From 1ce5dc7444eae8cf284f2118b085ad98603a754a Mon Sep 17 00:00:00 2001
From: Sergey Biryukov <sergeybiryukov.ru@gmail.com>
Date: Thu, 22 Jun 2023 14:36:26 +0000
Subject: [PATCH] Code Modernization: Replace usage of `strpos()` with
 `str_contains()`.

`str_contains()` was introduced in PHP 8.0 to perform a case-sensitive check indicating if the string to search in (haystack) contains the given substring (needle).

WordPress core includes a polyfill for `str_contains()` on PHP < 8.0 as of WordPress 5.9.

This commit replaces `false !== strpos( ... )` with `str_contains()` in core files, making the code more readable and consistent, as well as better aligned with modern development practices.

Follow-up to [52039], [52040], [52326], [55703], [55710], [55987].

Props Soean, spacedmonkey, costdev, dingo_d, azaozz, mikeschroder, flixos90, peterwilsoncc, SergeyBiryukov.
Fixes #58206.
Built from https://develop.svn.wordpress.org/trunk@55988


git-svn-id: http://core.svn.wordpress.org/trunk@55500 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-admin/comment.php                          |  2 +-
 wp-admin/edit.php                             |  2 +-
 wp-admin/includes/ajax-actions.php            |  4 +-
 .../class-automatic-upgrader-skin.php         |  2 +-
 .../includes/class-bulk-upgrader-skin.php     |  2 +-
 wp-admin/includes/class-core-upgrader.php     |  6 +--
 .../includes/class-custom-image-header.php    |  6 +--
 wp-admin/includes/class-ftp.php               |  2 +-
 .../includes/class-wp-ajax-upgrader-skin.php  |  2 +-
 .../includes/class-wp-automatic-updater.php   |  6 +--
 .../includes/class-wp-ms-sites-list-table.php |  2 +-
 .../class-wp-plugin-install-list-table.php    |  2 +-
 .../class-wp-site-health-auto-updates.php     |  4 +-
 wp-admin/includes/class-wp-site-health.php    |  4 +-
 wp-admin/includes/class-wp-upgrader-skin.php  |  2 +-
 wp-admin/includes/credits.php                 |  2 +-
 wp-admin/includes/deprecated.php              |  2 +-
 wp-admin/includes/file.php                    |  4 +-
 wp-admin/includes/media.php                   |  6 +--
 wp-admin/includes/misc.php                    |  8 ++--
 wp-admin/includes/plugin.php                  |  4 +-
 wp-admin/includes/post.php                    |  6 +--
 wp-admin/includes/privacy-tools.php           |  2 +-
 wp-admin/includes/template.php                |  2 +-
 wp-admin/includes/update-core.php             |  6 +--
 wp-admin/includes/upgrade.php                 |  6 +--
 wp-admin/includes/user.php                    |  2 +-
 wp-admin/menu-header.php                      |  2 +-
 wp-admin/network/site-settings.php            |  2 +-
 wp-admin/network/themes.php                   |  2 +-
 wp-admin/options-general.php                  |  2 +-
 wp-admin/options.php                          |  2 +-
 wp-admin/post.php                             |  6 +--
 wp-admin/upload.php                           |  2 +-
 wp-admin/user-edit.php                        |  2 +-
 wp-admin/user-new.php                         |  2 +-
 wp-admin/widgets-form.php                     |  2 +-
 .../twentyseventeen/inc/icon-functions.php    |  2 +-
 .../template-parts/post/content-audio.php     |  2 +-
 .../template-parts/post/content-video.php     |  2 +-
 wp-content/themes/twentytwenty/comments.php   |  2 +-
 wp-content/themes/twentytwenty/functions.php  |  2 +-
 .../template-parts/pagination.php             |  4 +-
 .../inc/template-functions.php                |  2 +-
 wp-includes/block-supports/duotone.php        |  4 +-
 wp-includes/block-template.php                |  2 +-
 wp-includes/blocks.php                        |  8 ++--
 wp-includes/canonical.php                     |  6 +--
 wp-includes/class-wp-comment-query.php        |  2 +-
 wp-includes/class-wp-customize-manager.php    |  2 +-
 wp-includes/class-wp-date-query.php           |  2 +-
 wp-includes/class-wp-editor.php               |  4 +-
 wp-includes/class-wp-http-proxy.php           |  2 +-
 wp-includes/class-wp-http.php                 |  8 ++--
 wp-includes/class-wp-meta-query.php           |  2 +-
 wp-includes/class-wp-oembed.php               |  2 +-
 wp-includes/class-wp-post-type.php            |  2 +-
 wp-includes/class-wp-query.php                | 10 ++---
 wp-includes/class-wp-rewrite.php              |  4 +-
 wp-includes/class-wp-site-query.php           |  2 +-
 wp-includes/class-wp-user-query.php           |  2 +-
 wp-includes/class-wp-xmlrpc-server.php        |  2 +-
 wp-includes/class-wp.php                      |  8 ++--
 wp-includes/class-wpdb.php                    |  4 +-
 wp-includes/comment-template.php              |  6 +--
 wp-includes/comment.php                       |  2 +-
 wp-includes/cron.php                          |  2 +-
 wp-includes/deprecated.php                    |  6 +--
 wp-includes/feed.php                          |  8 ++--
 wp-includes/formatting.php                    | 42 +++++++++----------
 wp-includes/functions.php                     | 34 +++++++--------
 wp-includes/general-template.php              |  8 ++--
 wp-includes/global-styles-and-settings.php    |  2 +-
 wp-includes/https-detection.php               |  4 +-
 wp-includes/kses.php                          |  2 +-
 wp-includes/link-template.php                 |  8 ++--
 wp-includes/media.php                         | 36 ++++++++--------
 wp-includes/ms-deprecated.php                 |  4 +-
 wp-includes/ms-files.php                      |  2 +-
 wp-includes/ms-functions.php                  |  4 +-
 wp-includes/pluggable.php                     |  8 ++--
 wp-includes/pomo/po.php                       |  2 +-
 wp-includes/post-template.php                 |  2 +-
 wp-includes/post.php                          | 14 +++----
 .../rest-api/class-wp-rest-request.php        |  2 +-
 .../class-wp-rest-autosaves-controller.php    |  2 +-
 .../class-wp-rest-plugins-controller.php      |  4 +-
 .../class-wp-rest-users-controller.php        |  2 +-
 wp-includes/revision.php                      |  6 +--
 wp-includes/rewrite.php                       |  6 +--
 wp-includes/script-loader.php                 |  4 +-
 wp-includes/shortcodes.php                    | 12 +++---
 wp-includes/template.php                      |  2 +-
 wp-includes/user.php                          |  4 +-
 wp-includes/vars.php                          | 34 +++++++--------
 wp-includes/version.php                       |  2 +-
 wp-includes/widgets/class-wp-widget-text.php  |  4 +-
 wp-load.php                                   |  2 +-
 wp-login.php                                  |  4 +-
 wp-mail.php                                   |  2 +-
 wp-trackback.php                              |  2 +-
 101 files changed, 253 insertions(+), 253 deletions(-)

diff --git a/wp-admin/comment.php b/wp-admin/comment.php
index 17f85a093a..ccb72c0910 100644
--- a/wp-admin/comment.php
+++ b/wp-admin/comment.php
@@ -282,7 +282,7 @@ switch ( $action ) {
 			comment_footer_die( __( 'Sorry, you are not allowed to edit comments on this post.' ) );
 		}
 
-		if ( wp_get_referer() && ! $noredir && false === strpos( wp_get_referer(), 'comment.php' ) ) {
+		if ( wp_get_referer() && ! $noredir && ! str_contains( wp_get_referer(), 'comment.php' ) ) {
 			$redir = wp_get_referer();
 		} elseif ( wp_get_original_referer() && ! $noredir ) {
 			$redir = wp_get_original_referer();
diff --git a/wp-admin/edit.php b/wp-admin/edit.php
index 7361aa1d40..c2a2b6990c 100644
--- a/wp-admin/edit.php
+++ b/wp-admin/edit.php
@@ -81,7 +81,7 @@ if ( $doaction ) {
 		$sendback = admin_url( $parent_file );
 	}
 	$sendback = add_query_arg( 'paged', $pagenum, $sendback );
-	if ( strpos( $sendback, 'post.php' ) !== false ) {
+	if ( str_contains( $sendback, 'post.php' ) ) {
 		$sendback = admin_url( $post_new_file );
 	}
 
diff --git a/wp-admin/includes/ajax-actions.php b/wp-admin/includes/ajax-actions.php
index b993271ab4..ad48c2f3b4 100644
--- a/wp-admin/includes/ajax-actions.php
+++ b/wp-admin/includes/ajax-actions.php
@@ -126,7 +126,7 @@ function wp_ajax_ajax_tag_search() {
 		$search = str_replace( $comma, ',', $search );
 	}
 
-	if ( false !== strpos( $search, ',' ) ) {
+	if ( str_contains( $search, ',' ) ) {
 		$search = explode( ',', $search );
 		$search = $search[ count( $search ) - 1 ];
 	}
@@ -2306,7 +2306,7 @@ function wp_ajax_widgets_order() {
 				$val = explode( ',', $val );
 
 				foreach ( $val as $k => $v ) {
-					if ( strpos( $v, 'widget-' ) === false ) {
+					if ( ! str_contains( $v, 'widget-' ) ) {
 						continue;
 					}
 
diff --git a/wp-admin/includes/class-automatic-upgrader-skin.php b/wp-admin/includes/class-automatic-upgrader-skin.php
index 15ea79f5f4..4fee6205fc 100644
--- a/wp-admin/includes/class-automatic-upgrader-skin.php
+++ b/wp-admin/includes/class-automatic-upgrader-skin.php
@@ -84,7 +84,7 @@ class Automatic_Upgrader_Skin extends WP_Upgrader_Skin {
 			$string = $this->upgrader->strings[ $string ];
 		}
 
-		if ( strpos( $string, '%' ) !== false ) {
+		if ( str_contains( $string, '%' ) ) {
 			if ( ! empty( $args ) ) {
 				$string = vsprintf( $string, $args );
 			}
diff --git a/wp-admin/includes/class-bulk-upgrader-skin.php b/wp-admin/includes/class-bulk-upgrader-skin.php
index 2b85c67cb7..71a779c594 100644
--- a/wp-admin/includes/class-bulk-upgrader-skin.php
+++ b/wp-admin/includes/class-bulk-upgrader-skin.php
@@ -59,7 +59,7 @@ class Bulk_Upgrader_Skin extends WP_Upgrader_Skin {
 			$feedback = $this->upgrader->strings[ $feedback ];
 		}
 
-		if ( strpos( $feedback, '%' ) !== false ) {
+		if ( str_contains( $feedback, '%' ) ) {
 			if ( $args ) {
 				$args     = array_map( 'strip_tags', $args );
 				$args     = array_map( 'esc_html', $args );
diff --git a/wp-admin/includes/class-core-upgrader.php b/wp-admin/includes/class-core-upgrader.php
index 59d1bc791e..138f904e22 100644
--- a/wp-admin/includes/class-core-upgrader.php
+++ b/wp-admin/includes/class-core-upgrader.php
@@ -181,9 +181,9 @@ class Core_Upgrader extends WP_Upgrader {
 				 * mkdir_failed__copy_dir, copy_failed__copy_dir_retry, and disk_full.
 				 * do_rollback allows for update_core() to trigger a rollback if needed.
 				 */
-				if ( false !== strpos( $error_code, 'do_rollback' ) ) {
+				if ( str_contains( $error_code, 'do_rollback' ) ) {
 					$try_rollback = true;
-				} elseif ( false !== strpos( $error_code, '__copy_dir' ) ) {
+				} elseif ( str_contains( $error_code, '__copy_dir' ) ) {
 					$try_rollback = true;
 				} elseif ( 'disk_full' === $error_code ) {
 					$try_rollback = true;
@@ -323,7 +323,7 @@ class Core_Upgrader extends WP_Upgrader {
 			}
 
 			// Don't claim we can update on update-core.php if we have a non-critical failure logged.
-			if ( $wp_version === $failure_data['current'] && false !== strpos( $offered_ver, '.1.next.minor' ) ) {
+			if ( $wp_version === $failure_data['current'] && str_contains( $offered_ver, '.1.next.minor' ) ) {
 				return false;
 			}
 
diff --git a/wp-admin/includes/class-custom-image-header.php b/wp-admin/includes/class-custom-image-header.php
index 582afd3cfd..f1361440fa 100644
--- a/wp-admin/includes/class-custom-image-header.php
+++ b/wp-admin/includes/class-custom-image-header.php
@@ -369,7 +369,7 @@ class Custom_Image_Header {
 		$default_color = '';
 		if ( current_theme_supports( 'custom-header', 'default-text-color' ) ) {
 			$default_color = get_theme_support( 'custom-header', 'default-text-color' );
-			if ( $default_color && false === strpos( $default_color, '#' ) ) {
+			if ( $default_color && ! str_contains( $default_color, '#' ) ) {
 				$default_color = '#' . $default_color;
 			}
 		}
@@ -768,7 +768,7 @@ class Custom_Image_Header {
 			$default_color = '';
 			if ( current_theme_supports( 'custom-header', 'default-text-color' ) ) {
 				$default_color = get_theme_support( 'custom-header', 'default-text-color' );
-				if ( $default_color && false === strpos( $default_color, '#' ) ) {
+				if ( $default_color && ! str_contains( $default_color, '#' ) ) {
 					$default_color = '#' . $default_color;
 				}
 			}
@@ -776,7 +776,7 @@ class Custom_Image_Header {
 			$default_color_attr = $default_color ? ' data-default-color="' . esc_attr( $default_color ) . '"' : '';
 
 			$header_textcolor = display_header_text() ? get_header_textcolor() : get_theme_support( 'custom-header', 'default-text-color' );
-			if ( $header_textcolor && false === strpos( $header_textcolor, '#' ) ) {
+			if ( $header_textcolor && ! str_contains( $header_textcolor, '#' ) ) {
 				$header_textcolor = '#' . $header_textcolor;
 			}
 
diff --git a/wp-admin/includes/class-ftp.php b/wp-admin/includes/class-ftp.php
index 07cb936de1..7658a0bc96 100644
--- a/wp-admin/includes/class-ftp.php
+++ b/wp-admin/includes/class-ftp.php
@@ -797,7 +797,7 @@ class ftp_base {
 		$chunks=explode(';',$pattern);
 		foreach($chunks as $pattern) {
 			$escape=array('$','^','.','{','}','(',')','[',']','|');
-			while(strpos($pattern,'**')!==false)
+			while(str_contains($pattern,'**'))
 				$pattern=str_replace('**','*',$pattern);
 			foreach($escape as $probe)
 				$pattern=str_replace($probe,"\\$probe",$pattern);
diff --git a/wp-admin/includes/class-wp-ajax-upgrader-skin.php b/wp-admin/includes/class-wp-ajax-upgrader-skin.php
index a3b2f9aaef..1ac8e31b43 100644
--- a/wp-admin/includes/class-wp-ajax-upgrader-skin.php
+++ b/wp-admin/includes/class-wp-ajax-upgrader-skin.php
@@ -118,7 +118,7 @@ class WP_Ajax_Upgrader_Skin extends Automatic_Upgrader_Skin {
 				$string = $this->upgrader->strings[ $string ];
 			}
 
-			if ( false !== strpos( $string, '%' ) ) {
+			if ( str_contains( $string, '%' ) ) {
 				if ( ! empty( $args ) ) {
 					$string = vsprintf( $string, $args );
 				}
diff --git a/wp-admin/includes/class-wp-automatic-updater.php b/wp-admin/includes/class-wp-automatic-updater.php
index 42b9c96508..b782898950 100644
--- a/wp-admin/includes/class-wp-automatic-updater.php
+++ b/wp-admin/includes/class-wp-automatic-updater.php
@@ -582,7 +582,7 @@ class WP_Automatic_Updater {
 
 		// Send debugging email to admin for all development installations.
 		if ( ! empty( $this->update_results ) ) {
-			$development_version = false !== strpos( get_bloginfo( 'version' ), '-' );
+			$development_version = str_contains( get_bloginfo( 'version' ), '-' );
 
 			/**
 			 * Filters whether to send a debugging email for each automatic background update.
@@ -640,13 +640,13 @@ class WP_Automatic_Updater {
 		// Any of these WP_Error codes are critical failures, as in they occurred after we started to copy core files.
 		// We should not try to perform a background update again until there is a successful one-click update performed by the user.
 		$critical = false;
-		if ( 'disk_full' === $error_code || false !== strpos( $error_code, '__copy_dir' ) ) {
+		if ( 'disk_full' === $error_code || str_contains( $error_code, '__copy_dir' ) ) {
 			$critical = true;
 		} elseif ( 'rollback_was_required' === $error_code && is_wp_error( $result->get_error_data()->rollback ) ) {
 			// A rollback is only critical if it failed too.
 			$critical        = true;
 			$rollback_result = $result->get_error_data()->rollback;
-		} elseif ( false !== strpos( $error_code, 'do_rollback' ) ) {
+		} elseif ( str_contains( $error_code, 'do_rollback' ) ) {
 			$critical = true;
 		}
 
diff --git a/wp-admin/includes/class-wp-ms-sites-list-table.php b/wp-admin/includes/class-wp-ms-sites-list-table.php
index 1359687235..4e54862185 100644
--- a/wp-admin/includes/class-wp-ms-sites-list-table.php
+++ b/wp-admin/includes/class-wp-ms-sites-list-table.php
@@ -81,7 +81,7 @@ class WP_MS_Sites_List_Table extends WP_List_Table {
 
 		$s    = isset( $_REQUEST['s'] ) ? wp_unslash( trim( $_REQUEST['s'] ) ) : '';
 		$wild = '';
-		if ( false !== strpos( $s, '*' ) ) {
+		if ( str_contains( $s, '*' ) ) {
 			$wild = '*';
 			$s    = trim( $s, '*' );
 		}
diff --git a/wp-admin/includes/class-wp-plugin-install-list-table.php b/wp-admin/includes/class-wp-plugin-install-list-table.php
index 7aa8df975b..0a1efba9ca 100644
--- a/wp-admin/includes/class-wp-plugin-install-list-table.php
+++ b/wp-admin/includes/class-wp-plugin-install-list-table.php
@@ -105,7 +105,7 @@ class WP_Plugin_Install_List_Table extends WP_List_Table {
 			$tabs['search'] = __( 'Search Results' );
 		}
 
