The 'ffi' native gem requires installed build tools

For Windows people who've never had experience with Ruby, Gems etc.

Recently on a windows box, I had a need to install compass fresh. Not because I wanted to create a gem but just to use features like sass etc. I did following steps:

1. Installed Ruby from http://rubyinstaller.org/

2. checked version

C:\ruby --version

which returned

ruby 2.2.1p85 (2015-02-26 revision 49769) [x64-mingw32]

indicating successful ruby installation

3. executed gem update --system so that all gems are up-to-date

4. gem install -compass  it failed with following error:

C:\Users\deepak.aggarwal>gem install compass

ERROR:  Error installing compass:

        The 'ffi' native gem requires installed build tools.

Please update your PATH to include build tools or download the DevKit

from 'http://rubyinstaller.org/downloads' and follow the instructions

at 'http://github.com/oneclick/rubyinstaller/wiki/Development-Kit'

After re-installing many times and then installing devkit from download page (which initself is a big list of task) I realized I didn't need any of that....

All I had to do execute in command prompt was:

gem install ffi

And then gem install compass worked fine

NOTES:

1. You'll also see similar error if you already have a component installed. Always execute following command to double check that the component you're trying is not already there

gem list --local

2. You don't need to install or do anything with devkit (unless you want to create native gems)

3. Following is my result of listing.. You can compare missing ones and install everything as-is by explicitly specifying versions

bigdecimal (1.2.6)

chunky_png (1.3.4)

compass (1.0.3)

compass-core (1.0.3)

compass-import-once (1.0.5)

ffi (1.9.8 x64-mingw32)

io-console (0.4.3)

json (1.8.1)

minitest (5.4.3)

multi_json (1.11.1)

power_assert (0.2.2)

psych (2.0.8)

rake (10.4.2)

rb-fsevent (0.9.5)

rb-inotify (0.9.5)

rdoc (4.2.0)

rubygems-update (2.4.8)

sass (3.4.13)

test-unit (3.0.8)

toolkit (2.9.0)

You do so by using v switch. Like

gem install compass -v 1.0.3

Big thanks to my colleague Gaurav Mehra whose installed gems I referred to find that ffi culprit

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