gem install ffi -v '1.1.5' osx 10.8

Question

I been trying to install ffi on OSX 10.8 via

gem install ffi -v '1.1.5'

with the result

ERROR:  Error installing ffi:
ERROR: Failed to build gem native extension.

/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby extconf.rb
checking for ffi.h... no
checking for ffi.h in /usr/local/include,/usr/include/ffi... no
checking for rb_thread_blocking_region()... no
checking for ruby_native_thread_p()... no
checking for rb_thread_call_with_gvl()... no
creating extconf.h
creating Makefile

make
mkdir -p "/Library/Ruby/Gems/1.8/gems/ffi-1.1.5/ext/ffi_c"/libffi-i386; (if [ ! -f       "/Library/Ruby/Gems/1.8/gems/ffi-1.1.5/ext/ffi_c"/libffi-i386/Makefile ]; then echo "Configuring libffi for i386"; cd "/Library/Ruby/Gems/1.8/gems/ffi-1.1.5/ext/ffi_c"/libffi-i386 && env CC=" xcrun cc" CFLAGS="-arch i386 " LDFLAGS="-arch i386" "/Library/Ruby/Gems/1.8/gems/ffi-1.1.5/ext/ffi_c/libffi"/configure --disable-static --with-pic=yes --disable-dependency-tracking --host=i386-apple-darwin > /dev/null; fi); env MACOSX_DEPLOYMENT_TARGET=10.4 make -C "/Library/Ruby/Gems/1.8/gems/ffi-1.1.5/ext/ffi_c"/libffi-i386
Configuring libffi for i386
configure: WARNING: if you wanted to set the --build type, don't use --host.
If a cross compiler is detected then cross compile mode will be used
configure: error: in `/Library/Ruby/Gems/1.8/gems/ffi-1.1.5/ext/ffi_c/libffi-i386':
configure: error: C compiler cannot create executables
See `config.log' for more details
make[1]: *** No targets specified and no makefile found.  Stop.
make: *** ["/Library/Ruby/Gems/1.8/gems/ffi-1.1.5/ext/ffi_c"/libffi-   i386/.libs/libffi_convenience.a] Error 2


Gem files will remain installed in /Library/Ruby/Gems/1.8/gems/ffi-1.1.5 for inspection.
Results logged to /Library/Ruby/Gems/1.8/gems/ffi-1.1.5/ext/ffi_c/gem_make.out

I have tried to follow

An error occured while installing ffi (1.1.2), and Bundler cannot continue

and

Not able to install some gems after mountain lion upgrade

without any luck.

Answer 1

My ffi installation failed with a pretty similar error message:

mkdir -p "/Library/Ruby/Gems/1.8/gems/ffi-1.9.0/ext/ffi_c"/libffi-i386; (if [ ! -f "/Library/Ruby/Gems/1.8/gems/ffi-1.9.0/ext/ffi_c"/libffi-i386/Makefile ]; then echo "Configuring libffi for i386"; cd "/Library/Ruby/Gems/1.8/gems/ffi-1.9.0/ext/ffi_c"/libffi-i386 && env CC=" xcrun cc" CFLAGS="-arch i386 " LDFLAGS="-arch i386" "/Library/Ruby/Gems/1.8/gems/ffi-1.9.0/ext/ffi_c/libffi"/configure --disable-static --with-pic=yes --disable-dependency-tracking --host=i386-apple-darwin > /dev/null; fi); env MACOSX_DEPLOYMENT_TARGET=10.4 make -C "/Library/Ruby/Gems/1.8/gems/ffi-1.9.0/ext/ffi_c"/libffi-i386
Configuring libffi for i386
configure: WARNING: if you wanted to set the --build type, don't use --host.
    If a cross compiler is detected then cross compile mode will be used
configure: error: in `/Library/Ruby/Gems/1.8/gems/ffi-1.9.0/ext/ffi_c/libffi-i386':
configure: error: C compiler cannot create executables

I spotted xcrun cc in the command and trying to run it manually gave me Apple's message that I had not agreed to XCode command line tools' license agreement. After the sudo xcrun cc the installation succeeded.

$ xcrun cc
Agreeing to the Xcode/iOS license requires admin privileges, please re-run as root via sudo.
$ sudo xcrun cc
You have not agreed to the Xcode license agreements. You must agree to both license agreements below in order to use Xcode.
Hit the Enter key to view the license agreements at '/Applications/Xcode.app/Contents/Resources/English.lproj/License.rtf'
...

```