-		if ( 'beta' === $tab || false !== strpos( get_bloginfo( 'version' ), '-' ) ) {
+		if ( 'beta' === $tab || str_contains( get_bloginfo( 'version' ), '-' ) ) {
 			$tabs['beta'] = _x( 'Beta Testing', 'Plugin Installer' );
 		}
 
diff --git a/wp-admin/includes/class-wp-site-health-auto-updates.php b/wp-admin/includes/class-wp-site-health-auto-updates.php
index 541bbd1f23..15b382ceb8 100644
--- a/wp-admin/includes/class-wp-site-health-auto-updates.php
+++ b/wp-admin/includes/class-wp-site-health-auto-updates.php
@@ -332,7 +332,7 @@ class WP_Site_Health_Auto_Updates {
 		}
 
 		$checksums = get_core_checksums( $wp_version, 'en_US' );
-		$dev       = ( false !== strpos( $wp_version, '-' ) );
+		$dev       = ( str_contains( $wp_version, '-' ) );
 		// Get the last stable version's files and test against that.
 		if ( ! $checksums && $dev ) {
 			$checksums = get_core_checksums( (float) $wp_version - 0.1, 'en_US' );
@@ -396,7 +396,7 @@ class WP_Site_Health_Auto_Updates {
 	public function test_accepts_dev_updates() {
 		require ABSPATH . WPINC . '/version.php'; // $wp_version; // x.y.z
 		// Only for dev versions.
-		if ( false === strpos( $wp_version, '-' ) ) {
+		if ( ! str_contains( $wp_version, '-' ) ) {
 			return false;
 		}
 
diff --git a/wp-admin/includes/class-wp-site-health.php b/wp-admin/includes/class-wp-site-health.php
index 2a91be3f60..4631f98d10 100644
--- a/wp-admin/includes/class-wp-site-health.php
+++ b/wp-admin/includes/class-wp-site-health.php
@@ -1366,7 +1366,7 @@ class WP_Site_Health {
 		 * libmysql has supported utf8mb4 since 5.5.3, same as the MySQL server.
 		 * mysqlnd has supported utf8mb4 since 5.0.9.
 		 */
-		if ( false !== strpos( $mysql_client_version, 'mysqlnd' ) ) {
+		if ( str_contains( $mysql_client_version, 'mysqlnd' ) ) {
 			$mysql_client_version = preg_replace( '/^\D+([\d.]+).*/', '$1', $mysql_client_version );
 			if ( version_compare( $mysql_client_version, '5.0.9', '<' ) ) {
 				$result['status'] = 'recommended';
@@ -3335,7 +3335,7 @@ class WP_Site_Health {
 	public function get_page_cache_headers() {
 
 		$cache_hit_callback = static function ( $header_value ) {
-			return false !== strpos( strtolower( $header_value ), 'hit' );
+			return str_contains( strtolower( $header_value ), 'hit' );
 		};
 
 		$cache_headers = array(
diff --git a/wp-admin/includes/class-wp-upgrader-skin.php b/wp-admin/includes/class-wp-upgrader-skin.php
index c7be61d951..598724f61c 100644
--- a/wp-admin/includes/class-wp-upgrader-skin.php
+++ b/wp-admin/includes/class-wp-upgrader-skin.php
@@ -197,7 +197,7 @@ class WP_Upgrader_Skin {
 			$feedback = $this->upgrader->strings[ $feedback ];
 		}
 
-		if ( strpos( $feedback, '%' ) !== false ) {
+		if ( str_contains( $feedback, '%' ) ) {
 			if ( $args ) {
 				$args     = array_map( 'strip_tags', $args );
 				$args     = array_map( 'esc_html', $args );
diff --git a/wp-admin/includes/credits.php b/wp-admin/includes/credits.php
index 5af26f2f42..907ee93c0b 100644
--- a/wp-admin/includes/credits.php
+++ b/wp-admin/includes/credits.php
@@ -32,7 +32,7 @@ function wp_credits( $version = '', $locale = '' ) {
 	$results = get_site_transient( 'wordpress_credits_' . $locale );
 
 	if ( ! is_array( $results )
-		|| false !== strpos( $version, '-' )
+		|| str_contains( $version, '-' )
 		|| ( isset( $results['data']['version'] ) && ! str_starts_with( $version, $results['data']['version'] ) )
 	) {
 		$url     = "http://api.wordpress.org/core/credits/1.1/?version={$version}&locale={$locale}";
diff --git a/wp-admin/includes/deprecated.php b/wp-admin/includes/deprecated.php
index 04f7208422..63aa7f7fa0 100644
--- a/wp-admin/includes/deprecated.php
+++ b/wp-admin/includes/deprecated.php
@@ -1376,7 +1376,7 @@ function wp_dashboard_plugins_output( $rss, $args = array() ) {
 		}
 
 		// Eliminate some common badly formed plugin descriptions.
-		while ( ( null !== $item_key = array_rand($items) ) && false !== strpos( $items[$item_key]->get_description(), 'Plugin Name:' ) )
+		while ( ( null !== $item_key = array_rand($items) ) && str_contains( $items[$item_key]->get_description(), 'Plugin Name:' ) )
 			unset($items[$item_key]);
 
 		if ( !isset($items[$item_key]) )
diff --git a/wp-admin/includes/file.php b/wp-admin/includes/file.php
index caa71d325b..562fece43e 100644
--- a/wp-admin/includes/file.php
+++ b/wp-admin/includes/file.php
@@ -1693,7 +1693,7 @@ function _unzip_file_ziparchive( $file, $to, $needed_dirs = array() ) {
 			continue;
 		}
 
-		if ( strpos( $dir, $to ) === false ) { // If the directory is not within the working directory, skip it.
+		if ( ! str_contains( $dir, $to ) ) { // If the directory is not within the working directory, skip it.
 			continue;
 		}
 
@@ -1834,7 +1834,7 @@ function _unzip_file_pclzip( $file, $to, $needed_dirs = array() ) {
 			continue;
 		}
 
-		if ( strpos( $dir, $to ) === false ) { // If the directory is not within the working directory, skip it.
+		if ( ! str_contains( $dir, $to ) ) { // If the directory is not within the working directory, skip it.
 			continue;
 		}
 
diff --git a/wp-admin/includes/media.php b/wp-admin/includes/media.php
index ea3c856782..8313c0235d 100644
--- a/wp-admin/includes/media.php
+++ b/wp-admin/includes/media.php
@@ -2183,8 +2183,8 @@ function media_upload_form( $errors = null ) {
 	 */
 	if (
 		wp_is_mobile() &&
-		strpos( $_SERVER['HTTP_USER_AGENT'], 'OS 7_' ) !== false &&
-		strpos( $_SERVER['HTTP_USER_AGENT'], 'like Mac OS X' ) !== false
+		str_contains( $_SERVER['HTTP_USER_AGENT'], 'OS 7_' ) &&
+		str_contains( $_SERVER['HTTP_USER_AGENT'], 'like Mac OS X' )
 	) {
 		$plupload_init['multi_selection'] = false;
 	}
@@ -3850,7 +3850,7 @@ function wp_media_attach_action( $parent_id, $action = 'attach' ) {
 		$referer  = wp_get_referer();
 
 		if ( $referer ) {
-			if ( false !== strpos( $referer, 'upload.php' ) ) {
+			if ( str_contains( $referer, 'upload.php' ) ) {
 				$location = remove_query_arg( array( 'attached', 'detach' ), $referer );
 			}
 		}
diff --git a/wp-admin/includes/misc.php b/wp-admin/includes/misc.php
index 1493e0e998..7922e8c270 100644
--- a/wp-admin/includes/misc.php
+++ b/wp-admin/includes/misc.php
@@ -76,7 +76,7 @@ function extract_from_markers( $filename, $marker ) {
 	$state = false;
 
 	foreach ( $markerdata as $markerline ) {
-		if ( false !== strpos( $markerline, '# END ' . $marker ) ) {
+		if ( str_contains( $markerline, '# END ' . $marker ) ) {
 			$state = false;
 		}
 
@@ -88,7 +88,7 @@ function extract_from_markers( $filename, $marker ) {
 			$result[] = $markerline;
 		}
 
-		if ( false !== strpos( $markerline, '# BEGIN ' . $marker ) ) {
+		if ( str_contains( $markerline, '# BEGIN ' . $marker ) ) {
 			$state = true;
 		}
 	}
@@ -194,10 +194,10 @@ Any changes to the directives between these markers will be overwritten.'
 	$found_end_marker = false;
 
 	foreach ( $lines as $line ) {
-		if ( ! $found_marker && false !== strpos( $line, $start_marker ) ) {
+		if ( ! $found_marker && str_contains( $line, $start_marker ) ) {
 			$found_marker = true;
 			continue;
-		} elseif ( ! $found_end_marker && false !== strpos( $line, $end_marker ) ) {
+		} elseif ( ! $found_end_marker && str_contains( $line, $end_marker ) ) {
 			$found_end_marker = true;
 			continue;
 		}
diff --git a/wp-admin/includes/plugin.php b/wp-admin/includes/plugin.php
index 3084312da5..49b574ec4b 100644
--- a/wp-admin/includes/plugin.php
+++ b/wp-admin/includes/plugin.php
@@ -102,7 +102,7 @@ function get_plugin_data( $plugin_file, $markup = true, $translate = true ) {
 	// If no text domain is defined fall back to the plugin slug.
 	if ( ! $plugin_data['TextDomain'] ) {
 		$plugin_slug = dirname( plugin_basename( $plugin_file ) );
-		if ( '.' !== $plugin_slug && false === strpos( $plugin_slug, '/' ) ) {
+		if ( '.' !== $plugin_slug && ! str_contains( $plugin_slug, '/' ) ) {
 			$plugin_data['TextDomain'] = $plugin_slug;
 		}
 	}
@@ -1935,7 +1935,7 @@ function get_admin_page_parent( $parent_page = '' ) {
 				$parent_file = $parent_page;
 				return $parent_page;
 			} elseif ( empty( $typenow ) && $pagenow === $submenu_array[2]
-				&& ( empty( $parent_file ) || false === strpos( $parent_file, '?' ) )
+				&& ( empty( $parent_file ) || ! str_contains( $parent_file, '?' ) )
 			) {
 				$parent_file = $parent_page;
 				return $parent_page;
diff --git a/wp-admin/includes/post.php b/wp-admin/includes/post.php
index 93cd9a7db5..70f792f5f1 100644
--- a/wp-admin/includes/post.php
+++ b/wp-admin/includes/post.php
@@ -1125,7 +1125,7 @@ function _fix_attachment_links( $post ) {
 		$url_id = (int) $url_match[2];
 		$rel_id = (int) $rel_match[1];
 
-		if ( ! $url_id || ! $rel_id || $url_id != $rel_id || strpos( $url_match[0], $site_url ) === false ) {
+		if ( ! $url_id || ! $rel_id || $url_id != $rel_id || ! str_contains( $url_match[0], $site_url ) ) {
 			continue;
 		}
 
@@ -1515,7 +1515,7 @@ function get_sample_permalink_html( $post, $new_title = null, $new_slug = null )
 	}
 
 	// Permalinks without a post/page name placeholder don't have anything to edit.
-	if ( false === strpos( $permalink, '%postname%' ) && false === strpos( $permalink, '%pagename%' ) ) {
+	if ( ! str_contains( $permalink, '%postname%' ) && ! str_contains( $permalink, '%pagename%' ) ) {
 		$return = '<strong>' . __( 'Permalink:' ) . "</strong>\n";
 
 		if ( false !== $view_link ) {
@@ -1755,7 +1755,7 @@ function _admin_notice_post_locked() {
 	}
 
 	$sendback = wp_get_referer();
-	if ( $locked && $sendback && false === strpos( $sendback, 'post.php' ) && false === strpos( $sendback, 'post-new.php' ) ) {
+	if ( $locked && $sendback && ! str_contains( $sendback, 'post.php' ) && ! str_contains( $sendback, 'post-new.php' ) ) {
 
 		$sendback_text = __( 'Go back' );
 	} else {
diff --git a/wp-admin/includes/privacy-tools.php b/wp-admin/includes/privacy-tools.php
index 0c38c71ef0..c5d7c9a97f 100644
--- a/wp-admin/includes/privacy-tools.php
+++ b/wp-admin/includes/privacy-tools.php
@@ -275,7 +275,7 @@ function wp_privacy_generate_personal_data_export_group_html( $group_data, $grou
 		foreach ( (array) $group_item_data as $group_item_datum ) {
 			$value = $group_item_datum['value'];
 			// If it looks like a link, make it a link.
-			if ( false === strpos( $value, ' ' ) && ( str_starts_with( $value, 'http://' ) || str_starts_with( $value, 'https://' ) ) ) {
+			if ( ! str_contains( $value, ' ' ) && ( str_starts_with( $value, 'http://' ) || str_starts_with( $value, 'https://' ) ) ) {
 				$value = '<a href="' . esc_url( $value ) . '">' . esc_html( $value ) . '</a>';
 			}
 
diff --git a/wp-admin/includes/template.php b/wp-admin/includes/template.php
index da8c363571..791fe8253a 100644
--- a/wp-admin/includes/template.php
+++ b/wp-admin/includes/template.php
@@ -1240,7 +1240,7 @@ function _get_plugin_from_callback( $callback ) {
 	try {
 		if ( is_array( $callback ) ) {
 			$reflection = new ReflectionMethod( $callback[0], $callback[1] );
-		} elseif ( is_string( $callback ) && false !== strpos( $callback, '::' ) ) {
+		} elseif ( is_string( $callback ) && str_contains( $callback, '::' ) ) {
 			$reflection = new ReflectionMethod( $callback );
 		} else {
 			$reflection = new ReflectionFunction( $callback );
diff --git a/wp-admin/includes/update-core.php b/wp-admin/includes/update-core.php
index 3c3510c6d6..506836ed5b 100644
--- a/wp-admin/includes/update-core.php
+++ b/wp-admin/includes/update-core.php
@@ -1140,7 +1140,7 @@ function update_core( $from, $to ) {
 	$php_version       = PHP_VERSION;
 	$mysql_version     = $wpdb->db_version();
 	$old_wp_version    = $GLOBALS['wp_version']; // The version of WordPress we're updating from.
-	$development_build = ( false !== strpos( $old_wp_version . $wp_version, '-' ) ); // A dash in the version indicates a development release.
+	$development_build = ( str_contains( $old_wp_version . $wp_version, '-' ) ); // A dash in the version indicates a development release.
 	$php_compat        = version_compare( $php_version, $required_php_version, '>=' );
 
 	if ( file_exists( WP_CONTENT_DIR . '/db.php' ) && empty( $wpdb->is_mysql ) ) {
@@ -1764,7 +1764,7 @@ function _upgrade_422_find_genericons_files_in_folder( $directory ) {
 	$files     = array();
 
 	if ( file_exists( "{$directory}example.html" )
-		&& false !== strpos( file_get_contents( "{$directory}example.html" ), '<title>Genericons</title>' )
+		&& str_contains( file_get_contents( "{$directory}example.html" ), '<title>Genericons</title>' )
 	) {
 		$files[] = "{$directory}example.html";
 	}
@@ -1774,7 +1774,7 @@ function _upgrade_422_find_genericons_files_in_folder( $directory ) {
 		$dirs,
 		static function( $dir ) {
 			// Skip any node_modules directories.
-			return false === strpos( $dir, 'node_modules' );
+			return ! str_contains( $dir, 'node_modules' );
 		}
 	);
 
diff --git a/wp-admin/includes/upgrade.php b/wp-admin/includes/upgrade.php
index 9ef205ed0f..dd31820057 100644
--- a/wp-admin/includes/upgrade.php
+++ b/wp-admin/includes/upgrade.php
@@ -1842,7 +1842,7 @@ function upgrade_350() {
 	if ( $wp_current_db_version < 21811 && wp_should_upgrade_global_tables() ) {
 		$meta_keys = array();
 		foreach ( array_merge( get_post_types(), get_taxonomies() ) as $name ) {
-			if ( false !== strpos( $name, '-' ) ) {
+			if ( str_contains( $name, '-' ) ) {
 				$meta_keys[] = 'edit_' . str_replace( '-', '_', $name ) . '_per_page';
 			}
 		}
@@ -3247,7 +3247,7 @@ function make_site_theme_from_oldschool( $theme_name, $template ) {
 		// Check to make sure it's not a new index.
 		if ( 'index.php' === $oldfile ) {
 			$index = implode( '', file( "$oldpath/$oldfile" ) );
-			if ( strpos( $index, 'WP_USE_THEMES' ) !== false ) {
+			if ( str_contains( $index, 'WP_USE_THEMES' ) ) {
 				if ( ! copy( "$default_dir/$oldfile", "$site_dir/$newfile" ) ) {
 					return false;
 				}
@@ -3364,7 +3364,7 @@ function make_site_theme_from_default( $theme_name, $template ) {
 
 		foreach ( $stylelines as $line ) {
 			foreach ( $headers as $header => $value ) {
-				if ( strpos( $line, $header ) !== false ) {
+				if ( str_contains( $line, $header ) ) {
 					$line = $header . ' ' . $value;
 					break;
 				}
diff --git a/wp-admin/includes/user.php b/wp-admin/includes/user.php
index 47458553d7..1d2d919348 100644
--- a/wp-admin/includes/user.php
+++ b/wp-admin/includes/user.php
@@ -174,7 +174,7 @@ function edit_user( $user_id = 0 ) {
 	}
 
 	// Check for "\" in password.
-	if ( false !== strpos( wp_unslash( $pass1 ), '\\' ) ) {
+	if ( str_contains( wp_unslash( $pass1 ), '\\' ) ) {
 		$errors->add( 'pass', __( '<strong>Error:</strong> Passwords may not contain the character "\\".' ), array( 'form-field' => 'pass1' ) );
 	}
 
diff --git a/wp-admin/menu-header.php b/wp-admin/menu-header.php
index 290d6d1813..8409ced14c 100644
--- a/wp-admin/menu-header.php
+++ b/wp-admin/menu-header.php
@@ -112,7 +112,7 @@ function _wp_menu_output( $menu, $submenu, $submenu_as_parent = true ) {
 		$img_style = '';
 		$img_class = ' dashicons-before';
 
