Redirect to Cart page when shipping info is not filled yet

checkout-redirect-patch.diff

diff --git a/wordpress/wp-content/plugins/woocommerce/includes/class-wc-cart.php b/wordpress/wp-content/plugins/woocommerce/includes/class-wc-cart.php
index 5563396..681a859 100644
--- a/wordpress/wp-content/plugins/woocommerce/includes/class-wc-cart.php
+++ b/wordpress/wp-content/plugins/woocommerce/includes/class-wc-cart.php
@@ -105,6 +105,7 @@ class WC_Cart {
         * Constructor for the cart class. Loads options and hooks in the init method.
         */
        public function __construct() {
+               add_action( 'wp_head', array( $this, 'force_shipping_to_be_set_on_checkout' ) );
                add_action( 'wp_loaded', array( $this, 'init' ) ); // Get cart after WP and plugins are loaded.
                add_action( 'wp', array( $this, 'maybe_set_cart_cookies' ), 99 ); // Set cookies
                add_action( 'shutdown', array( $this, 'maybe_set_cart_cookies' ), 0 ); // Set cookies before shutdown and ob flushing
@@ -1617,6 +1618,22 @@ class WC_Cart {
                }

        /*-----------------------------------------------------------------------------------*/
+       /* Custom functions
+       /*-----------------------------------------------------------------------------------*/
+
+               /**
+                * Certifies that user gets redirected to Cart page if shipping is enabled, mandatory but the user didn't set to where he wants the products to be delivered.
+                * This will only happen if in Checkout page.
+                */
+               public function force_shipping_to_be_set_on_checkout() {
+                       if ( is_checkout() && $this->needs_shipping() && empty( WC()->customer->get_shipping_postcode() ) ) {
+                               wc_add_notice( __( 'Before going to Checkout page you need to set your shipping information', 'woocommerce' ), 'error' );
+                               wp_redirect( wc_get_page_permalink( 'cart' ) );
+                               exit();
+                       }
+               }
+
+       /*-----------------------------------------------------------------------------------*/
        /* Coupons/Discount related functions */
        /*-----------------------------------------------------------------------------------*/