Cleaning WP from any reference to php4

[arena]

I think the time as come !

​PHP 4 and MySQL 4 End of Life Announcement
Posted July 23, 2010 by Mark Jaquith. Filed under Hosting.

wp51\wp-admin\includes\class-ftp.php
    281: // Validate the IPAddress PHP4 returns -1 for invalid, PHP5 false
wp51\wp-admin\includes\deprecated.php
    504: * PHP4 Constructor - Sets up the object properties.
wp51\wp-admin\includes\file.php
    201: 'php4',
    258: 'php4',
wp51\wp-includes\IXR\class-IXR-base64.php
     22: * PHP4 constructor.
wp51\wp-includes\IXR\class-IXR-client.php
     55: * PHP4 constructor.
wp51\wp-includes\IXR\class-IXR-clientmulticall.php
     22: * PHP4 constructor.
wp51\wp-includes\IXR\class-IXR-date.php
     32: * PHP4 constructor.
wp51\wp-includes\IXR\class-IXR-error.php
     24: * PHP4 constructor.
wp51\wp-includes\IXR\class-IXR-introspectionserver.php
     52: * PHP4 constructor.
wp51\wp-includes\IXR\class-IXR-message.php
     39: * PHP4 constructor.
wp51\wp-includes\IXR\class-IXR-request.php
     39: * PHP4 constructor.
wp51\wp-includes\IXR\class-IXR-server.php
     32: * PHP4 constructor.
wp51\wp-includes\IXR\class-IXR-value.php
     36: * PHP4 constructor.
wp51\wp-includes\pomo\entry.php
     67: * PHP4 constructor.
wp51\wp-includes\pomo\streams.php
     26: * PHP4 constructor.
    152: * PHP4 constructor.
    231: * PHP4 constructor.
    297: * PHP4 constructor.
    318: * PHP4 constructor.
wp51\wp-includes\Text\Diff\Renderer.php
     47: * PHP4 constructor.
wp51\wp-includes\Text\Diff.php
     59: * PHP4 constructor.
    339: * PHP4 constructor.
    398: * PHP4 constructor.
    430: * PHP4 constructor.
    462: * PHP4 constructor.
    494: * PHP4 constructor.
wp51\wp-includes\atomlib.php
    102: * PHP4 constructor.
wp51\wp-includes\cache.php
    740: * @todo This should be moved to the PHP4 style constructor, PHP5
wp51\wp-includes\class-json.php
    152: * PHP4 constructor.
    950: * PHP4 constructor.
wp51\wp-includes\class-phpass.php
     59: * PHP4 constructor.
wp51\wp-includes\class-phpmailer.php
   3558: 'php4'  => 'application/x-httpd-php',
wp51\wp-includes\class-pop3.php
     69: * PHP4 constructor.
    657: // For php4 compatibility
wp51\wp-includes\class-wp-widget.php
    177: * PHP4 constructor.
wp51\wp-includes\class-wp-widget-factory.php
     36: * PHP4 constructor.
wp51\wp-includes\functions.php
   4348: * remove PHP4 style constructors.
   4352: * This function is to be used in every PHP4 style constructor method that is deprecated.
wp51\wp-includes\general-template.php
   3437: case 'php4':
wp51\wp-includes\rss.php
    102: * PHP4 constructor.
    735: * PHP4 constructor.

[desrosj]

Related: #21402.

This is something that will need to land early so any issues can be found and corrected. When we move forward with this, we should break each file into a different ticket to make it easier to test.

Also, several of the files included in the list (PHPMailer, Diff, etc.) are external libraries. These will need to be removed upstream before being merged back into WordPress separately.