-		if ( false !== strpos( $class, 'wp-menu-separator' ) ) {
+		if ( str_contains( $class, 'wp-menu-separator' ) ) {
 			$is_separator = true;
 		}
 
diff --git a/wp-admin/network/site-settings.php b/wp-admin/network/site-settings.php
index 7425c1bb8f..c8cef03466 100644
--- a/wp-admin/network/site-settings.php
+++ b/wp-admin/network/site-settings.php
@@ -143,7 +143,7 @@ if ( ! empty( $messages ) ) {
 				}
 			}
 
-			if ( strpos( $option->option_value, "\n" ) !== false ) {
+			if ( str_contains( $option->option_value, "\n" ) ) {
 				?>
 				<tr class="form-field">
 					<th scope="row"><label for="<?php echo esc_attr( $option->option_name ); ?>" class="code"><?php echo esc_html( $option->option_name ); ?></label></th>
diff --git a/wp-admin/network/themes.php b/wp-admin/network/themes.php
index 86747337d5..1ad21e9738 100644
--- a/wp-admin/network/themes.php
+++ b/wp-admin/network/themes.php
@@ -39,7 +39,7 @@ if ( $action ) {
 		case 'enable':
 			check_admin_referer( 'enable-theme_' . $_GET['theme'] );
 			WP_Theme::network_enable_theme( $_GET['theme'] );
-			if ( false === strpos( $referer, '/network/themes.php' ) ) {
+			if ( ! str_contains( $referer, '/network/themes.php' ) ) {
 				wp_redirect( network_admin_url( 'themes.php?enabled=1' ) );
 			} else {
 				wp_safe_redirect( add_query_arg( 'enabled', 1, $referer ) );
diff --git a/wp-admin/options-general.php b/wp-admin/options-general.php
index 5642b461be..58ef903608 100644
--- a/wp-admin/options-general.php
+++ b/wp-admin/options-general.php
@@ -236,7 +236,7 @@ $tzstring       = get_option( 'timezone_string' );
 $check_zone_info = true;
 
 // Remove old Etc mappings. Fallback to gmt_offset.
-if ( false !== strpos( $tzstring, 'Etc/GMT' ) ) {
+if ( str_contains( $tzstring, 'Etc/GMT' ) ) {
 	$tzstring = '';
 }
 
diff --git a/wp-admin/options.php b/wp-admin/options.php
index d434e7b974..df872f4731 100644
--- a/wp-admin/options.php
+++ b/wp-admin/options.php
@@ -400,7 +400,7 @@ foreach ( (array) $options as $option ) :
 <tr>
 	<th scope="row"><label for="<?php echo $name; ?>"><?php echo esc_html( $option->option_name ); ?></label></th>
 <td>
-	<?php if ( strpos( $value, "\n" ) !== false ) : ?>
+	<?php if ( str_contains( $value, "\n" ) ) : ?>
 		<textarea class="<?php echo $class; ?>" name="<?php echo $name; ?>" id="<?php echo $name; ?>" cols="30" rows="5"><?php echo esc_textarea( $value ); ?></textarea>
 	<?php else : ?>
 		<input class="regular-text <?php echo $class; ?>" type="text" name="<?php echo $name; ?>" id="<?php echo $name; ?>" value="<?php echo esc_attr( $value ); ?>"<?php disabled( $disabled, true ); ?> />
diff --git a/wp-admin/post.php b/wp-admin/post.php
index 95a63dfa27..17875cb3e5 100644
--- a/wp-admin/post.php
+++ b/wp-admin/post.php
@@ -55,8 +55,8 @@ if ( isset( $_POST['deletepost'] ) ) {
 
 $sendback = wp_get_referer();
 if ( ! $sendback ||
-	false !== strpos( $sendback, 'post.php' ) ||
-	false !== strpos( $sendback, 'post-new.php' ) ) {
+	str_contains( $sendback, 'post.php' ) ||
+	str_contains( $sendback, 'post-new.php' ) ) {
 	if ( 'attachment' === $post_type ) {
 		$sendback = admin_url( 'upload.php' );
 	} else {
@@ -97,7 +97,7 @@ switch ( $action ) {
 		$_POST['ping_status']    = get_default_comment_status( $post->post_type, 'pingback' );
 
 		// Wrap Quick Draft content in the Paragraph block.
-		if ( false === strpos( $_POST['content'], '<!-- wp:paragraph -->' ) ) {
+		if ( ! str_contains( $_POST['content'], '<!-- wp:paragraph -->' ) ) {
 			$_POST['content'] = sprintf(
 				'<!-- wp:paragraph -->%s<!-- /wp:paragraph -->',
 				str_replace( array( "\r\n", "\r", "\n" ), '<br />', $_POST['content'] )
diff --git a/wp-admin/upload.php b/wp-admin/upload.php
index 08c6241107..29a8c4de8d 100644
--- a/wp-admin/upload.php
+++ b/wp-admin/upload.php
@@ -263,7 +263,7 @@ if ( $doaction ) {
 	$location = 'upload.php';
 	$referer  = wp_get_referer();
 	if ( $referer ) {
-		if ( false !== strpos( $referer, 'upload.php' ) ) {
+		if ( str_contains( $referer, 'upload.php' ) ) {
 			$location = remove_query_arg( array( 'trashed', 'untrashed', 'deleted', 'message', 'ids', 'posted' ), $referer );
 		}
 	}
diff --git a/wp-admin/user-edit.php b/wp-admin/user-edit.php
index d17574ce76..dd7309cac0 100644
--- a/wp-admin/user-edit.php
+++ b/wp-admin/user-edit.php
@@ -211,7 +211,7 @@ switch ( $action ) {
 				<?php else : ?>
 					<p><strong><?php _e( 'User updated.' ); ?></strong></p>
 				<?php endif; ?>
-				<?php if ( $wp_http_referer && false === strpos( $wp_http_referer, 'user-new.php' ) && ! IS_PROFILE_PAGE ) : ?>
+				<?php if ( $wp_http_referer && ! str_contains( $wp_http_referer, 'user-new.php' ) && ! IS_PROFILE_PAGE ) : ?>
 					<p><a href="<?php echo esc_url( wp_validate_redirect( sanitize_url( $wp_http_referer ), self_admin_url( 'users.php' ) ) ); ?>"><?php _e( '&larr; Go to Users' ); ?></a></p>
 				<?php endif; ?>
 			</div>
diff --git a/wp-admin/user-new.php b/wp-admin/user-new.php
index a1bf974237..5c8f71c311 100644
--- a/wp-admin/user-new.php
+++ b/wp-admin/user-new.php
@@ -34,7 +34,7 @@ if ( isset( $_REQUEST['action'] ) && 'adduser' === $_REQUEST['action'] ) {
 
 	$user_details = null;
 	$user_email   = wp_unslash( $_REQUEST['email'] );
-	if ( false !== strpos( $user_email, '@' ) ) {
+	if ( str_contains( $user_email, '@' ) ) {
 		$user_details = get_user_by( 'email', $user_email );
 	} else {
 		if ( current_user_can( 'manage_network_users' ) ) {
diff --git a/wp-admin/widgets-form.php b/wp-admin/widgets-form.php
index e6f4fc3979..4b544b6342 100644
--- a/wp-admin/widgets-form.php
+++ b/wp-admin/widgets-form.php
@@ -450,7 +450,7 @@ do_action( 'widgets_admin_page' );
 
 $theme_sidebars = array();
 foreach ( $wp_registered_sidebars as $sidebar => $registered_sidebar ) {
-	if ( false !== strpos( $registered_sidebar['class'], 'inactive-sidebar' ) || 'orphaned_widgets' === substr( $sidebar, 0, 16 ) ) {
+	if ( str_contains( $registered_sidebar['class'], 'inactive-sidebar' ) || 'orphaned_widgets' === substr( $sidebar, 0, 16 ) ) {
 		$wrap_class = 'widgets-holder-wrap';
 		if ( ! empty( $registered_sidebar['class'] ) ) {
 			$wrap_class .= ' ' . $registered_sidebar['class'];
diff --git a/wp-content/themes/twentyseventeen/inc/icon-functions.php b/wp-content/themes/twentyseventeen/inc/icon-functions.php
index 82a1ebedcc..b25428fb1d 100644
--- a/wp-content/themes/twentyseventeen/inc/icon-functions.php
+++ b/wp-content/themes/twentyseventeen/inc/icon-functions.php
@@ -130,7 +130,7 @@ function twentyseventeen_nav_menu_social_icons( $item_output, $item, $depth, $ar
 	// Change SVG icon inside social links menu if there is supported URL.
 	if ( 'social' === $args->theme_location ) {
 		foreach ( $social_icons as $attr => $value ) {
-			if ( false !== strpos( $item_output, $attr ) ) {
+			if ( str_contains( $item_output, $attr ) ) {
 				$item_output = str_replace( $args->link_after, '</span>' . twentyseventeen_get_svg( array( 'icon' => esc_attr( $value ) ) ), $item_output );
 			}
 		}
diff --git a/wp-content/themes/twentyseventeen/template-parts/post/content-audio.php b/wp-content/themes/twentyseventeen/template-parts/post/content-audio.php
index eea60e6c7c..d50ce9f66a 100644
--- a/wp-content/themes/twentyseventeen/template-parts/post/content-audio.php
+++ b/wp-content/themes/twentyseventeen/template-parts/post/content-audio.php
@@ -46,7 +46,7 @@
 		$audio   = false;
 
 		// Only get audio from the content if a playlist isn't present.
-	if ( false === strpos( $content, 'wp-playlist-script' ) ) {
+	if ( ! str_contains( $content, 'wp-playlist-script' ) ) {
 		$audio = get_media_embedded_in_content( $content, array( 'audio' ) );
 	}
 
diff --git a/wp-content/themes/twentyseventeen/template-parts/post/content-video.php b/wp-content/themes/twentyseventeen/template-parts/post/content-video.php
index fd7865db92..a5c387e767 100644
--- a/wp-content/themes/twentyseventeen/template-parts/post/content-video.php
+++ b/wp-content/themes/twentyseventeen/template-parts/post/content-video.php
@@ -46,7 +46,7 @@
 		$video   = false;
 
 		// Only get video from the content if a playlist isn't present.
-	if ( false === strpos( $content, 'wp-playlist-script' ) ) {
+	if ( ! str_contains( $content, 'wp-playlist-script' ) ) {
 		$video = get_media_embedded_in_content( $content, array( 'video', 'object', 'embed', 'iframe' ) );
 	}
 	?>
diff --git a/wp-content/themes/twentytwenty/comments.php b/wp-content/themes/twentytwenty/comments.php
index 91a3198eed..c4ef803cba 100644
--- a/wp-content/themes/twentytwenty/comments.php
+++ b/wp-content/themes/twentytwenty/comments.php
@@ -80,7 +80,7 @@ if ( $comments ) {
 				$pagination_classes = '';
 
 				// If we're only showing the "Next" link, add a class indicating so.
-				if ( false === strpos( $comment_pagination, 'prev page-numbers' ) ) {
+				if ( ! str_contains( $comment_pagination, 'prev page-numbers' ) ) {
 					$pagination_classes = ' only-next';
 				}
 				?>
diff --git a/wp-content/themes/twentytwenty/functions.php b/wp-content/themes/twentytwenty/functions.php
index 65085df485..9fd2818ae7 100644
--- a/wp-content/themes/twentytwenty/functions.php
+++ b/wp-content/themes/twentytwenty/functions.php
@@ -316,7 +316,7 @@ function twentytwenty_get_custom_logo( $html ) {
 			);
 
 			// Add a style attribute with the height, or append the height to the style attribute if the style attribute already exists.
-			if ( strpos( $html, ' style=' ) === false ) {
+			if ( ! str_contains( $html, ' style=' ) ) {
 				$search[]  = '/(src=)/';
 				$replace[] = "style=\"height: {$logo_height}px;\" src=";
 			} else {
diff --git a/wp-content/themes/twentytwenty/template-parts/pagination.php b/wp-content/themes/twentytwenty/template-parts/pagination.php
index 8973447ad6..036b6fd6f4 100644
--- a/wp-content/themes/twentytwenty/template-parts/pagination.php
+++ b/wp-content/themes/twentytwenty/template-parts/pagination.php
@@ -37,12 +37,12 @@ $posts_pagination = get_the_posts_pagination(
 );
 
 // If we're not outputting the previous page link, prepend a placeholder with `visibility: hidden` to take its place.
-if ( strpos( $posts_pagination, 'prev page-numbers' ) === false ) {
+if ( ! str_contains( $posts_pagination, 'prev page-numbers' ) ) {
 	$posts_pagination = str_replace( '<div class="nav-links">', '<div class="nav-links"><span class="prev page-numbers placeholder" aria-hidden="true">' . $prev_text . '</span>', $posts_pagination );
 }
 
 // If we're not outputting the next page link, append a placeholder with `visibility: hidden` to take its place.
-if ( strpos( $posts_pagination, 'next page-numbers' ) === false ) {
+if ( ! str_contains( $posts_pagination, 'next page-numbers' ) ) {
 	$posts_pagination = str_replace( '</div>', '<span class="next page-numbers placeholder" aria-hidden="true">' . $next_text . '</span></div>', $posts_pagination );
 }
 
diff --git a/wp-content/themes/twentytwentyone/inc/template-functions.php b/wp-content/themes/twentytwentyone/inc/template-functions.php
index d0d385d3ba..a862dfac14 100644
--- a/wp-content/themes/twentytwentyone/inc/template-functions.php
+++ b/wp-content/themes/twentytwentyone/inc/template-functions.php
@@ -445,7 +445,7 @@ function twenty_twenty_one_get_attachment_image_attributes( $attr, $attachment,
 		return $attr;
 	}
 
-	if ( isset( $attr['class'] ) && false !== strpos( $attr['class'], 'custom-logo' ) ) {
+	if ( isset( $attr['class'] ) && str_contains( $attr['class'], 'custom-logo' ) ) {
 		return $attr;
 	}
 
diff --git a/wp-includes/block-supports/duotone.php b/wp-includes/block-supports/duotone.php
index 489f9fdeb3..429eeee051 100644
--- a/wp-includes/block-supports/duotone.php
+++ b/wp-includes/block-supports/duotone.php
@@ -48,14 +48,14 @@
  * @return float Value in the range [0, 1].
  */
 function wp_tinycolor_bound01( $n, $max ) {
-	if ( 'string' === gettype( $n ) && false !== strpos( $n, '.' ) && 1 === (float) $n ) {
+	if ( 'string' === gettype( $n ) && str_contains( $n, '.' ) && 1 === (float) $n ) {
 		$n = '100%';
 	}
 
 	$n = min( $max, max( 0, (float) $n ) );
 
 	// Automatically convert percentage into number.
-	if ( 'string' === gettype( $n ) && false !== strpos( $n, '%' ) ) {
+	if ( 'string' === gettype( $n ) && str_contains( $n, '%' ) ) {
 		$n = (int) ( $n * $max ) / 100;
 	}
 
diff --git a/wp-includes/block-template.php b/wp-includes/block-template.php
index a65283cbe7..b3b1eecd49 100644
--- a/wp-includes/block-template.php
+++ b/wp-includes/block-template.php
@@ -166,7 +166,7 @@ function resolve_block_template( $template_type, $template_hierarchy, $fallback_
 	// Is the active theme a child theme, and is the PHP fallback template part of it?
 	if (
 		str_starts_with( $fallback_template, $theme_base_path ) &&
-		strpos( $fallback_template, $parent_theme_base_path ) === false
+		! str_contains( $fallback_template, $parent_theme_base_path )
 	) {
 		$fallback_template_slug = substr(
 			$fallback_template,
diff --git a/wp-includes/blocks.php b/wp-includes/blocks.php
index 729c789683..9b1884c660 100644
--- a/wp-includes/blocks.php
+++ b/wp-includes/blocks.php
@@ -583,7 +583,7 @@ function has_blocks( $post = null ) {
 		$post = $wp_post->post_content;
 	}
 
-	return false !== strpos( (string) $post, '<!-- wp:' );
+	return str_contains( (string) $post, '<!-- wp:' );
 }
 
 /**
@@ -619,12 +619,12 @@ function has_block( $block_name, $post = null ) {
 	 * This matches behavior for WordPress 5.0.0 - 5.3.0 in matching blocks by
 	 * their serialized names.
 	 */
-	if ( false === strpos( $block_name, '/' ) ) {
+	if ( ! str_contains( $block_name, '/' ) ) {
 		$block_name = 'core/' . $block_name;
 	}
 
 	// Test for existence of block by its fully qualified name.
-	$has_block = false !== strpos( $post, '<!-- wp:' . $block_name . ' ' );
+	$has_block = str_contains( $post, '<!-- wp:' . $block_name . ' ' );
 
 	if ( ! $has_block ) {
 		/*
@@ -633,7 +633,7 @@ function has_block( $block_name, $post = null ) {
 		 */
 		$serialized_block_name = strip_core_block_namespace( $block_name );
 		if ( $serialized_block_name !== $block_name ) {
-			$has_block = false !== strpos( $post, '<!-- wp:' . $serialized_block_name . ' ' );
+			$has_block = str_contains( $post, '<!-- wp:' . $serialized_block_name . ' ' );
 		}
 	}
 
diff --git a/wp-includes/canonical.php b/wp-includes/canonical.php
index a02ab793ce..0ce211327e 100644
--- a/wp-includes/canonical.php
+++ b/wp-includes/canonical.php
@@ -389,7 +389,7 @@ function redirect_canonical( $requested_url = null, $do_redirect = true ) {
 					}
 				}
 			}
-		} elseif ( is_single() && strpos( $wp_rewrite->permalink_structure, '%category%' ) !== false ) {
+		} elseif ( is_single() && str_contains( $wp_rewrite->permalink_structure, '%category%' ) ) {
 			$category_name = get_query_var( 'category_name' );
 
 			if ( $category_name ) {
@@ -518,7 +518,7 @@ function redirect_canonical( $requested_url = null, $do_redirect = true ) {
 
 			if ( ! empty( $addl_path )
 				&& $wp_rewrite->using_index_permalinks()
-				&& strpos( $redirect['path'], '/' . $wp_rewrite->index . '/' ) === false
+				&& ! str_contains( $redirect['path'], '/' . $wp_rewrite->index . '/' )
 			) {
 				$redirect['path'] = trailingslashit( $redirect['path'] ) . $wp_rewrite->index . '/';
 			}
@@ -737,7 +737,7 @@ function redirect_canonical( $requested_url = null, $do_redirect = true ) {
 	}
 
