ERROR: Failed to build gem native extension.

[loretoparisi]

MacBook-Pro-di-Loreto:appledoc admin$ sudo gem install cupertino
Building native extensions. This could take a while...
ERROR: Error installing cupertino:
ERROR: Failed to build gem native extension.

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

mkmf.rb can't find header files for ruby at /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/include/ruby.h

Gem files will remain installed in /Library/Ruby/Gems/2.0.0/gems/nokogiri-1.5.11 for inspection.
Results logged to /Library/Ruby/Gems/2.0.0/gems/nokogiri-1.5.11/ext/nokogiri/gem_make.out

[pcholberg]

http://stackoverflow.com/questions/19580685/installing-rails-on-mavericks
The same issue, installing command line tools:
xcode-select --install
must fix this.

[mattt]

Thanks, @pcholberg. 783a43f adds a note about this in the README.

[billyto]

If you're running Xcode 5.1, the command line tools don't work for nokogiri. You'll need to download the Late october 2013 tools from Apple. Once you do that run

sudo xcode-select -s /Library/Developer/CommandLineTools/

to set up your machine to use the Xcode 5.0.X command line tools, then run

gem install cupertino
If you want to reset your command line tools to the Xcode.app version afterward run

sudo xcode-select -r

More info on stackoverflow

[bteschke]

I was getting an unused argument error for nokogiri with Xcode 5.1 but it was fixed by adding this to the beginning of the gem install command.

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

[billyto]

Way better solution!

Thanks.

[apolishch]

neither one of these solutions worked for me

[biddster]

Just for future reference, here's how I got cupertino running on mavericks:

$ sudo xcode-select --switch /Library/Developer/CommandLineTools/
$ sudo ARCHFLAGS=-Wno-error=unused-command-line-argument-hard-error-in-future gem install nokogiri -v 1.5.11
$ sudo gem install cupertino

I had to explicitly install nokogiri 1.5.11 as that's the version that cupertino appears to depend on.

Note that I already had the latest command line tools installed.

[gnustep]

Still having this issue:

glados:cupertino heron$ sudo xcode-select -s /Library/Developer/CommandLineTools/
Password:
glados:cupertino heron$ sudo ARCHFLAGS=-Wno-error=unused-command-line-argument-hard-error-in-future gem install nokogiri -v 1.5.11
Building native extensions. This could take a while...
Successfully installed nokogiri-1.5.11
Parsing documentation for nokogiri-1.5.11
Installing ri documentation for nokogiri-1.5.11
Done installing documentation for nokogiri after 10 seconds
1 gem installed
glados:cupertino heron$ sudo gem install cupertino
Building native extensions. This could take a while...
ERROR: Error installing cupertino:
ERROR: Failed to build gem native extension.

/usr/local/Cellar/ruby/2.1.2/bin/ruby extconf.rb

checking for main() in -lstdc++... yes
checking for ruby/encoding.h... yes
creating Makefile

make "DESTDIR=" clean

make "DESTDIR="
compiling unf.cc
In file included from unf.cc:1:
./unf/normalizer.hh:4:10: fatal error: 'vector' file not found
#include
^
1 error generated.
make: *** [unf.o] Error 1

make failed, exit code 2

Gem files will remain installed in /usr/local/Cellar/ruby/2.1.2/lib/ruby/gems/2.1.0/gems/unf_ext-0.0.6 for inspection.
Results logged to /usr/local/Cellar/ruby/2.1.2/lib/ruby/gems/2.1.0/extensions/x86_64-darwin-13/2.1.0/unf_ext-0.0.6/gem_make.out
glados:cupertino heron$

[cp3hnu]

Thanks, @biddster.It works for me.

[crrobinson14]

The workaround listed by @biddster works for me, too.

[csmobile]

Thank you @biddster. This worked for me as well.

[adison]

@biddster is right, nokogiri 1.5.11 works

[cezheng]

@gnustep How did you resolve that problem? I'm installing another Gem that uses unf_ext, and I'm having exactly the same problem as yours with Xcode 7.3.1

compiling unf.cc
In file included from unf.cc:1:
./unf/normalizer.hh:4:10: fatal error: 'vector' file not found
#include <vector>
         ^
1 error generated.
make: *** [unf.o] Error 1

make failed, exit code 2