phpdcd is a Dead Code Detector (DCD) for PHP code. It scans a PHP project for all declared functions and methods and reports those as being "dead code" that are not called at least once.

As PHP is a very dynamic programming language, the static analysis performed by phpdcd does not recognize function or method calls that are performed using one of the following language features:

• Reflection API
• call_user_func() and call_user_func_array()
• Usage of the new operator with variable class names
• Variable class names for static method calls such as $class::method()
• Variable function or method names such as $function() or $object->$method()
• Automatic calls to methods such as __toString() or Iterator::*()

Also note that infering the type of a variable is limited to type-hinted arguments (function foo(Bar $bar) {}) and direct object creation ($object = new Clazz)

The easiest way to obtain PHPDCD is to download a PHP Archive (PHAR) that has all required dependencies of PHPDCD bundled in a single file:

wget https://phar.phpunit.de/phpdcd.phar
chmod +x phpdcd.phar
mv phpdcd.phar /usr/local/bin/phpdcd

You can also immediately use the PHAR after you have downloaded it, of course:

wget https://phar.phpunit.de/phpdcd.phar
php phpdcd.phar

Simply add a dependency on sebastian/phpdcd to your project's composer.json file if you use Composer to manage the dependencies of your project. Here is a minimal example of a composer.json file that just defines a development-time dependency on PHPDCD:

{
    "require-dev": {
        "sebastian/phpdcd": "*"
    }
}

For a system-wide installation via Composer, you can run:

composer global require 'sebastian/phpdcd=*'

Make sure you have ~/.composer/vendor/bin/ in your path.