 	// Hex-encoded octets are case-insensitive.
-	if ( false !== strpos( $requested_url, '%' ) ) {
+	if ( str_contains( $requested_url, '%' ) ) {
 		if ( ! function_exists( 'lowercase_octets' ) ) {
 			/**
 			 * Converts the first hex-encoded octet match to lowercase.
diff --git a/wp-includes/class-wp-comment-query.php b/wp-includes/class-wp-comment-query.php
index cfdf05dbfd..40f2838966 100644
--- a/wp-includes/class-wp-comment-query.php
+++ b/wp-includes/class-wp-comment-query.php
@@ -677,7 +677,7 @@ class WP_Comment_Query {
 				// If no date-related order is available, use the date from the first available clause.
 				if ( ! $comment_id_order ) {
 					foreach ( $orderby_array as $orderby_clause ) {
-						if ( false !== strpos( 'ASC', $orderby_clause ) ) {
+						if ( str_contains( 'ASC', $orderby_clause ) ) {
 							$comment_id_order = 'ASC';
 						} else {
 							$comment_id_order = 'DESC';
diff --git a/wp-includes/class-wp-customize-manager.php b/wp-includes/class-wp-customize-manager.php
index cc78611982..ce85de9bd4 100644
--- a/wp-includes/class-wp-customize-manager.php
+++ b/wp-includes/class-wp-customize-manager.php
@@ -3610,7 +3610,7 @@ final class WP_Customize_Manager {
 		 */
 		$revisions = wp_get_post_revisions( $changeset_post_id, array( 'check_enabled' => false ) );
 		foreach ( $revisions as $revision ) {
-			if ( false !== strpos( $revision->post_name, "{$changeset_post_id}-autosave" ) ) {
+			if ( str_contains( $revision->post_name, "{$changeset_post_id}-autosave" ) ) {
 				$wpdb->update(
 					$wpdb->posts,
 					array(
diff --git a/wp-includes/class-wp-date-query.php b/wp-includes/class-wp-date-query.php
index eee508657d..7abb3216b5 100644
--- a/wp-includes/class-wp-date-query.php
+++ b/wp-includes/class-wp-date-query.php
@@ -494,7 +494,7 @@ class WP_Date_Query {
 		);
 
 		// Attempt to detect a table prefix.
-		if ( false === strpos( $column, '.' ) ) {
+		if ( ! str_contains( $column, '.' ) ) {
 			/**
 			 * Filters the list of valid date query columns.
 			 *
diff --git a/wp-includes/class-wp-editor.php b/wp-includes/class-wp-editor.php
index 8472de26ca..f7fd51905e 100644
--- a/wp-includes/class-wp-editor.php
+++ b/wp-includes/class-wp-editor.php
@@ -106,7 +106,7 @@ final class _WP_Editors {
 		self::$this_tinymce = ( $set['tinymce'] && user_can_richedit() );
 
 		if ( self::$this_tinymce ) {
-			if ( false !== strpos( $editor_id, '[' ) ) {
+			if ( str_contains( $editor_id, '[' ) ) {
 				self::$this_tinymce = false;
 				_deprecated_argument( 'wp_editor()', '3.9.0', 'TinyMCE editor IDs cannot have brackets.' );
 			}
@@ -1484,7 +1484,7 @@ final class _WP_Editors {
 				continue;
 			}
 
-			if ( false !== strpos( $value, '&' ) ) {
+			if ( str_contains( $value, '&' ) ) {
 				$mce_translation[ $key ] = html_entity_decode( $value, ENT_QUOTES, 'UTF-8' );
 			}
 		}
diff --git a/wp-includes/class-wp-http-proxy.php b/wp-includes/class-wp-http-proxy.php
index 0bc265862a..6ec091f2ba 100644
--- a/wp-includes/class-wp-http-proxy.php
+++ b/wp-includes/class-wp-http-proxy.php
@@ -209,7 +209,7 @@ class WP_HTTP_Proxy {
 		if ( null === $bypass_hosts ) {
 			$bypass_hosts = preg_split( '|,\s*|', WP_PROXY_BYPASS_HOSTS );
 
-			if ( false !== strpos( WP_PROXY_BYPASS_HOSTS, '*' ) ) {
+			if ( str_contains( WP_PROXY_BYPASS_HOSTS, '*' ) ) {
 				$wildcard_regex = array();
 				foreach ( $bypass_hosts as $host ) {
 					$wildcard_regex[] = str_replace( '\*', '.+', preg_quote( $host, '/' ) );
diff --git a/wp-includes/class-wp-http.php b/wp-includes/class-wp-http.php
index 446ce2be8e..e1d37878a1 100644
--- a/wp-includes/class-wp-http.php
+++ b/wp-includes/class-wp-http.php
@@ -721,7 +721,7 @@ class WP_Http {
 		 * In this case, determine the final HTTP header and parse from there.
 		 */
 		for ( $i = count( $headers ) - 1; $i >= 0; $i-- ) {
-			if ( ! empty( $headers[ $i ] ) && false === strpos( $headers[ $i ], ':' ) ) {
+			if ( ! empty( $headers[ $i ] ) && ! str_contains( $headers[ $i ], ':' ) ) {
 				$headers = array_splice( $headers, $i );
 				break;
 			}
@@ -734,7 +734,7 @@ class WP_Http {
 				continue;
 			}
 
-			if ( false === strpos( $tempheader, ':' ) ) {
+			if ( ! str_contains( $tempheader, ':' ) ) {
 				$stack   = explode( ' ', $tempheader, 3 );
 				$stack[] = '';
 				list( , $response['code'], $response['message']) = $stack;
@@ -905,7 +905,7 @@ class WP_Http {
 		if ( null === $accessible_hosts ) {
 			$accessible_hosts = preg_split( '|,\s*|', WP_ACCESSIBLE_HOSTS );
 
-			if ( false !== strpos( WP_ACCESSIBLE_HOSTS, '*' ) ) {
+			if ( str_contains( WP_ACCESSIBLE_HOSTS, '*' ) ) {
 				$wildcard_regex = array();
 				foreach ( $accessible_hosts as $host ) {
 					$wildcard_regex[] = str_replace( '\*', '.+', preg_quote( $host, '/' ) );
@@ -1096,7 +1096,7 @@ class WP_Http {
 			return 4;
 		}
 
-		if ( false !== strpos( $maybe_ip, ':' ) && preg_match( '/^(((?=.*(::))(?!.*\3.+\3))\3?|([\dA-F]{1,4}(\3|:\b|$)|\2))(?4){5}((?4){2}|(((2[0-4]|1\d|[1-9])?\d|25[0-5])\.?\b){4})$/i', trim( $maybe_ip, ' []' ) ) ) {
+		if ( str_contains( $maybe_ip, ':' ) && preg_match( '/^(((?=.*(::))(?!.*\3.+\3))\3?|([\dA-F]{1,4}(\3|:\b|$)|\2))(?4){5}((?4){2}|(((2[0-4]|1\d|[1-9])?\d|25[0-5])\.?\b){4})$/i', trim( $maybe_ip, ' []' ) ) ) {
 			return 6;
 		}
 
diff --git a/wp-includes/class-wp-meta-query.php b/wp-includes/class-wp-meta-query.php
index bab45d725b..0c6867d84e 100644
--- a/wp-includes/class-wp-meta-query.php
+++ b/wp-includes/class-wp-meta-query.php
@@ -374,7 +374,7 @@ class WP_Meta_Query {
 		 * If any JOINs are LEFT JOINs (as in the case of NOT EXISTS), then all JOINs should
 		 * be LEFT. Otherwise posts with no metadata will be excluded from results.
 		 */
-		if ( false !== strpos( $sql['join'], 'LEFT JOIN' ) ) {
+		if ( str_contains( $sql['join'], 'LEFT JOIN' ) ) {
 			$sql['join'] = str_replace( 'INNER JOIN', 'LEFT JOIN', $sql['join'] );
 		}
 
diff --git a/wp-includes/class-wp-oembed.php b/wp-includes/class-wp-oembed.php
index 8d47851599..efce9b3388 100644
--- a/wp-includes/class-wp-oembed.php
+++ b/wp-includes/class-wp-oembed.php
@@ -754,7 +754,7 @@ class WP_oEmbed {
 	 * @return string Possibly modified $html
 	 */
 	public function _strip_newlines( $html, $data, $url ) {
-		if ( false === strpos( $html, "\n" ) ) {
+		if ( ! str_contains( $html, "\n" ) ) {
 			return $html;
 		}
 
diff --git a/wp-includes/class-wp-post-type.php b/wp-includes/class-wp-post-type.php
index b7f8abb083..42b413254c 100644
--- a/wp-includes/class-wp-post-type.php
+++ b/wp-includes/class-wp-post-type.php
@@ -737,7 +737,7 @@ final class WP_Post_Type {
 			remove_rewrite_tag( "%$this->name%" );
 			remove_permastruct( $this->name );
 			foreach ( $wp_rewrite->extra_rules_top as $regex => $query ) {
-				if ( false !== strpos( $query, "index.php?post_type=$this->name" ) ) {
+				if ( str_contains( $query, "index.php?post_type=$this->name" ) ) {
 					unset( $wp_rewrite->extra_rules_top[ $regex ] );
 				}
 			}
diff --git a/wp-includes/class-wp-query.php b/wp-includes/class-wp-query.php
index e6e553c6ca..8afad87ec3 100644
--- a/wp-includes/class-wp-query.php
+++ b/wp-includes/class-wp-query.php
@@ -1015,7 +1015,7 @@ class WP_Query {
 			$this->is_admin = true;
 		}
 
-		if ( false !== strpos( $qv['feed'], 'comments-' ) ) {
+		if ( str_contains( $qv['feed'], 'comments-' ) ) {
 			$qv['feed']         = str_replace( 'comments-', '', $qv['feed'] );
 			$qv['withcomments'] = 1;
 		}
@@ -1185,7 +1185,7 @@ class WP_Query {
 					$term = implode( ',', $term );
 				}
 
-				if ( strpos( $term, '+' ) !== false ) {
+				if ( str_contains( $term, '+' ) ) {
 					$terms = preg_split( '/[+]+/', $term );
 					foreach ( $terms as $term ) {
 						$tax_query[] = array_merge(
@@ -1298,7 +1298,7 @@ class WP_Query {
 		// Tag stuff.
 
 		if ( '' !== $q['tag'] && ! $this->is_singular && $this->query_vars_changed ) {
-			if ( strpos( $q['tag'], ',' ) !== false ) {
+			if ( str_contains( $q['tag'], ',' ) ) {
 				$tags = preg_split( '/[,\r\n\t ]+/', $q['tag'] );
 				foreach ( (array) $tags as $tag ) {
 					$tag                 = sanitize_term_field( 'slug', $tag, 0, 'post_tag', 'db' );
@@ -2354,7 +2354,7 @@ class WP_Query {
 		// Author stuff for nice URLs.
 
 		if ( '' !== $q['author_name'] ) {
-			if ( strpos( $q['author_name'], '/' ) !== false ) {
+			if ( str_contains( $q['author_name'], '/' ) ) {
 				$q['author_name'] = explode( '/', $q['author_name'] );
 				if ( $q['author_name'][ count( $q['author_name'] ) - 1 ] ) {
 					$q['author_name'] = $q['author_name'][ count( $q['author_name'] ) - 1 ]; // No trailing slash.
@@ -4754,7 +4754,7 @@ class WP_Query {
 		}
 
 		$content = $post->post_content;
-		if ( false !== strpos( $content, '<!--nextpage-->' ) ) {
+		if ( str_contains( $content, '<!--nextpage-->' ) ) {
 			$content = str_replace( "\n<!--nextpage-->\n", '<!--nextpage-->', $content );
 			$content = str_replace( "\n<!--nextpage-->", '<!--nextpage-->', $content );
 			$content = str_replace( "<!--nextpage-->\n", '<!--nextpage-->', $content );
diff --git a/wp-includes/class-wp-rewrite.php b/wp-includes/class-wp-rewrite.php
index 1f42f838bc..35598c3d80 100644
--- a/wp-includes/class-wp-rewrite.php
+++ b/wp-includes/class-wp-rewrite.php
@@ -509,7 +509,7 @@ class WP_Rewrite {
 		$date_endian          = '';
 
 		foreach ( $endians as $endian ) {
-			if ( false !== strpos( $this->permalink_structure, $endian ) ) {
+			if ( str_contains( $this->permalink_structure, $endian ) ) {
 				$date_endian = $endian;
 				break;
 			}
@@ -1660,7 +1660,7 @@ class WP_Rewrite {
 			$external = false;
 			$query    = add_query_arg( $query, 'index.php' );
 		} else {
-			$index = false === strpos( $query, '?' ) ? strlen( $query ) : strpos( $query, '?' );
+			$index = ! str_contains( $query, '?' ) ? strlen( $query ) : strpos( $query, '?' );
 			$front = substr( $query, 0, $index );
 
 			$external = $front != $this->index;
diff --git a/wp-includes/class-wp-site-query.php b/wp-includes/class-wp-site-query.php
index 6435ac02e1..6598866162 100644
--- a/wp-includes/class-wp-site-query.php
+++ b/wp-includes/class-wp-site-query.php
@@ -753,7 +753,7 @@ class WP_Site_Query {
 	protected function get_search_sql( $search, $columns ) {
 		global $wpdb;
 
-		if ( false !== strpos( $search, '*' ) ) {
+		if ( str_contains( $search, '*' ) ) {
 			$like = '%' . implode( '%', array_map( array( $wpdb, 'esc_like' ), explode( '*', $search ) ) ) . '%';
 		} else {
 			$like = '%' . $wpdb->esc_like( $search ) . '%';
diff --git a/wp-includes/class-wp-user-query.php b/wp-includes/class-wp-user-query.php
index 60190ac838..4f56ca940e 100644
--- a/wp-includes/class-wp-user-query.php
+++ b/wp-includes/class-wp-user-query.php
@@ -713,7 +713,7 @@ class WP_User_Query {
 				$search_columns = array_intersect( $qv['search_columns'], array( 'ID', 'user_login', 'user_email', 'user_url', 'user_nicename', 'display_name' ) );
 			}
 			if ( ! $search_columns ) {
-				if ( false !== strpos( $search, '@' ) ) {
+				if ( str_contains( $search, '@' ) ) {
 					$search_columns = array( 'user_email' );
 				} elseif ( is_numeric( $search ) ) {
 					$search_columns = array( 'user_login', 'ID' );
diff --git a/wp-includes/class-wp-xmlrpc-server.php b/wp-includes/class-wp-xmlrpc-server.php
index 96961d0620..4d0dddd3d5 100644
--- a/wp-includes/class-wp-xmlrpc-server.php
+++ b/wp-includes/class-wp-xmlrpc-server.php
@@ -5691,7 +5691,7 @@ class wp_xmlrpc_server extends IXR_Server {
 		$attachments = $wpdb->get_results( "SELECT ID, guid FROM {$wpdb->posts} WHERE post_parent = '0' AND post_type = 'attachment'" );
 		if ( is_array( $attachments ) ) {
 			foreach ( $attachments as $file ) {
-				if ( ! empty( $file->guid ) && strpos( $post_content, $file->guid ) !== false ) {
+				if ( ! empty( $file->guid ) && str_contains( $post_content, $file->guid ) ) {
 					$wpdb->update( $wpdb->posts, array( 'post_parent' => $post_id ), array( 'ID' => $file->ID ) );
 				}
 			}
diff --git a/wp-includes/class-wp.php b/wp-includes/class-wp.php
index f669b670ff..0660c50553 100644
--- a/wp-includes/class-wp.php
+++ b/wp-includes/class-wp.php
@@ -274,10 +274,10 @@ class WP {
 			}
 
 			// If req_uri is empty or if it is a request for ourself, unset error.
-			if ( empty( $requested_path ) || $requested_file == $self || strpos( $_SERVER['PHP_SELF'], 'wp-admin/' ) !== false ) {
+			if ( empty( $requested_path ) || $requested_file == $self || str_contains( $_SERVER['PHP_SELF'], 'wp-admin/' ) ) {
 				unset( $error, $_GET['error'] );
 
-				if ( isset( $perma_query_vars ) && strpos( $_SERVER['PHP_SELF'], 'wp-admin/' ) !== false ) {
+				if ( isset( $perma_query_vars ) && str_contains( $_SERVER['PHP_SELF'], 'wp-admin/' ) ) {
 					unset( $perma_query_vars );
 				}
 
@@ -455,7 +455,7 @@ class WP {
 
 			// We're showing a feed, so WP is indeed the only thing that last changed.
 			if ( ! empty( $this->query_vars['withcomments'] )
-				|| false !== strpos( $this->query_vars['feed'], 'comments-' )
+				|| str_contains( $this->query_vars['feed'], 'comments-' )
 				|| ( empty( $this->query_vars['withoutcomments'] )
 					&& ( ! empty( $this->query_vars['p'] )
 						|| ! empty( $this->query_vars['name'] )
@@ -720,7 +720,7 @@ class WP {
 				// Check for paged content that exceeds the max number of pages.
 				if ( $post && ! empty( $this->query_vars['page'] ) ) {
 					// Check if content is actually intended to be paged.
-					if ( false !== strpos( $post->post_content, $next ) ) {
+					if ( str_contains( $post->post_content, $next ) ) {
 						$page          = trim( $this->query_vars['page'], '/' );
 						$content_found = (int) $page <= ( substr_count( $post->post_content, $next ) + 1 );
 					} else {
diff --git a/wp-includes/class-wpdb.php b/wp-includes/class-wpdb.php
index d5ed464e0b..6ea7403bf1 100644
--- a/wp-includes/class-wpdb.php
+++ b/wp-includes/class-wpdb.php
@@ -1497,7 +1497,7 @@ class wpdb {
 		}
 
