wc-ac.php

<?php
/**
 * Autocomplete Paid Orders (WC 2.2+)
 */
add_filter( 'woocommerce_payment_complete_order_status', 'bryce_wc_autocomplete_paid_paypal_orders' );
function bryce_wc_autocomplete_paid_paypal_orders( $order_status, $order_id ) {
	
	$order = wc_get_order( $order_id );
	if ( $order->payment_method == 'paypal' ) {
  		if ( $order_status == 'processing' && ( $order->status == 'on-hold' || $order->status == 'pending' || $order->status == 'failed' ) ) {
  			return 'completed';
  		}
	}
	
	return $order_status;
}