Ruby Gem install Json fails on Mavericks and Xcode 5.1 - unknown argument: '-multiply_definedsuppress'

I was trying run gem install json and got the following error

Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

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

make "DESTDIR=" clean

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

make failed, exit code 2

Gem files will remain installed in /opt/boxen/repo/.bundle/ruby/2.0.0/gems/json-1.8.0 for inspection.
Results logged to /opt/boxen/repo/.bundle/ruby/2.0.0/extensions/universal-darwin-13/2.0.0/json-1.8.0/gem_make.out

I'm using:

Os X: 10.9.2
Xcode: 5.1 Build version 5B130a
Command Line Tools (CLT): 5.1.0.0.1.1393561416
Ruby: ruby 2.0.0p247 (2013-06-27 revision 41674) [universal.x86_64-darwin13]
Ruby Gem: 2.2.2
GCC: 4.2.1 Apple LLVM version 5.1 (clang-503.0.38) (based on LLVM 3.4svn)

I am encountering the exact same problem after updating Xcode to 5.1 and news from Apple aren't good. From Xcode 5.1 Release Notes:

> - The Apple LLVM compiler in Xcode 5.1 treats unrecognized command-line options as errors. This issue has been seen when building both Python native extensions and Ruby Gems, where some invalid compiler options are currently specified. > >Projects using invalid compiler options will need to be changed to remove those options. To help ease that transition, the compiler will temporarily accept an option to downgrade the error to a warning: > > -Wno-error=unused-command-line-argument-hard-error-in-future > > To workaround this issue, set the ARCHFLAGS environment variable to downgrade the error to a warning. > > ARCHFLAGS=-Wno-error=unused-command-line-argument-hard-error-in-future gem install GemName

It seems that all gems violating the compiler options must be updated to use valid options. It is explicitly stated that: This option [downgrading error to warning] will not be supported in the future.

The clang note we are seeing (this will be a hard error (cannot be downgraded to a warning) in the future) corresponds to the change announced in the release notes.

---

To answer your question specifically, use the following to install the json gem:

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

Note, however, that this is only a temporary fix.

One-liner to fix that

curl https://gist.githubusercontent.com/Paulche/9713531/raw/1e57fbb440d36ca5607d1739cc6151f373b234b6/gistfile1.txt | sudo patch /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/universal-darwin13/rbconfig.rb

To address the issue you can install the most recent version of ruby as described by @Sash. You can use the following commands to do so. In case you already have installed rvm, you don't need to reinstall it.

#Install rvm
\curl -sSL https://get.rvm.io | bash -s stable

#Install ruby version 2.0.0-p451
rvm install ruby-2.0.0-p451

#Print ruby version to verify that it was installed successfully
ruby -v

#Install json gem
sudo gem install json

Issue already addressed by Ruby:

https://bugs.ruby-lang.org/issues/9624

now we just need to wait for Apple to update their ruby version (2.0.0p247) to the one after the latest one (2.0.0p451) which hasn't come out yet ... (or brew/macport it)

Update (2014-05-15): Mavericks 10.9.3 updates ruby to

ruby 2.0.0p451 (2014-02-24 revision 45167) [universal.x86_64-darwin13] 

And this seems to resolves the issue.

@Muncken has already provided an answer to install gem one by one:

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

Base on Muncken's answer, I've tried that it also works when using bundle install

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

In my case, I actually have similar problem, but not on the system ruby, but on rubies installed by rvm from OSX 10.8, and it has issues after upgrading to OSX 10.9.

A simple reinstall works: rvm reinstall ruby-2.1.1

On OSX 10.10, I had several issues when running rails new firstapp such as:

ERROR:  Error installing json:
ERROR: Failed to build gem native extension.
fatal error: 'ruby/config.h' file not found

I updated rvm with this configuration and all the errors are gone!:

rvm get stable --auto-dotfiles

You can tell from the app name that I just started fiddling with Ruby on Rails, so the above advice may or may not work for you.

Paul Chechetin's one-liner doesn't appear to work anymore (9/21/15). However, this reply to the post mentioned in Pete's reply solved the problem for me:

• (a) Install Apple's XCode, then (b) launch it and accept the licensing terms (I had done (a), but not (b).)
• sudo gem uninstall compass
• sudo gem install compass

None of these worked for me.

What finally worked is running the command with a sudo -

gem install byebug -v '9.0.6'

It's been a while and I've got similar error. An alternative to folks using bundler is to add the flag to the build configuration like below example:

bundle config build.<gemname> --with-cflags="-Wno-error=implicit-function-declaration"

followed by

bundle install

Please note that you must replace <gemname> above with the name of the actual gem that is throwing the error while building native extensions.

I hope this becomes helpful to others that face similar issues in the future!

I used a simple solution... install through brew

brew install name