 		// This is not meant to be foolproof -- but it will catch obviously incorrect usage.
-		if ( strpos( $query, '%' ) === false ) {
+		if ( ! str_contains( $query, '%' ) ) {
 			wp_load_translations_early();
 			_doing_it_wrong(
 				'wpdb::prepare',
@@ -4068,7 +4068,7 @@ class wpdb {
 				 * libmysql has supported utf8mb4 since 5.5.3, same as the MySQL server.
 				 * mysqlnd has supported utf8mb4 since 5.0.9.
 				 */
-				if ( false !== strpos( $client_version, 'mysqlnd' ) ) {
+				if ( str_contains( $client_version, 'mysqlnd' ) ) {
 					$client_version = preg_replace( '/^\D+([\d.]+).*/', '$1', $client_version );
 					return version_compare( $client_version, '5.0.9', '>=' );
 				} else {
diff --git a/wp-includes/comment-template.php b/wp-includes/comment-template.php
index 514f65acbf..3027cc606b 100644
--- a/wp-includes/comment-template.php
+++ b/wp-includes/comment-template.php
@@ -970,13 +970,13 @@ function get_comments_number_text( $zero = false, $one = false, $more = false, $
 				$text = trim( strip_tags( $text ), '% ' );
 
 				// Replace '% Comments' with a proper plural form.
-				if ( $text && ! preg_match( '/[0-9]+/', $text ) && false !== strpos( $more, '%' ) ) {
+				if ( $text && ! preg_match( '/[0-9]+/', $text ) && str_contains( $more, '%' ) ) {
 					/* translators: %s: Number of comments. */
 					$new_text = _n( '%s Comment', '%s Comments', $comments_number );
 					$new_text = trim( sprintf( $new_text, '' ) );
 
 					$more = str_replace( $text, $new_text, $more );
-					if ( false === strpos( $more, '%' ) ) {
+					if ( ! str_contains( $more, '%' ) ) {
 						$more = '% ' . $more;
 					}
 				}
@@ -2651,7 +2651,7 @@ function comment_form( $args = array(), $post = null ) {
 	$args = array_merge( $defaults, $args );
 
 	// Remove `aria-describedby` from the email field if there's no associated description.
-	if ( isset( $args['fields']['email'] ) && false === strpos( $args['comment_notes_before'], 'id="email-notes"' ) ) {
+	if ( isset( $args['fields']['email'] ) && ! str_contains( $args['comment_notes_before'], 'id="email-notes"' ) ) {
 		$args['fields']['email'] = str_replace(
 			' aria-describedby="email-notes"',
 			'',
diff --git a/wp-includes/comment.php b/wp-includes/comment.php
index 5d87da2890..b732f83ad4 100644
--- a/wp-includes/comment.php
+++ b/wp-includes/comment.php
@@ -136,7 +136,7 @@ function check_comment( $author, $email, $url, $comment, $user_ip, $user_agent,
 				$ok_to_comment = $wpdb->get_var( $wpdb->prepare( "SELECT comment_approved FROM $wpdb->comments WHERE comment_author = %s AND comment_author_email = %s and comment_approved = '1' LIMIT 1", $author, $email ) );
 			}
 			if ( ( 1 == $ok_to_comment ) &&
-				( empty( $mod_keys ) || false === strpos( $email, $mod_keys ) ) ) {
+				( empty( $mod_keys ) || ! str_contains( $email, $mod_keys ) ) ) {
 					return true;
 			} else {
 				return false;
diff --git a/wp-includes/cron.php b/wp-includes/cron.php
index 663f819ab0..b5db6a4c69 100644
--- a/wp-includes/cron.php
+++ b/wp-includes/cron.php
@@ -974,7 +974,7 @@ function wp_cron() {
  */
 function _wp_cron() {
 	// Prevent infinite loops caused by lack of wp-cron.php.
-	if ( strpos( $_SERVER['REQUEST_URI'], '/wp-cron.php' ) !== false || ( defined( 'DISABLE_WP_CRON' ) && DISABLE_WP_CRON ) ) {
+	if ( str_contains( $_SERVER['REQUEST_URI'], '/wp-cron.php' ) || ( defined( 'DISABLE_WP_CRON' ) && DISABLE_WP_CRON ) ) {
 		return 0;
 	}
 
diff --git a/wp-includes/deprecated.php b/wp-includes/deprecated.php
index ca760ff786..35c0d3094f 100644
--- a/wp-includes/deprecated.php
+++ b/wp-includes/deprecated.php
@@ -889,7 +889,7 @@ function permalink_single_rss($deprecated = '') {
 function wp_get_links($args = '') {
 	_deprecated_function( __FUNCTION__, '2.1.0', 'wp_list_bookmarks()' );
 
-	if ( strpos( $args, '=' ) === false ) {
+	if ( ! str_contains( $args, '=' ) ) {
 		$cat_id = $args;
 		$args = add_query_arg( 'category', $cat_id, $args );
 	}
@@ -995,7 +995,7 @@ function get_links($category = -1, $before = '', $after = '<br />', $between = '
 		$output .= '<a href="' . $the_link . '"' . $rel . $title . $target. '>';
 
 		if ( $row->link_image != null && $show_images ) {
-			if ( strpos($row->link_image, 'http') !== false )
+			if ( str_contains( $row->link_image, 'http' ) )
 				$output .= "<img src=\"$row->link_image\" $alt $title />";
 			else // If it's a relative path.
 				$output .= "<img src=\"" . get_option('siteurl') . "$row->link_image\" $alt $title />";
@@ -4484,7 +4484,7 @@ function wp_typography_get_css_variable_inline_style( $attributes, $feature, $cs
 	}
 
 	// If we don't have a preset CSS variable, we'll assume it's a regular CSS value.
-	if ( strpos( $style_value, "var:preset|{$css_property}|" ) === false ) {
+	if ( ! str_contains( $style_value, "var:preset|{$css_property}|" ) ) {
 		return sprintf( '%s:%s;', $css_property, $style_value );
 	}
 
diff --git a/wp-includes/feed.php b/wp-includes/feed.php
index 7b91cbb70b..e737b34d0e 100644
--- a/wp-includes/feed.php
+++ b/wp-includes/feed.php
@@ -448,7 +448,7 @@ function the_category_rss( $type = null ) {
  */
 function html_type_rss() {
 	$type = get_bloginfo( 'html_type' );
-	if ( strpos( $type, 'xhtml' ) !== false ) {
+	if ( str_contains( $type, 'xhtml' ) ) {
 		$type = 'xhtml';
 	} else {
 		$type = 'html';
@@ -580,7 +580,7 @@ function atom_enclosure() {
  * @return array array(type, value)
  */
 function prep_atom_text_construct( $data ) {
-	if ( strpos( $data, '<' ) === false && strpos( $data, '&' ) === false ) {
+	if ( ! str_contains( $data, '<' ) && ! str_contains( $data, '&' ) ) {
 		return array( 'text', $data );
 	}
 
@@ -597,7 +597,7 @@ function prep_atom_text_construct( $data ) {
 	unset( $parser );
 
 	if ( ! $code ) {
-		if ( strpos( $data, '<' ) === false ) {
+		if ( ! str_contains( $data, '<' ) ) {
 			return array( 'text', $data );
 		} else {
 			$data = "<div xmlns='http://www.w3.org/1999/xhtml'>$data</div>";
@@ -605,7 +605,7 @@ function prep_atom_text_construct( $data ) {
 		}
 	}
 
-	if ( strpos( $data, ']]>' ) === false ) {
+	if ( ! str_contains( $data, ']]>' ) ) {
 		return array( 'html', "<![CDATA[$data]]>" );
 	} else {
 		return array( 'html', htmlspecialchars( $data ) );
diff --git a/wp-includes/formatting.php b/wp-includes/formatting.php
index 9ea2b9f8fa..0782af0d2a 100644
--- a/wp-includes/formatting.php
+++ b/wp-includes/formatting.php
@@ -272,18 +272,18 @@ function wptexturize( $text, $reset = false ) {
 
 			$curl = str_replace( $static_characters, $static_replacements, $curl );
 
-			if ( false !== strpos( $curl, "'" ) ) {
+			if ( str_contains( $curl, "'" ) ) {
 				$curl = preg_replace( $dynamic_characters['apos'], $dynamic_replacements['apos'], $curl );
 				$curl = wptexturize_primes( $curl, "'", $prime, $open_sq_flag, $closing_single_quote );
 				$curl = str_replace( $apos_flag, $apos, $curl );
 				$curl = str_replace( $open_sq_flag, $opening_single_quote, $curl );
 			}
-			if ( false !== strpos( $curl, '"' ) ) {
+			if ( str_contains( $curl, '"' ) ) {
 				$curl = preg_replace( $dynamic_characters['quote'], $dynamic_replacements['quote'], $curl );
 				$curl = wptexturize_primes( $curl, '"', $double_prime, $open_q_flag, $closing_quote );
 				$curl = str_replace( $open_q_flag, $opening_quote, $curl );
 			}
-			if ( false !== strpos( $curl, '-' ) ) {
+			if ( str_contains( $curl, '-' ) ) {
 				$curl = preg_replace( $dynamic_characters['dash'], $dynamic_replacements['dash'], $curl );
 			}
 
@@ -326,7 +326,7 @@ function wptexturize_primes( $haystack, $needle, $prime, $open_quote, $close_quo
 	$sentences = explode( $open_quote, $haystack );
 
 	foreach ( $sentences as $key => &$sentence ) {
-		if ( false === strpos( $sentence, $needle ) ) {
+		if ( ! str_contains( $sentence, $needle ) ) {
 			continue;
 		} elseif ( 0 !== $key && 0 === substr_count( $sentence, $close_quote ) ) {
 			$sentence = preg_replace( $quote_pattern, $flag, $sentence, -1, $count );
@@ -362,7 +362,7 @@ function wptexturize_primes( $haystack, $needle, $prime, $open_quote, $close_quo
 			$sentence = preg_replace( $prime_pattern, $prime, $sentence );
 			$sentence = preg_replace( $quote_pattern, $close_quote, $sentence );
 		}
-		if ( '"' === $needle && false !== strpos( $sentence, '"' ) ) {
+		if ( '"' === $needle && str_contains( $sentence, '"' ) ) {
 			$sentence = str_replace( '"', $close_quote, $sentence );
 		}
 	}
@@ -453,7 +453,7 @@ function wpautop( $text, $br = true ) {
 	 * Pre tags shouldn't be touched by autop.
 	 * Replace pre tags with placeholders and bring them back after autop.
 	 */
-	if ( strpos( $text, '<pre' ) !== false ) {
+	if ( str_contains( $text, '<pre' ) ) {
 		$text_parts = explode( '</pre>', $text );
 		$last_part  = array_pop( $text_parts );
 		$text       = '';
@@ -498,7 +498,7 @@ function wpautop( $text, $br = true ) {
 	$text = wp_replace_in_html_tags( $text, array( "\n" => ' <!-- wpnl --> ' ) );
 
 	// Collapse line breaks before and after <option> elements so they don't get autop'd.
-	if ( strpos( $text, '<option' ) !== false ) {
+	if ( str_contains( $text, '<option' ) ) {
 		$text = preg_replace( '|\s*<option|', '<option', $text );
 		$text = preg_replace( '|</option>\s*|', '</option>', $text );
 	}
@@ -507,7 +507,7 @@ function wpautop( $text, $br = true ) {
 	 * Collapse line breaks inside <object> elements, before <param> and <embed> elements
 	 * so they don't get autop'd.
 	 */
-	if ( strpos( $text, '</object>' ) !== false ) {
+	if ( str_contains( $text, '</object>' ) ) {
 		$text = preg_replace( '|(<object[^>]*>)\s*|', '$1', $text );
 		$text = preg_replace( '|\s*</object>|', '</object>', $text );
 		$text = preg_replace( '%\s*(</?(?:param|embed)[^>]*>)\s*%', '$1', $text );
@@ -517,14 +517,14 @@ function wpautop( $text, $br = true ) {
 	 * Collapse line breaks inside <audio> and <video> elements,
 	 * before and after <source> and <track> elements.
 	 */
-	if ( strpos( $text, '<source' ) !== false || strpos( $text, '<track' ) !== false ) {
+	if ( str_contains( $text, '<source' ) || str_contains( $text, '<track' ) ) {
 		$text = preg_replace( '%([<\[](?:audio|video)[^>\]]*[>\]])\s*%', '$1', $text );
 		$text = preg_replace( '%\s*([<\[]/(?:audio|video)[>\]])%', '$1', $text );
 		$text = preg_replace( '%\s*(<(?:source|track)[^>]*>)\s*%', '$1', $text );
 	}
 
 	// Collapse line breaks before and after <figcaption> elements.
-	if ( strpos( $text, '<figcaption' ) !== false ) {
+	if ( str_contains( $text, '<figcaption' ) ) {
 		$text = preg_replace( '|\s*(<figcaption[^>]*>)|', '$1', $text );
 		$text = preg_replace( '|</figcaption>\s*|', '</figcaption>', $text );
 	}
@@ -593,7 +593,7 @@ function wpautop( $text, $br = true ) {
 	}
 
 	// Restore newlines in all elements.
-	if ( false !== strpos( $text, '<!-- wpnl -->' ) ) {
+	if ( str_contains( $text, '<!-- wpnl -->' ) ) {
 		$text = str_replace( array( ' <!-- wpnl --> ', '<!-- wpnl -->' ), "\n", $text );
 	}
 
@@ -763,7 +763,7 @@ function wp_replace_in_html_tags( $haystack, $replace_pairs ) {
 
 		// Loop through delimiters (elements) only.
 		for ( $i = 1, $c = count( $textarr ); $i < $c; $i += 2 ) {
-			if ( false !== strpos( $textarr[ $i ], $needle ) ) {
+			if ( str_contains( $textarr[ $i ], $needle ) ) {
 				$textarr[ $i ] = str_replace( $needle, $replace, $textarr[ $i ] );
 				$changed       = true;
 			}
@@ -775,7 +775,7 @@ function wp_replace_in_html_tags( $haystack, $replace_pairs ) {
 		// Loop through delimiters (elements) only.
 		for ( $i = 1, $c = count( $textarr ); $i < $c; $i += 2 ) {
 			foreach ( $needles as $needle ) {
-				if ( false !== strpos( $textarr[ $i ], $needle ) ) {
+				if ( str_contains( $textarr[ $i ], $needle ) ) {
 					$textarr[ $i ] = strtr( $textarr[ $i ], $replace_pairs );
 					$changed       = true;
 					// After one strtr() break out of the foreach loop and look at next element.
@@ -2055,7 +2055,7 @@ function sanitize_file_name( $filename ) {
 	$filename = preg_replace( '/[\r\n\t -]+/', '-', $filename );
 	$filename = trim( $filename, '.-_' );
 
-	if ( false === strpos( $filename, '.' ) ) {
+	if ( ! str_contains( $filename, '.' ) ) {
 		$mime_types = wp_get_mime_types();
 		$filetype   = wp_check_filetype( 'test.' . $filename, $mime_types );
 		if ( $filetype['ext'] === $filename ) {
@@ -4475,7 +4475,7 @@ function esc_url( $url, $protocols = null, $_context = 'display' ) {
 		$url = str_replace( "'", '&#039;', $url );
 	}
 
-	if ( ( false !== strpos( $url, '[' ) ) || ( false !== strpos( $url, ']' ) ) ) {
+	if ( ( str_contains( $url, '[' ) ) || ( str_contains( $url, ']' ) ) ) {
 
 		$parsed = wp_parse_url( $url );
 		$front  = '';
@@ -5143,7 +5143,7 @@ function wp_pre_kses_less_than( $content ) {
  * @return string The text returned after esc_html if needed.
  */
 function wp_pre_kses_less_than_callback( $matches ) {
-	if ( false === strpos( $matches[0], '>' ) ) {
+	if ( ! str_contains( $matches[0], '>' ) ) {
 		return esc_html( $matches[0] );
 	}
 	return $matches[0];
@@ -5932,7 +5932,7 @@ function wp_encode_emoji( $content ) {
 
 	foreach ( $emoji as $emojum ) {
 		$emoji_char = html_entity_decode( $emojum );
-		if ( false !== strpos( $content, $emoji_char ) ) {
+		if ( str_contains( $content, $emoji_char ) ) {
 			$content = preg_replace( "/$emoji_char/", $emojum, $content );
 		}
 	}
@@ -5949,7 +5949,7 @@ function wp_encode_emoji( $content ) {
  * @return string The encoded content.
  */
 function wp_staticize_emoji( $text ) {
-	if ( false === strpos( $text, '&#x' ) ) {
+	if ( ! str_contains( $text, '&#x' ) ) {
 		if ( ( function_exists( 'mb_check_encoding' ) && mb_check_encoding( $text, 'ASCII' ) ) || ! preg_match( '/[^\x00-\x7F]/', $text ) ) {
 			// The text doesn't contain anything that might be emoji, so we can return early.
 			return $text;
@@ -5968,7 +5968,7 @@ function wp_staticize_emoji( $text ) {
 	// Quickly narrow down the list of emoji that might be in the text and need replacing.
 	$possible_emoji = array();
 	foreach ( $emoji as $emojum ) {
-		if ( false !== strpos( $text, $emojum ) ) {
+		if ( str_contains( $text, $emojum ) ) {
 			$possible_emoji[ $emojum ] = html_entity_decode( $emojum );
 		}
 	}
@@ -6006,9 +6006,9 @@ function wp_staticize_emoji( $text ) {
 		}
 
 		// If it's not a tag and not in ignore block.
-		if ( '' === $ignore_block_element && strlen( $content ) > 0 && '<' !== $content[0] && false !== strpos( $content, '&#x' ) ) {
+		if ( '' === $ignore_block_element && strlen( $content ) > 0 && '<' !== $content[0] && str_contains( $content, '&#x' ) ) {
 			foreach ( $possible_emoji as $emojum => $emoji_char ) {
-				if ( false === strpos( $content, $emojum ) ) {
+				if ( ! str_contains( $content, $emojum ) ) {
 					continue;
 				}
 
diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index 11e36bfd03..3e63d18d24 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -708,7 +708,7 @@ function is_serialized( $data, $strict = true ) {
 				if ( '"' !== substr( $data, -2, 1 ) ) {
 					return false;
 				}
-			} elseif ( false === strpos( $data, '"' ) ) {
+			} elseif ( ! str_contains( $data, '"' ) ) {
 				return false;
 			}
 			// Or else fall through.
@@ -1158,10 +1158,10 @@ function add_query_arg( ...$args ) {
 		$protocol = '';
 	}
 
