I keep getting this error

Mcrypt PHP extension required

at the bottom after I run a composer update :

Since I am using Mac, I have tried running :

brew search mcrypt brew install php56-mcrypt

I still get the same error message.

Steps

I solved this by running the following commands

brew update
brew upgrade
brew tap homebrew/dupes
brew tap josegonzalez/homebrew-php
brew install php54-mcrypt
php --version // To Test your php 
sudo composer update

Result

No more Mcrypt warning !!

Loading composer repositories with package information
Updating dependencies (including require-dev)
Nothing to install or update
Generating autoload files
Generating optimized class loader