x64 \ -S.x64 -Dv8_can_use_vfp_instructions=true CXX(target) /Users/thooper/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/libv8-3.11.8.17/vendor/v8/out/x64.release/obj.target/preparser_lib/src/allocation.o CXX(target) /Users/thooper/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/libv8-3.11.8.17/vendor/v8/out/x64.release/obj.target/preparser_lib/src/atomicops_internals_x86_gcc.o CXX(target) /Users/thooper/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/libv8-3.11.8.17/vendor/v8/out/x64.release/obj.target/preparser_lib/src/bignum.o CXX(target) /Users/thooper/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/libv8-3.11.8.17/vendor/v8/out/x64.release/obj.target/preparser_lib/src/bignum-dtoa.o CXX(target) /Users/thooper/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/libv8-3.11.8.17/vendor/v8/out/x64.release/obj.target/preparser_lib/src/cached-powers.o extconf failed, exit code 1 Gem files will remain installed in /Users/thooper/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/libv8-3.11.8.17 for inspection. Results logged to /Users/thooper/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/extensions/x86_64-darwin-14/2.1.0-static/libv8-3.11.8.17/gem_make.out
我终于得到了therubyracer 0.11.4来安装和使用Xcode 6.1.1,6.2 beta或6.3 beta（我已经测试了所有3个）以及Xcode 4.6.3（可从以下url获取： https ： //developer.apple.com/ downloads / index.action ）然后运行：
# rename your current version of Xcode to make it distinguishable sudo mv /Applications/Xcode.app /Applications/$(xcodebuild -version | head -1 | sed -e 's/ //').app # Download and install Xcode 4.6.3 and run: sudo mv /Applications/Xcode.app /Applications/Xcode4.6.3.app # Switch to your 4.6.3 version of Xcode sudo xcode-select --switch /Applications/Xcode4.6.3.app # Install the version of libv8 that's tied to your version of TRR: gem install libv8 -v '3.11.8.17' # Switch back to you original version of Xcode sudo xcode-select --switch /Applications/Xcode6.x.app # Install TRR gem install therubyracer -v '0.11.4'
这正是我遇到的问题，我用homebrew-versions解决了它。
问题
我在安装gem libv8时遇到了麻烦。 为了解决这个问题，我通过brew在我的系统上安装了v8，然后使用了选项--with-system-v8 。
$ brew install v8 $ gem install libv8 -v '3.11.8.13' -- --with-system-v8 $ gem install therubyracer -v '0.11.4'
安装gemlibv8没有问题，但最后一行导致原始问题的错误。 然后我试过，
$ gem install therubyracer -v '0.11.4' -- --with-system-v8 --with-v8-dir=/usr/local/Cellar/v8/3.30.33.16
把它指向brew提供的v8。 在这种情况下，错误发生了变化，现在告诉我，我没有提供与3.11.8.13兼容的v8版本。
对于那些谷歌搜索错误消息：
Building native extensions with: '--with-v8-dir=/usr/local/Cellar/v8/3.30.33.16/' This could take a while... ERROR: Error installing therubyracer: ERROR: Failed to build gem native extension. /Users/zeigfreid/.rvm/rubies/ruby-1.9.3-p194/bin/ruby extconf.rb --with-v8-dir=/usr/local/Cellar/v8/3.30.33.16/ checking for main() in -lpthread... yes checking for main() in -lobjc... yes checking for v8.h... no *** 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 --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=/Users/zeigfreid/.rvm/rubies/ruby-1.9.3-p194/bin/ruby --with-pthreadlib --without-pthreadlib --with-objclib --without-objclib --enable-debug --disable-debug --with-v8-dir --with-v8-include --without-v8-include=${v8-dir}/include --with-v8-lib --without-v8-lib=${v8-dir}/lib /Users/zeigfreid/.rvm/gems/ruby-1.9.3-p194@va_rails_3.2.11/gems/libv8-3.11.8.13/ext/libv8/location.rb:50:in `configure': You have chosen to use the version of V8 found on your system (Libv8::Location::System::NotFoundError) and *not* the one that is bundle with the libv8 rubygem. However, it could not be located. please make sure you have a version of v8 that is compatible with 3.11.8.13 installed. You may need to special --with-v8-dir options if it is in a non-standard location thanks, The Mgmt from /Users/zeigfreid/.rvm/gems/ruby-1.9.3-p194@va_rails_3.2.11/gems/libv8-3.11.8.13/lib/libv8.rb:7:in `configure_makefile' from extconf.rb:32:in `' extconf failed, exit code 1 Gem files will remain installed in /Users/zeigfreid/.rvm/gems/ruby-1.9.3-p194@va_rails_3.2.11/gems/therubyracer-0.11.4 for inspection. Results logged to /Users/zeigfreid/.rvm/gems/ruby-1.9.3-p194@va_rails_3.2.11/extensions/x86_64-darwin-13/1.9.1/therubyracer-0.11.4/gem_make.out
解
我决定尝试安装早期版本的v8。 再次使用brew，
$ brew search v8 homebrew/versions/v8-315 v8 $ brew install v8-315 $ brew info v8-315 $ gem install therubyracer -v '0.11.4' -- --with-system-v8 --with-v8-dir=/usr/local/Cellar/v8-315/3.15.11
这很有效。 我最终安装的v8版本是~3.15，但这与3.11.8兼容
这里真正的解决方案是将所有内容更新到最新版本，我不主张使用旧的和过时的gem。 保持系统清洁和最新，即使它很痛！
此行在您的错误消息中出现几次：
It is recommended to use GCC v4.4 or higher
你采取的步骤的链接说运行brew install apple-gcc42 ，可能安装了GCC 4.2。 4.2小于4.4。
C源生成的具体错误似乎是：
../src/cached-powers.cc:136:18: error: unused variable 'kCachedPowersLength' [-Werror,-Wunused-const-variable]
因此，如果您可以以某种方式编辑makefile（或extconf.rb）以删除这些标志，那么这也可能有效。 但是我建议安装一个兼容的编译器，因为修改cflags似乎有点hacky。