-	if ( strpos( $uri, '?' ) !== false ) {
+	if ( str_contains( $uri, '?' ) ) {
 		list( $base, $query ) = explode( '?', $uri, 2 );
 		$base                .= '?';
-	} elseif ( $protocol || strpos( $uri, '=' ) === false ) {
+	} elseif ( $protocol || ! str_contains( $uri, '=' ) ) {
 		$base  = $uri . '?';
 		$query = '';
 	} else {
@@ -2054,7 +2054,7 @@ function wp_mkdir_p( $target ) {
 	}
 
 	// Do not allow path traversals.
-	if ( false !== strpos( $target, '../' ) || false !== strpos( $target, '..' . DIRECTORY_SEPARATOR ) ) {
+	if ( str_contains( $target, '../' ) || str_contains( $target, '..' . DIRECTORY_SEPARATOR ) ) {
 		return false;
 	}
 
@@ -2641,7 +2641,7 @@ function wp_unique_filename( $dir, $filename, $unique_filename_callback = null )
 		$count = 10000;
 
 		// The (resized) image files would have name and extension, and will be in the uploads dir.
-		if ( $name && $ext && @is_dir( $dir ) && false !== strpos( $dir, $upload_dir['basedir'] ) ) {
+		if ( $name && $ext && @is_dir( $dir ) && str_contains( $dir, $upload_dir['basedir'] ) ) {
 			/**
 			 * Filters the file list used for calculating a unique filename for a newly added file.
 			 *
@@ -4656,7 +4656,7 @@ function _mce_set_direction( $mce_init ) {
 		$mce_init['directionality'] = 'rtl';
 		$mce_init['rtl_ui']         = true;
 
-		if ( ! empty( $mce_init['plugins'] ) && strpos( $mce_init['plugins'], 'directionality' ) === false ) {
+		if ( ! empty( $mce_init['plugins'] ) && ! str_contains( $mce_init['plugins'], 'directionality' ) ) {
 			$mce_init['plugins'] .= ',directionality';
 		}
 
@@ -5968,13 +5968,13 @@ function apache_mod_loaded( $mod, $default_value = false ) {
 
 	if ( empty( $loaded_mods )
 		&& function_exists( 'phpinfo' )
-		&& false === strpos( ini_get( 'disable_functions' ), 'phpinfo' )
+		&& ! str_contains( ini_get( 'disable_functions' ), 'phpinfo' )
 	) {
 		ob_start();
 		phpinfo( INFO_MODULES );
 		$phpinfo = ob_get_clean();
 
-		if ( false !== strpos( $phpinfo, $mod ) ) {
+		if ( str_contains( $phpinfo, $mod ) ) {
 			return true;
 		}
 	}
@@ -6049,7 +6049,7 @@ function validate_file( $file, $allowed_files = array() ) {
 	}
 
 	// `../` which does not occur at the end of the path is not allowed:
-	if ( false !== strpos( $file, '../' ) && '../' !== mb_substr( $file, -3, 3 ) ) {
+	if ( str_contains( $file, '../' ) && '../' !== mb_substr( $file, -3, 3 ) ) {
 		return 1;
 	}
 
@@ -6104,7 +6104,7 @@ function wp_guess_url() {
 		$script_filename_dir = dirname( $_SERVER['SCRIPT_FILENAME'] );
 
 		// The request is for the admin.
-		if ( strpos( $_SERVER['REQUEST_URI'], 'wp-admin' ) !== false || strpos( $_SERVER['REQUEST_URI'], 'wp-login.php' ) !== false ) {
+		if ( strpos( $_SERVER['REQUEST_URI'], 'wp-admin' ) !== false || str_contains( $_SERVER['REQUEST_URI'], 'wp-login.php' ) ) {
 			$path = preg_replace( '#/(wp-admin/?.*|wp-login\.php.*)#i', '', $_SERVER['REQUEST_URI'] );
 
 			// The request is for a file in ABSPATH.
@@ -6113,12 +6113,12 @@ function wp_guess_url() {
 			$path = preg_replace( '#/[^/]*$#i', '', $_SERVER['PHP_SELF'] );
 
 		} else {
-			if ( false !== strpos( $_SERVER['SCRIPT_FILENAME'], $abspath_fix ) ) {
+			if ( str_contains( $_SERVER['SCRIPT_FILENAME'], $abspath_fix ) ) {
 				// Request is hitting a file inside ABSPATH.
 				$directory = str_replace( ABSPATH, '', $script_filename_dir );
 				// Strip off the subdirectory, and any file/query params.
 				$path = preg_replace( '#/' . preg_quote( $directory, '#' ) . '/[^/]*$#i', '', $_SERVER['REQUEST_URI'] );
-			} elseif ( false !== strpos( $abspath_fix, $script_filename_dir ) ) {
+			} elseif ( str_contains( $abspath_fix, $script_filename_dir ) ) {
 				// Request is hitting a file above ABSPATH.
 				$subdirectory = substr( $abspath_fix, strpos( $abspath_fix, $script_filename_dir ) + strlen( $script_filename_dir ) );
 				// Strip off any file/query params from the path, appending the subdirectory to the installation.
@@ -7104,9 +7104,9 @@ function _device_can_upload() {
 
 	$ua = $_SERVER['HTTP_USER_AGENT'];
 
-	if ( strpos( $ua, 'iPhone' ) !== false
-		|| strpos( $ua, 'iPad' ) !== false
-		|| strpos( $ua, 'iPod' ) !== false ) {
+	if ( str_contains( $ua, 'iPhone' )
+		|| str_contains( $ua, 'iPad' )
+		|| str_contains( $ua, 'iPod' ) ) {
 			return preg_match( '#OS ([\d_]+) like Mac OS X#', $ua, $version ) && version_compare( $version[1], '6', '>=' );
 	}
 
@@ -8510,8 +8510,8 @@ function clean_dirsize_cache( $path ) {
 	}
 
 	if (
-		strpos( $path, '/' ) === false &&
-		strpos( $path, '\\' ) === false
+		! str_contains( $path, '/' ) &&
+		! str_contains( $path, '\\' )
 	) {
 		unset( $directory_cache[ $path ] );
 		set_transient( 'dirsize_cache', $directory_cache );
diff --git a/wp-includes/general-template.php b/wp-includes/general-template.php
index 698c5fcace..24ea995c7b 100644
--- a/wp-includes/general-template.php
+++ b/wp-includes/general-template.php
@@ -4021,7 +4021,7 @@ function wp_get_code_editor_settings( $args ) {
 		if ( 'application/x-patch' === $type || 'text/x-patch' === $type ) {
 			$type = 'text/x-diff';
 		}
-	} elseif ( isset( $args['file'] ) && false !== strpos( basename( $args['file'] ), '.' ) ) {
+	} elseif ( isset( $args['file'] ) && str_contains( basename( $args['file'] ), '.' ) ) {
 		$extension = strtolower( pathinfo( $args['file'], PATHINFO_EXTENSION ) );
 		foreach ( wp_get_mime_types() as $exts => $mime ) {
 			if ( preg_match( '!^(' . $exts . ')$!i', $extension ) ) {
@@ -4157,7 +4157,7 @@ function wp_get_code_editor_settings( $args ) {
 				'matchBrackets'     => true,
 			)
 		);
-	} elseif ( false !== strpos( $type, 'json' ) ) {
+	} elseif ( str_contains( $type, 'json' ) ) {
 		$settings['codemirror'] = array_merge(
 			$settings['codemirror'],
 			array(
@@ -4174,7 +4174,7 @@ function wp_get_code_editor_settings( $args ) {
 		} else {
 			$settings['codemirror']['mode']['json'] = true;
 		}
-	} elseif ( false !== strpos( $type, 'jsx' ) ) {
+	} elseif ( str_contains( $type, 'jsx' ) ) {
 		$settings['codemirror'] = array_merge(
 			$settings['codemirror'],
 			array(
@@ -4220,7 +4220,7 @@ function wp_get_code_editor_settings( $args ) {
 				'matchBrackets'     => true,
 			)
 		);
-	} elseif ( false !== strpos( $type, 'xml' ) ) {
+	} elseif ( str_contains( $type, 'xml' ) ) {
 		$settings['codemirror'] = array_merge(
 			$settings['codemirror'],
 			array(
diff --git a/wp-includes/global-styles-and-settings.php b/wp-includes/global-styles-and-settings.php
index 4895b6daa9..15f24c1cb4 100644
--- a/wp-includes/global-styles-and-settings.php
+++ b/wp-includes/global-styles-and-settings.php
@@ -371,7 +371,7 @@ function wp_add_global_styles_for_blocks() {
 				array_filter(
 					$metadata['path'],
 					function ( $item ) {
-						if ( strpos( $item, 'core/' ) !== false ) {
+						if ( str_contains( $item, 'core/' ) ) {
 							return true;
 						}
 						return false;
diff --git a/wp-includes/https-detection.php b/wp-includes/https-detection.php
index 1ef3fb8c59..955e4b7dde 100644
--- a/wp-includes/https-detection.php
+++ b/wp-includes/https-detection.php
@@ -205,14 +205,14 @@ function wp_is_local_html_output( $html ) {
 	// 1. Check if HTML includes the site's Really Simple Discovery link.
 	if ( has_action( 'wp_head', 'rsd_link' ) ) {
 		$pattern = preg_replace( '#^https?:(?=//)#', '', esc_url( site_url( 'xmlrpc.php?rsd', 'rpc' ) ) ); // See rsd_link().
-		return false !== strpos( $html, $pattern );
+		return str_contains( $html, $pattern );
 	}
 
 	// 2. Check if HTML includes the site's REST API link.
 	if ( has_action( 'wp_head', 'rest_output_link_wp_head' ) ) {
 		// Try both HTTPS and HTTP since the URL depends on context.
 		$pattern = preg_replace( '#^https?:(?=//)#', '', esc_url( get_rest_url() ) ); // See rest_output_link_wp_head().
-		return false !== strpos( $html, $pattern );
+		return str_contains( $html, $pattern );
 	}
 
 	// Otherwise the result cannot be determined.
diff --git a/wp-includes/kses.php b/wp-includes/kses.php
index cafc64b1d1..380b2d589d 100644
--- a/wp-includes/kses.php
+++ b/wp-includes/kses.php
@@ -2499,7 +2499,7 @@ function safecss_filter_attr( $css, $deprecated = '' ) {
 		$gradient_attr   = false;
 		$is_custom_var   = false;
 
-		if ( strpos( $css_item, ':' ) === false ) {
+		if ( ! str_contains( $css_item, ':' ) ) {
 			$found = true;
 		} else {
 			$parts        = explode( ':', $css_item, 2 );
diff --git a/wp-includes/link-template.php b/wp-includes/link-template.php
index 28c65c8d0a..16c9da2d3b 100644
--- a/wp-includes/link-template.php
+++ b/wp-includes/link-template.php
@@ -496,7 +496,7 @@ function get_attachment_link( $post = null, $leavename = false ) {
 			$parentlink = get_permalink( $post->post_parent );
 		}
 
-		if ( is_numeric( $post->post_name ) || false !== strpos( get_option( 'permalink_structure' ), '%category%' ) ) {
+		if ( is_numeric( $post->post_name ) || str_contains( get_option( 'permalink_structure' ), '%category%' ) ) {
 			$name = 'attachment/' . $post->post_name; // <permalink>/<int>/ is paged so we use the explicit attachment marker.
 		} else {
 			$name = $post->post_name;
@@ -692,7 +692,7 @@ function get_feed_link( $feed = '' ) {
 	$permalink = $wp_rewrite->get_feed_permastruct();
 
 	if ( $permalink ) {
-		if ( false !== strpos( $feed, 'comments_' ) ) {
+		if ( str_contains( $feed, 'comments_' ) ) {
 			$feed      = str_replace( 'comments_', '', $feed );
 			$permalink = $wp_rewrite->get_comment_feed_permastruct();
 		}
@@ -709,7 +709,7 @@ function get_feed_link( $feed = '' ) {
 			$feed = get_default_feed();
 		}
 
-		if ( false !== strpos( $feed, 'comments_' ) ) {
+		if ( str_contains( $feed, 'comments_' ) ) {
 			$feed = str_replace( 'comments_', 'comments-', $feed );
 		}
 
@@ -1820,7 +1820,7 @@ function get_adjacent_post( $in_same_term = false, $excluded_terms = '', $previo
 
 	if ( ! empty( $excluded_terms ) && ! is_array( $excluded_terms ) ) {
 		// Back-compat, $excluded_terms used to be $excluded_categories with IDs separated by " and ".
-		if ( false !== strpos( $excluded_terms, ' and ' ) ) {
+		if ( str_contains( $excluded_terms, ' and ' ) ) {
 			_deprecated_argument(
 				__FUNCTION__,
 				'3.3.0',
diff --git a/wp-includes/media.php b/wp-includes/media.php
index b74933881f..bf803f5773 100644
--- a/wp-includes/media.php
+++ b/wp-includes/media.php
@@ -1168,7 +1168,7 @@ function _wp_get_attachment_relative_path( $file ) {
 		return '';
 	}
 
-	if ( false !== strpos( $dirname, 'wp-content/uploads' ) ) {
+	if ( str_contains( $dirname, 'wp-content/uploads' ) ) {
 		// Get the directory name relative to the upload directory (back compat for pre-2.7 uploads).
 		$dirname = substr( $dirname, strpos( $dirname, 'wp-content/uploads' ) + 18 );
 		$dirname = ltrim( $dirname, '/' );
@@ -1373,7 +1373,7 @@ function wp_calculate_image_srcset( $size_array, $image_src, $image_meta, $attac
 		}
 
 		// If the file name is part of the `src`, we've confirmed a match.
-		if ( ! $src_matched && false !== strpos( $image_src, $dirname . $image['file'] ) ) {
+		if ( ! $src_matched && str_contains( $image_src, $dirname . $image['file'] ) ) {
 			$src_matched = true;
 			$is_src      = true;
 		}
@@ -1625,7 +1625,7 @@ function wp_image_src_get_dimensions( $image_src, $image_meta, $attachment_id =
 	// Is it a full size image?
 	if (
 		isset( $image_meta['file'] ) &&
-		strpos( $image_src, wp_basename( $image_meta['file'] ) ) !== false
+		str_contains( $image_src, wp_basename( $image_meta['file'] ) )
 	) {
 		$dimensions = array(
 			(int) $image_meta['width'],
@@ -1693,7 +1693,7 @@ function wp_image_add_srcset_and_sizes( $image, $image_meta, $attachment_id ) {
 
 	// Bail early if an image has been inserted and later edited.
 	if ( preg_match( '/-e[0-9]{13}/', $image_meta['file'], $img_edit_hash ) &&
-		strpos( wp_basename( $image_src ), $img_edit_hash[0] ) === false ) {
+		 ! str_contains( wp_basename( $image_src ), $img_edit_hash[0] ) ) {
 
 		return $image;
 	}
@@ -1848,17 +1848,17 @@ function wp_filter_content_tags( $content, $context = null ) {
 			$attachment_id  = $images[ $match[0] ];
 
 			// Add 'width' and 'height' attributes if applicable.
-			if ( $attachment_id > 0 && false === strpos( $filtered_image, ' width=' ) && false === strpos( $filtered_image, ' height=' ) ) {
+			if ( $attachment_id > 0 && ! str_contains( $filtered_image, ' width=' ) && ! str_contains( $filtered_image, ' height=' ) ) {
 				$filtered_image = wp_img_tag_add_width_and_height_attr( $filtered_image, $context, $attachment_id );
 			}
 
 			// Add 'srcset' and 'sizes' attributes if applicable.
-			if ( $attachment_id > 0 && false === strpos( $filtered_image, ' srcset=' ) ) {
+			if ( $attachment_id > 0 && ! str_contains( $filtered_image, ' srcset=' ) ) {
 				$filtered_image = wp_img_tag_add_srcset_and_sizes_attr( $filtered_image, $context, $attachment_id );
 			}
 
 			// Add 'loading' attribute if applicable.
-			if ( $add_img_loading_attr && false === strpos( $filtered_image, ' loading=' ) ) {
+			if ( $add_img_loading_attr && ! str_contains( $filtered_image, ' loading=' ) ) {
 				$filtered_image = wp_img_tag_add_loading_attr( $filtered_image, $context );
 			}
 
@@ -1894,7 +1894,7 @@ function wp_filter_content_tags( $content, $context = null ) {
 			$filtered_iframe = $match[0];
 
 			// Add 'loading' attribute if applicable.
-			if ( $add_iframe_loading_attr && false === strpos( $filtered_iframe, ' loading=' ) ) {
+			if ( $add_iframe_loading_attr && ! str_contains( $filtered_iframe, ' loading=' ) ) {
 				$filtered_iframe = wp_iframe_tag_add_loading_attr( $filtered_iframe, $context );
 			}
 
@@ -1928,7 +1928,7 @@ function wp_img_tag_add_loading_attr( $image, $context ) {
 	$value = wp_get_loading_attr_default( $context );
 
 	// Images should have source and dimension attributes for the `loading` attribute to be added.
-	if ( false === strpos( $image, ' src="' ) || false === strpos( $image, ' width="' ) || false === strpos( $image, ' height="' ) ) {
+	if ( ! str_contains( $image, ' src="' ) || ! str_contains( $image, ' width="' ) || ! str_contains( $image, ' height="' ) ) {
 		return $image;
 	}
 
@@ -1979,7 +1979,7 @@ function wp_img_tag_add_loading_attr( $image, $context ) {
 function wp_img_tag_add_decoding_attr( $image, $context ) {
 	// Only apply the decoding attribute to images that have a src attribute that
 	// starts with a double quote, ensuring escaped JSON is also excluded.
-	if ( false === strpos( $image, ' src="' ) ) {
+	if ( ! str_contains( $image, ' src="' ) ) {
 		return $image;
 	}
 
@@ -2097,7 +2097,7 @@ function wp_img_tag_add_srcset_and_sizes_attr( $image, $context, $attachment_id
 function wp_iframe_tag_add_loading_attr( $iframe, $context ) {
 	// Iframes with fallback content (see `wp_filter_oembed_result()`) should not be lazy-loaded because they are
 	// visually hidden initially.
-	if ( false !== strpos( $iframe, ' data-secret="' ) ) {
+	if ( str_contains( $iframe, ' data-secret="' ) ) {
 		return $iframe;
 	}
 
@@ -2106,7 +2106,7 @@ function wp_iframe_tag_add_loading_attr( $iframe, $context ) {
 	$value = wp_get_loading_attr_default( $context );
 
