Date/Time, PHP Compat: Prevent type errors using GMT offset option.

Prevents a potential type errors when making use of the `gmt_offset` option by casting the value to a float prior to performing calculations with the value.

This mainly accounts for incorrect storage of values, such as an empty string or city name.

Follow up to [58923].

Props chaion07, hellofromtonya, kirasong, mhshohel, mukesh27, nicolefurlan, nihar007, nurielmeni, oglekler, peterwilsoncc, prionkor, rajinsharwar, rarst, rleeson, sabernhardt, SergeyBiryukov, swissspidy, toastercookie, verygoode.
Fixes #56358, #58986, #60629.


git-svn-id: https://develop.svn.wordpress.org/trunk@59064 602fd350-edb4-49c9-b593-d223f7449a82

Author: peterwilsoncc

src/wp-admin/update-core.php

@@ -1096,7 +1096,7 @@ function do_undismiss_core_update() {
 	$current           = get_site_transient( 'update_core' );
 
 	if ( $current && isset( $current->last_checked ) ) {
-		$last_update_check = $current->last_checked + get_option( 'gmt_offset' ) * HOUR_IN_SECONDS;
+		$last_update_check = $current->last_checked + (int) ( (float) get_option( 'gmt_offset' ) * HOUR_IN_SECONDS );
 	}
 
 	echo '<h2 class="wp-current-version">';

src/wp-includes/bookmark-template.php

@@ -90,7 +90,7 @@ function _walk_bookmarks( $bookmarks, $args = '' ) {
 					__( 'Last updated: %s' ),
 					gmdate(
 						get_option( 'links_updated_date_format' ),
-						$bookmark->link_updated_f + ( get_option( 'gmt_offset' ) * HOUR_IN_SECONDS )
+						$bookmark->link_updated_f + (int) ( (float) get_option( 'gmt_offset' ) * HOUR_IN_SECONDS )
 					)
 				);
 				$title .= ')';

src/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php

@@ -1816,7 +1816,7 @@ public function prepare_item_for_response( $item, $request ) {
 			 * with the site's timezone offset applied.
 			 */
 			if ( '0000-00-00 00:00:00' === $post->post_modified_gmt ) {
-				$post_modified_gmt = gmdate( 'Y-m-d H:i:s', strtotime( $post->post_modified ) - ( get_option( 'gmt_offset' ) * HOUR_IN_SECONDS ) );
+				$post_modified_gmt = gmdate( 'Y-m-d H:i:s', strtotime( $post->post_modified ) - (int) ( (float) get_option( 'gmt_offset' ) * HOUR_IN_SECONDS ) );
 			} else {
 				$post_modified_gmt = $post->post_modified_gmt;
 			}

src/wp-mail.php

@@ -44,7 +44,7 @@
 
 set_transient( 'mailserver_last_checked', true, WP_MAIL_INTERVAL );
 
-$time_difference = get_option( 'gmt_offset' ) * HOUR_IN_SECONDS;
+$time_difference = (int) ( (float) get_option( 'gmt_offset' ) * HOUR_IN_SECONDS );
 
 $phone_delim = '::';