Coding Standards: replace if isset() return with null coalescing.

src/wp-admin/includes/class-wp-list-table.php

@@ -344,12 +344,7 @@ public function get_pagination_arg( $key ) {
 		if ( 'page' === $key ) {
 			return $this->get_pagenum();
 		}
-
-		if ( isset( $this->_pagination_args[ $key ] ) ) {
-			return $this->_pagination_args[ $key ];
-		}
-
-		return 0;
+		return $this->_pagination_args[ $key ] ?? 0;
 	}
 
 	/**

src/wp-admin/includes/class-wp-screen.php

@@ -554,10 +554,7 @@ public function get_option( $option, $key = false ) {
 			return null;
 		}
 		if ( $key ) {
-			if ( isset( $this->_options[ $option ][ $key ] ) ) {
-				return $this->_options[ $option ][ $key ];
-			}
-			return null;
+			return $this->_options[ $option ][ $key ] ?? null;
 		}
 		return $this->_options[ $option ];
 	}

src/wp-admin/includes/file.php

@@ -1097,11 +1097,7 @@ function wp_handle_upload( &$file, $overrides = false, $time = null ) {
 	 *  $_POST['action'] must be set and its value must equal $overrides['action']
 	 *  or this:
 	 */
-	$action = 'wp_handle_upload';
-	if ( isset( $overrides['action'] ) ) {
-		$action = $overrides['action'];
-	}
-
+	$action = $overrides['action'] ?? 'wp_handle_upload';
 	return _wp_handle_upload( $file, $overrides, $time, $action );
 }
 
@@ -1128,11 +1124,7 @@ function wp_handle_sideload( &$file, $overrides = false, $time = null ) {
 	 *  $_POST['action'] must be set and its value must equal $overrides['action']
 	 *  or this:
 	 */
-	$action = 'wp_handle_sideload';
-	if ( isset( $overrides['action'] ) ) {
-		$action = $overrides['action'];
-	}
-
+	$action = $overrides['action'] ?? 'wp_handle_sideload';
 	return _wp_handle_upload( $file, $overrides, $time, $action );
 }
 

src/wp-admin/includes/plugin.php

@@ -1971,44 +1971,25 @@ function get_admin_page_parent( $parent_page = '' ) {
 		$plugin_page, $_wp_real_parent_file, $_wp_menu_nopriv, $_wp_submenu_nopriv;
 
 	if ( ! empty( $parent_page ) && 'admin.php' !== $parent_page ) {
-		if ( isset( $_wp_real_parent_file[ $parent_page ] ) ) {
-			$parent_page = $_wp_real_parent_file[ $parent_page ];
-		}
-
-		return $parent_page;
+		return $_wp_real_parent_file[ $parent_page ] ?? $parent_page;
 	}
 
 	if ( 'admin.php' === $pagenow && isset( $plugin_page ) ) {
 		foreach ( (array) $menu as $parent_menu ) {
 			if ( $parent_menu[2] === $plugin_page ) {
 				$parent_file = $plugin_page;
-
-				if ( isset( $_wp_real_parent_file[ $parent_file ] ) ) {
-					$parent_file = $_wp_real_parent_file[ $parent_file ];
-				}
-
-				return $parent_file;
+				return $_wp_real_parent_file[ $parent_file ] ?? $parent_file;
 			}
 		}
 		if ( isset( $_wp_menu_nopriv[ $plugin_page ] ) ) {
 			$parent_file = $plugin_page;
-
-			if ( isset( $_wp_real_parent_file[ $parent_file ] ) ) {
-					$parent_file = $_wp_real_parent_file[ $parent_file ];
-			}
-
-			return $parent_file;
+			return $_wp_real_parent_file[ $parent_file ] ?? $parent_file;
 		}
 	}
 
 	if ( isset( $plugin_page ) && isset( $_wp_submenu_nopriv[ $pagenow ][ $plugin_page ] ) ) {
 		$parent_file = $pagenow;
-
-		if ( isset( $_wp_real_parent_file[ $parent_file ] ) ) {
-			$parent_file = $_wp_real_parent_file[ $parent_file ];
-		}
-
-		return $parent_file;
+		return $_wp_real_parent_file[ $parent_file ] ?? $parent_file;
 	}
 
 	foreach ( array_keys( (array) $submenu ) as $parent_page ) {

src/wp-includes/class-wp-block-styles-registry.php

@@ -170,10 +170,7 @@ public function get_all_registered() {
 	 * @return array[] Array whose keys are block style names and whose values are block style properties.
 	 */
 	public function get_registered_styles_for_block( $block_name ) {
-		if ( isset( $this->registered_block_styles[ $block_name ] ) ) {
-			return $this->registered_block_styles[ $block_name ];
-		}
-		return array();
+		return $this->registered_block_styles[ $block_name ] ?? array();
 	}
 
 	/**

src/wp-includes/class-wp-comment.php

@@ -323,11 +323,7 @@ public function add_child( WP_Comment $child ) {
 	 * @return WP_Comment|false Returns the comment object if found, otherwise false.
 	 */
 	public function get_child( $child_id ) {
-		if ( isset( $this->children[ $child_id ] ) ) {
-			return $this->children[ $child_id ];
-		}
-
-		return false;
+		return $this->children[ $child_id ] ?? false;
 	}
 