 	// Iframes should have source and dimension attributes for the `loading` attribute to be added.
-	if ( false === strpos( $iframe, ' src="' ) || false === strpos( $iframe, ' width="' ) || false === strpos( $iframe, ' height="' ) ) {
+	if ( ! str_contains( $iframe, ' src="' ) || ! str_contains( $iframe, ' width="' ) || ! str_contains( $iframe, ' height="' ) ) {
 		return $iframe;
 	}
 
@@ -2259,7 +2259,7 @@ function img_caption_shortcode( $attr, $content = '' ) {
 			$content         = $matches[1];
 			$attr['caption'] = trim( $matches[2] );
 		}
-	} elseif ( strpos( $attr['caption'], '<' ) !== false ) {
+	} elseif ( str_contains( $attr['caption'], '<' ) ) {
 		$attr['caption'] = wp_kses( $attr['caption'], 'post' );
 	}
 
@@ -3524,7 +3524,7 @@ function wp_video_shortcode( $attr, $content = '' ) {
 	}
 
 	if ( ! empty( $content ) ) {
-		if ( false !== strpos( $content, "\n" ) ) {
+		if ( str_contains( $content, "\n" ) ) {
 			$content = str_replace( array( "\r\n", "\n", "\t" ), '', $content );
 		}
 		$html .= trim( $content );
@@ -3729,14 +3729,14 @@ function get_attachment_taxonomies( $attachment, $output = 'names' ) {
 
 	$objects = array( 'attachment' );
 
-	if ( false !== strpos( $filename, '.' ) ) {
+	if ( str_contains( $filename, '.' ) ) {
 		$objects[] = 'attachment:' . substr( $filename, strrpos( $filename, '.' ) + 1 );
 	}
 
 	if ( ! empty( $attachment->post_mime_type ) ) {
 		$objects[] = 'attachment:' . $attachment->post_mime_type;
 
-		if ( false !== strpos( $attachment->post_mime_type, '/' ) ) {
+		if ( str_contains( $attachment->post_mime_type, '/' ) ) {
 			foreach ( explode( '/', $attachment->post_mime_type ) as $token ) {
 				if ( ! empty( $token ) ) {
 					$objects[] = "attachment:$token";
@@ -4030,7 +4030,7 @@ function wp_plupload_default_settings() {
 	$wp_scripts = wp_scripts();
 
 	$data = $wp_scripts->get_data( 'wp-plupload', 'data' );
-	if ( $data && false !== strpos( $data, '_wpPluploadSettings' ) ) {
+	if ( $data && str_contains( $data, '_wpPluploadSettings' ) ) {
 		return;
 	}
 
@@ -4175,7 +4175,7 @@ function wp_prepare_attachment_for_js( $attachment ) {
 	}
 
 	$meta = wp_get_attachment_metadata( $attachment->ID );
-	if ( false !== strpos( $attachment->post_mime_type, '/' ) ) {
+	if ( str_contains( $attachment->post_mime_type, '/' ) ) {
 		list( $type, $subtype ) = explode( '/', $attachment->post_mime_type );
 	} else {
 		list( $type, $subtype ) = array( $attachment->post_mime_type, '' );
diff --git a/wp-includes/ms-deprecated.php b/wp-includes/ms-deprecated.php
index 87ecfdf5c9..8ef357857c 100644
--- a/wp-includes/ms-deprecated.php
+++ b/wp-includes/ms-deprecated.php
@@ -317,8 +317,8 @@ function wpmu_admin_do_redirect( $url = '' ) {
 function wpmu_admin_redirect_add_updated_param( $url = '' ) {
 	_deprecated_function( __FUNCTION__, '3.3.0', 'add_query_arg()' );
 
-	if ( strpos( $url, 'updated=true' ) === false ) {
-		if ( strpos( $url, '?' ) === false )
+	if ( ! str_contains( $url, 'updated=true' ) ) {
+		if ( ! str_contains( $url, '?' ) )
 			return $url . '?updated=true';
 		else
 			return $url . '&updated=true';
diff --git a/wp-includes/ms-files.php b/wp-includes/ms-files.php
index 6fb7e4d276..6026a71db6 100644
--- a/wp-includes/ms-files.php
+++ b/wp-includes/ms-files.php
@@ -41,7 +41,7 @@ if ( $mime['type'] ) {
 }
 
 header( 'Content-Type: ' . $mimetype ); // Always send this.
-if ( false === strpos( $_SERVER['SERVER_SOFTWARE'], 'Microsoft-IIS' ) ) {
+if ( ! str_contains( $_SERVER['SERVER_SOFTWARE'], 'Microsoft-IIS' ) ) {
 	header( 'Content-Length: ' . filesize( $file ) );
 }
 
diff --git a/wp-includes/ms-functions.php b/wp-includes/ms-functions.php
index 7bd74f2e36..bf62d0c127 100644
--- a/wp-includes/ms-functions.php
+++ b/wp-includes/ms-functions.php
@@ -1992,7 +1992,7 @@ function check_upload_mimes( $mimes ) {
 	$site_mimes = array();
 	foreach ( $site_exts as $ext ) {
 		foreach ( $mimes as $ext_pattern => $mime ) {
-			if ( '' !== $ext && false !== strpos( $ext_pattern, $ext ) ) {
+			if ( '' !== $ext && str_contains( $ext_pattern, $ext ) ) {
 				$site_mimes[ $ext_pattern ] = $mime;
 			}
 		}
@@ -2165,7 +2165,7 @@ function maybe_redirect_404() {
  * @since MU (3.0.0)
  */
 function maybe_add_existing_user_to_blog() {
-	if ( false === strpos( $_SERVER['REQUEST_URI'], '/newbloguser/' ) ) {
+	if ( ! str_contains( $_SERVER['REQUEST_URI'], '/newbloguser/' ) ) {
 		return;
 	}
 
diff --git a/wp-includes/pluggable.php b/wp-includes/pluggable.php
index 9a811edc3a..d8549d0abe 100644
--- a/wp-includes/pluggable.php
+++ b/wp-includes/pluggable.php
@@ -279,7 +279,7 @@ if ( ! function_exists( 'wp_mail' ) ) :
 			if ( ! empty( $tempheaders ) ) {
 				// Iterate through the raw headers.
 				foreach ( (array) $tempheaders as $header ) {
-					if ( strpos( $header, ':' ) === false ) {
+					if ( ! str_contains( $header, ':' ) ) {
 						if ( false !== stripos( $header, 'boundary=' ) ) {
 							$parts    = preg_split( '/boundary=/i', trim( $header ) );
 							$boundary = trim( str_replace( array( "'", '"' ), '', $parts[1] ) );
@@ -315,7 +315,7 @@ if ( ! function_exists( 'wp_mail' ) ) :
 							}
 							break;
 						case 'content-type':
-							if ( strpos( $content, ';' ) !== false ) {
+							if ( str_contains( $content, ';' ) ) {
 								list( $type, $charset_content ) = explode( ';', $content );
 								$content_type                   = trim( $type );
 								if ( false !== stripos( $charset_content, 'charset=' ) ) {
@@ -1186,7 +1186,7 @@ if ( ! function_exists( 'auth_redirect' ) ) :
 		$secure = apply_filters( 'secure_auth_redirect', $secure );
 
 		// If https is required and request is http, redirect.
-		if ( $secure && ! is_ssl() && false !== strpos( $_SERVER['REQUEST_URI'], 'wp-admin' ) ) {
+		if ( $secure && ! is_ssl() && str_contains( $_SERVER['REQUEST_URI'], 'wp-admin' ) ) {
 			if ( str_starts_with( $_SERVER['REQUEST_URI'], 'http' ) ) {
 				wp_redirect( set_url_scheme( $_SERVER['REQUEST_URI'], 'https' ) );
 				exit;
@@ -1217,7 +1217,7 @@ if ( ! function_exists( 'auth_redirect' ) ) :
 			do_action( 'auth_redirect', $user_id );
 
 			// If the user wants ssl but the session is not ssl, redirect.
-			if ( ! $secure && get_user_option( 'use_ssl', $user_id ) && false !== strpos( $_SERVER['REQUEST_URI'], 'wp-admin' ) ) {
+			if ( ! $secure && get_user_option( 'use_ssl', $user_id ) && str_contains( $_SERVER['REQUEST_URI'], 'wp-admin' ) ) {
 				if ( str_starts_with( $_SERVER['REQUEST_URI'], 'http' ) ) {
 					wp_redirect( set_url_scheme( $_SERVER['REQUEST_URI'], 'https' ) );
 					exit;
diff --git a/wp-includes/pomo/po.php b/wp-includes/pomo/po.php
index 4a61aa8072..a443765707 100644
--- a/wp-includes/pomo/po.php
+++ b/wp-includes/pomo/po.php
@@ -128,7 +128,7 @@ if ( ! class_exists( 'PO', false ) ) :
 
 			$po = $quote . implode( "{$slash}n{$quote}{$newline}{$quote}", explode( $newline, $input_string ) ) . $quote;
 			// Add empty string on first line for readbility.
-			if ( false !== strpos( $input_string, $newline ) &&
+			if ( str_contains( $input_string, $newline ) &&
 				( substr_count( $input_string, $newline ) > 1 || substr( $input_string, -strlen( $newline ) ) !== $newline ) ) {
 				$po = "$quote$quote$newline$po";
 			}
diff --git a/wp-includes/post-template.php b/wp-includes/post-template.php
index 083af5ad6d..f6bca3ed8b 100644
--- a/wp-includes/post-template.php
+++ b/wp-includes/post-template.php
@@ -343,7 +343,7 @@ function get_the_content( $more_link_text = null, $strip_teaser = false, $post =
 		$content = array( $content );
 	}
 
-	if ( false !== strpos( $_post->post_content, '<!--noteaser-->' ) && ( ! $elements['multipage'] || 1 == $elements['page'] ) ) {
+	if ( str_contains( $_post->post_content, '<!--noteaser-->' ) && ( ! $elements['multipage'] || 1 == $elements['page'] ) ) {
 		$strip_teaser = true;
 	}
 
diff --git a/wp-includes/post.php b/wp-includes/post.php
index 1d543fe986..2b39d90c18 100644
--- a/wp-includes/post.php
+++ b/wp-includes/post.php
@@ -2774,7 +2774,7 @@ function sanitize_post_field( $field, $value, $post_id, $context = 'display' ) {
 	}
 
 	$prefixed = false;
-	if ( false !== strpos( $field, 'post_' ) ) {
+	if ( str_contains( $field, 'post_' ) ) {
 		$prefixed        = true;
 		$field_no_prefix = str_replace( 'post_', '', $field );
 	}
@@ -3273,7 +3273,7 @@ function wp_match_mime_types( $wildcard_mime_types, $real_mime_types ) {
 
 			$patternses[][ $type ] = "^$regex$";
 
-			if ( false === strpos( $mime, '/' ) ) {
+			if ( ! str_contains( $mime, '/' ) ) {
 				$patternses[][ $type ] = "^$regex/";
 				$patternses[][ $type ] = $regex;
 			}
@@ -3330,7 +3330,7 @@ function wp_post_mime_type_where( $post_mime_types, $table_alias = '' ) {
 			$mime_pattern = "$mime_group/$mime_subgroup";
 		} else {
 			$mime_pattern = preg_replace( '/[^-*.a-zA-Z0-9]/', '', $mime_type );
-			if ( false === strpos( $mime_pattern, '*' ) ) {
+			if ( ! str_contains( $mime_pattern, '*' ) ) {
 				$mime_pattern .= '/*';
 			}
 		}
@@ -3341,7 +3341,7 @@ function wp_post_mime_type_where( $post_mime_types, $table_alias = '' ) {
 			return '';
 		}
 
-		if ( false !== strpos( $mime_pattern, '%' ) ) {
+		if ( str_contains( $mime_pattern, '%' ) ) {
 			$wheres[] = empty( $table_alias ) ? "post_mime_type LIKE '$mime_pattern'" : "$table_alias.post_mime_type LIKE '$mime_pattern'";
 		} else {
 			$wheres[] = empty( $table_alias ) ? "post_mime_type = '$mime_pattern'" : "$table_alias.post_mime_type = '$mime_pattern'";
@@ -6124,10 +6124,10 @@ function get_pages( $args = array() ) {
  * @return bool True on success, false on failure.
  */
 function is_local_attachment( $url ) {
-	if ( strpos( $url, home_url() ) === false ) {
+	if ( ! str_contains( $url, home_url() ) ) {
 		return false;
 	}
-	if ( strpos( $url, home_url( '/?attachment_id=' ) ) !== false ) {
+	if ( str_contains( $url, home_url( '/?attachment_id=' ) ) ) {
 		return true;
 	}
 
@@ -6510,7 +6510,7 @@ function wp_get_attachment_url( $attachment_id = 0 ) {
 			if ( str_starts_with( $file, $uploads['basedir'] ) ) {
 				// Replace file location with url location.
 				$url = str_replace( $uploads['basedir'], $uploads['baseurl'], $file );
-			} elseif ( false !== strpos( $file, 'wp-content/uploads' ) ) {
+			} elseif ( str_contains( $file, 'wp-content/uploads' ) ) {
 				// Get the directory name relative to the basedir (back compat for pre-2.7 uploads).
 				$url = trailingslashit( $uploads['baseurl'] . '/' . _wp_get_attachment_relative_path( $file ) ) . wp_basename( $file );
 			} else {
diff --git a/wp-includes/rest-api/class-wp-rest-request.php b/wp-includes/rest-api/class-wp-rest-request.php
index b708df6cc7..28b1288acd 100644
--- a/wp-includes/rest-api/class-wp-rest-request.php
+++ b/wp-includes/rest-api/class-wp-rest-request.php
@@ -311,7 +311,7 @@ class WP_REST_Request implements ArrayAccess {
 		}
 
 		$value = strtolower( $value );
-		if ( false === strpos( $value, '/' ) ) {
+		if ( ! str_contains( $value, '/' ) ) {
 			return null;
 		}
 
diff --git a/wp-includes/rest-api/endpoints/class-wp-rest-autosaves-controller.php b/wp-includes/rest-api/endpoints/class-wp-rest-autosaves-controller.php
index e74c328ee8..6b2da40eb3 100644
--- a/wp-includes/rest-api/endpoints/class-wp-rest-autosaves-controller.php
+++ b/wp-includes/rest-api/endpoints/class-wp-rest-autosaves-controller.php
@@ -304,7 +304,7 @@ class WP_REST_Autosaves_Controller extends WP_REST_Revisions_Controller {
 		$revisions = wp_get_post_revisions( $parent_id, array( 'check_enabled' => false ) );
 
 		foreach ( $revisions as $revision ) {
-			if ( false !== strpos( $revision->post_name, "{$parent_id}-autosave" ) ) {
+			if ( str_contains( $revision->post_name, "{$parent_id}-autosave" ) ) {
 				$data       = $this->prepare_item_for_response( $revision, $request );
 				$response[] = $this->prepare_response_for_collection( $data );
 			}
diff --git a/wp-includes/rest-api/endpoints/class-wp-rest-plugins-controller.php b/wp-includes/rest-api/endpoints/class-wp-rest-plugins-controller.php
index 9e9441085a..4cbc5063e9 100644
--- a/wp-includes/rest-api/endpoints/class-wp-rest-plugins-controller.php
+++ b/wp-includes/rest-api/endpoints/class-wp-rest-plugins-controller.php
@@ -298,7 +298,7 @@ class WP_REST_Plugins_Controller extends WP_REST_Controller {
 		);
 
 		if ( is_wp_error( $api ) ) {
-			if ( false !== strpos( $api->get_error_message(), 'Plugin not found.' ) ) {
+			if ( str_contains( $api->get_error_message(), 'Plugin not found.' ) ) {
 				$api->add_data( array( 'status' => 404 ) );
 			} else {
 				$api->add_data( array( 'status' => 500 ) );
@@ -809,7 +809,7 @@ class WP_REST_Plugins_Controller extends WP_REST_Controller {
 			$matched_search = false;
 
 			foreach ( $item as $field ) {
-				if ( is_string( $field ) && false !== strpos( strip_tags( $field ), $search ) ) {
+				if ( is_string( $field ) && str_contains( strip_tags( $field ), $search ) ) {
 					$matched_search = true;
 					break;
 				}
diff --git a/wp-includes/rest-api/endpoints/class-wp-rest-users-controller.php b/wp-includes/rest-api/endpoints/class-wp-rest-users-controller.php
index aaa4c1a3aa..ce1b995008 100644
--- a/wp-includes/rest-api/endpoints/class-wp-rest-users-controller.php
+++ b/wp-includes/rest-api/endpoints/class-wp-rest-users-controller.php
@@ -1305,7 +1305,7 @@ class WP_REST_Users_Controller extends WP_REST_Controller {
 			);
 		}
 
-		if ( false !== strpos( $password, '\\' ) ) {
+		if ( str_contains( $password, '\\' ) ) {
 			return new WP_Error(
 				'rest_user_invalid_password',
 				sprintf(
diff --git a/wp-includes/revision.php b/wp-includes/revision.php
index b4ecf0c863..901f489ac4 100644
--- a/wp-includes/revision.php
+++ b/wp-includes/revision.php
@@ -138,7 +138,7 @@ function wp_save_post_revision( $post_id ) {
 	if ( $revisions ) {
 		// Grab the latest revision, but not an autosave.
 		foreach ( $revisions as $revision ) {
-			if ( false !== strpos( $revision->post_name, "{$revision->post_parent}-revision" ) ) {
+			if ( str_contains( $revision->post_name, "{$revision->post_parent}-revision" ) ) {
 				$latest_revision = $revision;
 				break;
 			}
@@ -223,7 +223,7 @@ function wp_save_post_revision( $post_id ) {
 	$revisions = array_slice( $revisions, 0, $delete );
 
 	for ( $i = 0; isset( $revisions[ $i ] ); $i++ ) {
-		if ( false !== strpos( $revisions[ $i ]->post_name, 'autosave' ) ) {
+		if ( str_contains( $revisions[ $i ]->post_name, 'autosave' ) ) {
 			continue;
 		}
 
