Error installing/bundling gem unf_ext -v '0.0.6'

Question

I'm trying to bundle intall unf_ext -v '0.0.6' but I keep getting this error:

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

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:
In file included from ./unf/normalizer.hh:4:
In file included from /Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/vector:265:
In file included from /Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/__bit_reference:15:
In file included from /Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/algorithm:628:
In file included from /Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/memory:604:
/Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/iterator:341:10: fatal error: '__debug' file not found
#include <__debug>
         ^
1 error generated.
make: *** [unf.o] Error 1

make failed, exit code 2

I've run gem update --system and i've brew install coreutils but I'm still getting the same error.

Update: Answer
Downloaded and installed commandlinetoolsosx10.10forxcode6.2.dmg from Apple Developer. No need to uninstall anything.

Answer 1

It's a bug in the new xcode tools. It broke eventmachine in my case. See Missing C++ header <__debug> after updating OSX Command Line Tools 6.3 for answers with dummy files and reinstallation links. I downgraded to 6.2 and the problem went away.

Answer 2

Doing this worked for me:

echo '#define _LIBCPP_ASSERT(x, m) ((void)0)' | sudo tee -a /Library/Developer/CommandLineTools/usr/include/c++/v1/__debug > /dev/null

Then run bundle again.

And, since this is only meant to be a temporary fix until Apple releases a patch, remove that newly created file with:

sudo rm /Library/Developer/CommandLineTools/usr/include/c++/v1/__debug