 	/**

src/wp-includes/class-wp-dependencies.php

@@ -477,10 +477,7 @@ public function query( $handle, $status = 'registered' ) {
 		switch ( $status ) {
 			case 'registered':
 			case 'scripts': // Back compat.
-				if ( isset( $this->registered[ $handle ] ) ) {
-					return $this->registered[ $handle ];
-				}
-				return false;
+				return $this->registered[ $handle ] ?? false;
 
 			case 'enqueued':
 			case 'queue': // Back compat.

src/wp-includes/class-wp-plugin-dependencies.php

@@ -200,11 +200,7 @@ public static function get_dependents( $slug ) {
 	 * @return array An array of dependency plugin slugs.
 	 */
 	public static function get_dependencies( $plugin_file ) {
-		if ( isset( self::$dependencies[ $plugin_file ] ) ) {
-			return self::$dependencies[ $plugin_file ];
-		}
-
-		return array();
+		return self::$dependencies[ $plugin_file ] ?? array();
 	}
 
 	/**
@@ -354,12 +350,7 @@ public static function get_dependency_filepath( $slug ) {
 	 */
 	public static function get_dependency_data( $slug ) {
 		$dependency_api_data = self::get_dependency_api_data();
-
-		if ( isset( $dependency_api_data[ $slug ] ) ) {
-			return $dependency_api_data[ $slug ];
-		}
-
-		return false;
+		return $dependency_api_data[ $slug ] ?? false;
 	}
 
 	/**

src/wp-includes/class-wp-query.php

@@ -1860,11 +1860,7 @@ public function set_404() {
 	 * @return mixed Contents of the query variable.
 	 */
 	public function get( $query_var, $default_value = '' ) {
-		if ( isset( $this->query_vars[ $query_var ] ) ) {
-			return $this->query_vars[ $query_var ];
-		}
-
-		return $default_value;
+		return $this->query_vars[ $query_var ] ?? $default_value;
 	}
 
 	/**
@@ -4066,12 +4062,7 @@ public function get_queried_object() {
 	 */
 	public function get_queried_object_id() {
 		$this->get_queried_object();
-
-		if ( isset( $this->queried_object_id ) ) {
-			return $this->queried_object_id;
-		}
-
-		return 0;
+		return $this->queried_object_id ?? 0;
 	}
 
 	/**

src/wp-includes/class-wp-user-meta-session-tokens.php

@@ -60,12 +60,7 @@ protected function prepare_session( $session ) {
 	 */
 	protected function get_session( $verifier ) {
 		$sessions = $this->get_sessions();
-
-		if ( isset( $sessions[ $verifier ] ) ) {
-			return $sessions[ $verifier ];
-		}
-
-		return null;
+		return $sessions[ $verifier ] ?? null;
 	}
 
 	/**

src/wp-includes/class-wp-user-query.php

@@ -910,11 +910,7 @@ public function query() {
 	 * @return mixed
 	 */
 	public function get( $query_var ) {
-		if ( isset( $this->query_vars[ $query_var ] ) ) {
-			return $this->query_vars[ $query_var ];
-		}
-
-		return null;
+		return $this->query_vars[ $query_var ] ?? null;
 	}
 
 	/**

src/wp-includes/global-styles-and-settings.php

@@ -384,10 +384,7 @@ static function ( $item ) {
 			}
 		)
 	);
-	if ( isset( $result[0] ) ) {
-		return $result[0];
-	}
-	return '';
+	return $result[0] ?? '';
 }
 
 /**

src/wp-includes/http.php

@@ -266,11 +266,7 @@ function wp_remote_retrieve_header( $response, $header ) {
 		return '';
 	}
 
-	if ( isset( $response['headers'][ $header ] ) ) {
-		return $response['headers'][ $header ];
-	}
-
-	return '';
+	return $response['headers'][ $header ] ?? '';
 }
 
 /**

src/wp-includes/nav-menu.php

@@ -148,10 +148,7 @@ function register_nav_menu( $location, $description ) {
  */
 function get_registered_nav_menus() {
 	global $_wp_registered_nav_menus;
-	if ( isset( $_wp_registered_nav_menus ) ) {
-		return $_wp_registered_nav_menus;
-	}
-	return array();
+	return $_wp_registered_nav_menus ?? array();
 }
 
 /**

src/wp-includes/option.php

@@ -547,10 +547,7 @@ function wp_set_options_autoload( array $options, $autoload ) {
  */
 function wp_set_option_autoload( $option, $autoload ) {
 	$result = wp_set_option_autoload_values( array( $option => $autoload ) );
-	if ( isset( $result[ $option ] ) ) {
-		return $result[ $option ];
-	}
-	return false;
+	return $result[ $option ] ?? false;
 }
 
 /**

src/wp-includes/post.php

@@ -2322,12 +2322,7 @@ function remove_post_type_support( $post_type, $feature ) {
  */
 function get_all_post_type_supports( $post_type ) {
 	global $_wp_post_type_features;
-
-	if ( isset( $_wp_post_type_features[ $post_type ] ) ) {
-		return $_wp_post_type_features[ $post_type ];
-	}
-
-	return array();
+	return $_wp_post_type_features[ $post_type ] ?? array();
 }
 
 /**

src/wp-includes/theme.php

@@ -3042,10 +3042,7 @@ function get_theme_support( $feature, ...$args ) {
 		case 'custom-logo':
 		case 'custom-header':
 		case 'custom-background':
-			if ( isset( $_wp_theme_features[ $feature ][0][ $args[0] ] ) ) {
-				return $_wp_theme_features[ $feature ][0][ $args[0] ];
-			}
-			return false;
+			return $_wp_theme_features[ $feature ][0][ $args[0] ] ?? false;
 
 		default:
 			return $_wp_theme_features[ $feature ];