@@ -313,7 +313,7 @@ function wp_is_post_autosave( $post ) {
 		return false;
 	}
 
-	if ( false !== strpos( $post->post_name, "{$post->post_parent}-autosave" ) ) {
+	if ( str_contains( $post->post_name, "{$post->post_parent}-autosave" ) ) {
 		return (int) $post->post_parent;
 	}
 
diff --git a/wp-includes/rewrite.php b/wp-includes/rewrite.php
index 2b0a5e2528..1198e520ff 100644
--- a/wp-includes/rewrite.php
+++ b/wp-includes/rewrite.php
@@ -542,12 +542,12 @@ function url_to_postid( $url ) {
 	$url    = set_url_scheme( $url, $scheme );
 
 	// Add 'www.' if it is absent and should be there.
-	if ( false !== strpos( home_url(), '://www.' ) && false === strpos( $url, '://www.' ) ) {
+	if ( str_contains( home_url(), '://www.' ) && ! str_contains( $url, '://www.' ) ) {
 		$url = str_replace( '://', '://www.', $url );
 	}
 
 	// Strip 'www.' if it is present and shouldn't be.
-	if ( false === strpos( home_url(), '://www.' ) ) {
+	if ( ! str_contains( home_url(), '://www.' ) ) {
 		$url = str_replace( '://www.', '://', $url );
 	}
 
@@ -572,7 +572,7 @@ function url_to_postid( $url ) {
 		$url = str_replace( $wp_rewrite->index . '/', '', $url );
 	}
 
-	if ( false !== strpos( trailingslashit( $url ), home_url( '/' ) ) ) {
+	if ( str_contains( trailingslashit( $url ), home_url( '/' ) ) ) {
 		// Chop off http://domain.com/[path].
 		$url = str_replace( home_url(), '', $url );
 	} else {
diff --git a/wp-includes/script-loader.php b/wp-includes/script-loader.php
index d104598d3f..fa0c2856a1 100644
--- a/wp-includes/script-loader.php
+++ b/wp-includes/script-loader.php
@@ -651,7 +651,7 @@ function wp_scripts_get_suffix( $type = '' ) {
 		// Include an unmodified $wp_version.
 		require ABSPATH . WPINC . '/version.php';
 
-		$develop_src = false !== strpos( $wp_version, '-src' );
+		$develop_src = str_contains( $wp_version, '-src' );
 
 		if ( ! defined( 'SCRIPT_DEBUG' ) ) {
 			define( 'SCRIPT_DEBUG', $develop_src );
@@ -1480,7 +1480,7 @@ function wp_default_styles( $styles ) {
 	require ABSPATH . WPINC . '/version.php';
 
 	if ( ! defined( 'SCRIPT_DEBUG' ) ) {
-		define( 'SCRIPT_DEBUG', false !== strpos( $wp_version, '-src' ) );
+		define( 'SCRIPT_DEBUG', str_contains( $wp_version, '-src' ) );
 	}
 
 	$guessurl = site_url();
diff --git a/wp-includes/shortcodes.php b/wp-includes/shortcodes.php
index cff41ed0f7..d4e874fd74 100644
--- a/wp-includes/shortcodes.php
+++ b/wp-includes/shortcodes.php
@@ -147,7 +147,7 @@ function shortcode_exists( $tag ) {
  * @return bool Whether the passed content contains the given shortcode.
  */
 function has_shortcode( $content, $tag ) {
-	if ( false === strpos( $content, '[' ) ) {
+	if ( ! str_contains( $content, '[' ) ) {
 		return false;
 	}
 
@@ -205,7 +205,7 @@ function apply_shortcodes( $content, $ignore_html = false ) {
 function do_shortcode( $content, $ignore_html = false ) {
 	global $shortcode_tags;
 
-	if ( false === strpos( $content, '[' ) ) {
+	if ( ! str_contains( $content, '[' ) ) {
 		return $content;
 	}
 
@@ -412,8 +412,8 @@ function do_shortcodes_in_html_tags( $content, $ignore_html, $tagnames ) {
 			continue;
 		}
 
-		$noopen  = false === strpos( $element, '[' );
-		$noclose = false === strpos( $element, ']' );
+		$noopen  = ! str_contains( $element, '[' );
+		$noclose = ! str_contains( $element, ']' );
 		if ( $noopen || $noclose ) {
 			// This element does not contain shortcodes.
 			if ( $noopen xor $noclose ) {
@@ -559,7 +559,7 @@ function shortcode_parse_atts( $text ) {
 
 		// Reject any unclosed HTML elements.
 		foreach ( $atts as &$value ) {
-			if ( false !== strpos( $value, '<' ) ) {
+			if ( str_contains( $value, '<' ) ) {
 				if ( 1 !== preg_match( '/^[^<]*+(?:<[^>]*+>[^<]*+)*+$/', $value ) ) {
 					$value = '';
 				}
@@ -634,7 +634,7 @@ function shortcode_atts( $pairs, $atts, $shortcode = '' ) {
 function strip_shortcodes( $content ) {
 	global $shortcode_tags;
 
-	if ( false === strpos( $content, '[' ) ) {
+	if ( ! str_contains( $content, '[' ) ) {
 		return $content;
 	}
 
diff --git a/wp-includes/template.php b/wp-includes/template.php
index f071881d49..6d89f2a23a 100644
--- a/wp-includes/template.php
+++ b/wp-includes/template.php
@@ -662,7 +662,7 @@ function get_attachment_template() {
 	$templates = array();
 
 	if ( $attachment ) {
-		if ( false !== strpos( $attachment->post_mime_type, '/' ) ) {
+		if ( str_contains( $attachment->post_mime_type, '/' ) ) {
 			list( $type, $subtype ) = explode( '/', $attachment->post_mime_type );
 		} else {
 			list( $type, $subtype ) = array( $attachment->post_mime_type, '' );
diff --git a/wp-includes/user.php b/wp-includes/user.php
index 8453c22a80..29f5fee48b 100644
--- a/wp-includes/user.php
+++ b/wp-includes/user.php
@@ -1765,7 +1765,7 @@ function sanitize_user_field( $field, $value, $user_id, $context ) {
 		return $value;
 	}
 
-	$prefixed = false !== strpos( $field, 'user_' );
+	$prefixed = str_contains( $field, 'user_' );
 
 	if ( 'edit' === $context ) {
 		if ( $prefixed ) {
@@ -2989,7 +2989,7 @@ function check_password_reset_key( $key, $login ) {
 	 */
 	$expiration_duration = apply_filters( 'password_reset_expiration', DAY_IN_SECONDS );
 
-	if ( false !== strpos( $user->user_activation_key, ':' ) ) {
+	if ( str_contains( $user->user_activation_key, ':' ) ) {
 		list( $pass_request_time, $pass_key ) = explode( ':', $user->user_activation_key, 2 );
 		$expiration_time                      = $pass_request_time + $expiration_duration;
 	} else {
diff --git a/wp-includes/vars.php b/wp-includes/vars.php
index d810851031..ce599440d5 100644
--- a/wp-includes/vars.php
+++ b/wp-includes/vars.php
@@ -65,9 +65,9 @@ $is_iphone = false;
 $is_edge   = false;
 
 if ( isset( $_SERVER['HTTP_USER_AGENT'] ) ) {
-	if ( strpos( $_SERVER['HTTP_USER_AGENT'], 'Lynx' ) !== false ) {
+	if ( str_contains( $_SERVER['HTTP_USER_AGENT'], 'Lynx' ) ) {
 		$is_lynx = true;
-	} elseif ( strpos( $_SERVER['HTTP_USER_AGENT'], 'Edg' ) !== false ) {
+	} elseif ( str_contains( $_SERVER['HTTP_USER_AGENT'], 'Edg' ) ) {
 		$is_edge = true;
 	} elseif ( stripos( $_SERVER['HTTP_USER_AGENT'], 'chrome' ) !== false ) {
 		if ( stripos( $_SERVER['HTTP_USER_AGENT'], 'chromeframe' ) !== false ) {
@@ -89,15 +89,15 @@ if ( isset( $_SERVER['HTTP_USER_AGENT'] ) ) {
 		}
 	} elseif ( stripos( $_SERVER['HTTP_USER_AGENT'], 'safari' ) !== false ) {
 		$is_safari = true;
-	} elseif ( ( strpos( $_SERVER['HTTP_USER_AGENT'], 'MSIE' ) !== false || strpos( $_SERVER['HTTP_USER_AGENT'], 'Trident' ) !== false ) && strpos( $_SERVER['HTTP_USER_AGENT'], 'Win' ) !== false ) {
+	} elseif ( ( str_contains( $_SERVER['HTTP_USER_AGENT'], 'MSIE' ) || str_contains( $_SERVER['HTTP_USER_AGENT'], 'Trident' ) ) && str_contains( $_SERVER['HTTP_USER_AGENT'], 'Win' ) ) {
 		$is_winIE = true;
-	} elseif ( strpos( $_SERVER['HTTP_USER_AGENT'], 'MSIE' ) !== false && strpos( $_SERVER['HTTP_USER_AGENT'], 'Mac' ) !== false ) {
+	} elseif ( str_contains( $_SERVER['HTTP_USER_AGENT'], 'MSIE' ) && str_contains( $_SERVER['HTTP_USER_AGENT'], 'Mac' ) ) {
 		$is_macIE = true;
-	} elseif ( strpos( $_SERVER['HTTP_USER_AGENT'], 'Gecko' ) !== false ) {
+	} elseif ( str_contains( $_SERVER['HTTP_USER_AGENT'], 'Gecko' ) ) {
 		$is_gecko = true;
-	} elseif ( strpos( $_SERVER['HTTP_USER_AGENT'], 'Opera' ) !== false ) {
+	} elseif ( str_contains( $_SERVER['HTTP_USER_AGENT'], 'Opera' ) ) {
 		$is_opera = true;
-	} elseif ( strpos( $_SERVER['HTTP_USER_AGENT'], 'Nav' ) !== false && strpos( $_SERVER['HTTP_USER_AGENT'], 'Mozilla/4.' ) !== false ) {
+	} elseif ( str_contains( $_SERVER['HTTP_USER_AGENT'], 'Nav' ) && str_contains( $_SERVER['HTTP_USER_AGENT'], 'Mozilla/4.' ) ) {
 		$is_NS4 = true;
 	}
 }
@@ -115,21 +115,21 @@ $is_IE = ( $is_macIE || $is_winIE );
  *
  * @global bool $is_apache
  */
-$is_apache = ( strpos( $_SERVER['SERVER_SOFTWARE'], 'Apache' ) !== false || strpos( $_SERVER['SERVER_SOFTWARE'], 'LiteSpeed' ) !== false );
+$is_apache = ( str_contains( $_SERVER['SERVER_SOFTWARE'], 'Apache' ) || str_contains( $_SERVER['SERVER_SOFTWARE'], 'LiteSpeed' ) );
 
 /**
  * Whether the server software is Nginx or something else
  *
  * @global bool $is_nginx
  */
-$is_nginx = ( strpos( $_SERVER['SERVER_SOFTWARE'], 'nginx' ) !== false );
+$is_nginx = ( str_contains( $_SERVER['SERVER_SOFTWARE'], 'nginx' ) );
 
 /**
  * Whether the server software is IIS or something else
  *
  * @global bool $is_IIS
  */
-$is_IIS = ! $is_apache && ( strpos( $_SERVER['SERVER_SOFTWARE'], 'Microsoft-IIS' ) !== false || strpos( $_SERVER['SERVER_SOFTWARE'], 'ExpressionDevServer' ) !== false );
+$is_IIS = ! $is_apache && ( str_contains( $_SERVER['SERVER_SOFTWARE'], 'Microsoft-IIS' ) || str_contains( $_SERVER['SERVER_SOFTWARE'], 'ExpressionDevServer' ) );
 
 /**
  * Whether the server software is IIS 7.X or greater
@@ -148,13 +148,13 @@ $is_iis7 = $is_IIS && (int) substr( $_SERVER['SERVER_SOFTWARE'], strpos( $_SERVE
 function wp_is_mobile() {
 	if ( empty( $_SERVER['HTTP_USER_AGENT'] ) ) {
 		$is_mobile = false;
-	} elseif ( strpos( $_SERVER['HTTP_USER_AGENT'], 'Mobile' ) !== false // Many mobile devices (all iPhone, iPad, etc.)
-		|| strpos( $_SERVER['HTTP_USER_AGENT'], 'Android' ) !== false
-		|| strpos( $_SERVER['HTTP_USER_AGENT'], 'Silk/' ) !== false
-		|| strpos( $_SERVER['HTTP_USER_AGENT'], 'Kindle' ) !== false
-		|| strpos( $_SERVER['HTTP_USER_AGENT'], 'BlackBerry' ) !== false
-		|| strpos( $_SERVER['HTTP_USER_AGENT'], 'Opera Mini' ) !== false
-		|| strpos( $_SERVER['HTTP_USER_AGENT'], 'Opera Mobi' ) !== false ) {
+	} elseif ( str_contains( $_SERVER['HTTP_USER_AGENT'], 'Mobile' ) // Many mobile devices (all iPhone, iPad, etc.)
+		|| str_contains( $_SERVER['HTTP_USER_AGENT'], 'Android' )
+		|| str_contains( $_SERVER['HTTP_USER_AGENT'], 'Silk/' )
+		|| str_contains( $_SERVER['HTTP_USER_AGENT'], 'Kindle' )
+		|| str_contains( $_SERVER['HTTP_USER_AGENT'], 'BlackBerry' )
+		|| str_contains( $_SERVER['HTTP_USER_AGENT'], 'Opera Mini' )
+		|| str_contains( $_SERVER['HTTP_USER_AGENT'], 'Opera Mobi' ) ) {
 			$is_mobile = true;
 	} else {
 		$is_mobile = false;
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 435d15ed3b..bd7edb724c 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.3-alpha-55987';
+$wp_version = '6.3-alpha-55988';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.
diff --git a/wp-includes/widgets/class-wp-widget-text.php b/wp-includes/widgets/class-wp-widget-text.php
index c0409e8ff5..fcf41acbf1 100644
--- a/wp-includes/widgets/class-wp-widget-text.php
+++ b/wp-includes/widgets/class-wp-widget-text.php
@@ -101,7 +101,7 @@ class WP_Widget_Text extends WP_Widget {
 		}
 
 		$wpautop         = ! empty( $instance['filter'] );
-		$has_line_breaks = ( false !== strpos( trim( $instance['text'] ), "\n" ) );
+		$has_line_breaks = ( str_contains( trim( $instance['text'] ), "\n" ) );
 
 		// If auto-paragraphs are not enabled and there are line breaks, then ensure legacy mode.
 		if ( ! $wpautop && $has_line_breaks ) {
@@ -109,7 +109,7 @@ class WP_Widget_Text extends WP_Widget {
 		}
 
 		// If an HTML comment is present, assume legacy mode.
-		if ( false !== strpos( $instance['text'], '<!--' ) ) {
+		if ( str_contains( $instance['text'], '<!--' ) ) {
 			return true;
 		}
 
diff --git a/wp-load.php b/wp-load.php
index f418118f7f..32056f1121 100644
--- a/wp-load.php
+++ b/wp-load.php
@@ -69,7 +69,7 @@ if ( file_exists( ABSPATH . 'wp-config.php' ) ) {
 	$path = wp_guess_url() . '/wp-admin/setup-config.php';
 
 	// Redirect to setup-config.php.
-	if ( false === strpos( $_SERVER['REQUEST_URI'], 'setup-config' ) ) {
+	if ( ! str_contains( $_SERVER['REQUEST_URI'], 'setup-config' ) ) {
 		header( 'Location: ' . $path );
 		exit;
 	}
diff --git a/wp-login.php b/wp-login.php
index 67d7db07a5..932a6a1144 100644
--- a/wp-login.php
+++ b/wp-login.php
@@ -1229,7 +1229,7 @@ switch ( $action ) {
 		if ( isset( $_REQUEST['redirect_to'] ) ) {
 			$redirect_to = $_REQUEST['redirect_to'];
 			// Redirect to HTTPS if user wants SSL.
-			if ( $secure_cookie && false !== strpos( $redirect_to, 'wp-admin' ) ) {
+			if ( $secure_cookie && str_contains( $redirect_to, 'wp-admin' ) ) {
 				$redirect_to = preg_replace( '|^http://|', 'https://', $redirect_to );
 			}
 		} else {
@@ -1366,7 +1366,7 @@ switch ( $action ) {
 				$errors->add( 'updated', __( '<strong>You have successfully updated WordPress!</strong> Please log back in to see what&#8217;s new.' ), 'message' );
 			} elseif ( WP_Recovery_Mode_Link_Service::LOGIN_ACTION_ENTERED === $action ) {
 				$errors->add( 'enter_recovery_mode', __( 'Recovery Mode Initialized. Please log in to continue.' ), 'message' );
-			} elseif ( isset( $_GET['redirect_to'] ) && false !== strpos( $_GET['redirect_to'], 'wp-admin/authorize-application.php' ) ) {
+			} elseif ( isset( $_GET['redirect_to'] ) && str_contains( $_GET['redirect_to'], 'wp-admin/authorize-application.php' ) ) {
 				$query_component = wp_parse_url( $_GET['redirect_to'], PHP_URL_QUERY );
 				$query           = array();
 				if ( $query_component ) {
diff --git a/wp-mail.php b/wp-mail.php
index 2600521e38..1dd1e570d1 100644
--- a/wp-mail.php
+++ b/wp-mail.php
@@ -107,7 +107,7 @@ for ( $i = 1; $i <= $count; $i++ ) {
 				$content_transfer_encoding = explode( ';', $content_transfer_encoding );
 				$content_transfer_encoding = $content_transfer_encoding[0];
 			}
-			if ( ( 'multipart/alternative' === $content_type ) && ( false !== strpos( $line, 'boundary="' ) ) && ( '' === $boundary ) ) {
+			if ( ( 'multipart/alternative' === $content_type ) && ( str_contains( $line, 'boundary="' ) ) && ( '' === $boundary ) ) {
 				$boundary = trim( $line );
 				$boundary = explode( '"', $boundary );
 				$boundary = $boundary[1];
diff --git a/wp-trackback.php b/wp-trackback.php
index 1e4ec3c993..670d9c457b 100644
--- a/wp-trackback.php
+++ b/wp-trackback.php
@@ -65,7 +65,7 @@ if ( $charset ) {
 }
 
 // No valid uses for UTF-7.
-if ( false !== strpos( $charset, 'UTF-7' ) ) {
+if ( str_contains( $charset, 'UTF-7' ) ) {
 	die;
 }