Use null coalescing operator instead of isset() in if/else statements

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

@@ -311,11 +311,7 @@ function get_cli_args( $param, $required = false ) {
 			$parts = explode( '=', $match[1] );
 			$key   = preg_replace( '/[^a-z0-9]+/', '', $parts[0] );
 
-			if ( isset( $parts[1] ) ) {
-				$out[ $key ] = $parts[1];
-			} else {
-				$out[ $key ] = true;
-			}
+			$out[ $key ] = $parts[1] ?? true;
 
 			$last_arg = $key;
 		} elseif ( (bool) preg_match( '/^-([a-zA-Z0-9]+)/', $args[ $i ], $match ) ) {

src/wp-admin/includes/post.php

@@ -122,11 +122,7 @@ function _wp_translate_postdata( $update = false, $post_data = null ) {
 		$post_data['post_status'] = 'pending';
 	}
 
-	if ( isset( $post_data['ID'] ) ) {
-		$post_id = $post_data['ID'];
-	} else {
-		$post_id = false;
-	}
+	$post_id         = $post_data['ID'] ?? false;
 	$previous_status = $post_id ? get_post_field( 'post_status', $post_id ) : false;
 
 	if ( isset( $post_data['post_status'] ) && 'private' === $post_data['post_status'] && ! current_user_can( $ptype->cap->publish_posts ) ) {

src/wp-admin/includes/template.php

@@ -2296,12 +2296,7 @@ function _post_states( $post, $display = true ) {
  */
 function get_post_states( $post ) {
 	$post_states = array();
-
-	if ( isset( $_REQUEST['post_status'] ) ) {
-		$post_status = $_REQUEST['post_status'];
-	} else {
-		$post_status = '';
-	}
+	$post_status = $_REQUEST['post_status'] ?? '';
 
 	if ( ! empty( $post->post_password ) ) {
 		$post_states['protected'] = _x( 'Password protected', 'post status' );

src/wp-admin/includes/theme.php

@@ -400,11 +400,7 @@ function get_theme_feature_list( $api = true ) {
 		$wporg_features[ $feature_category ] = array();
 
 		foreach ( $feature_items as $feature ) {
-			if ( isset( $features[ $feature_category ][ $feature ] ) ) {
-				$wporg_features[ $feature_category ][ $feature ] = $features[ $feature_category ][ $feature ];
-			} else {
-				$wporg_features[ $feature_category ][ $feature ] = $feature;
-			}
+			$wporg_features[ $feature_category ][ $feature ] = $features[ $feature_category ][ $feature ] ?? $feature;
 		}
 	}
 

src/wp-admin/upgrade.php

@@ -23,11 +23,7 @@
 
 delete_site_transient( 'update_core' );
 
-if ( isset( $_GET['step'] ) ) {
-	$step = $_GET['step'];
-} else {
-	$step = 0;
-}
+$step = $_GET['step'] ?? 0;
 
 // Do it. No output.
 if ( 'upgrade_db' === $step ) {

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

@@ -208,11 +208,7 @@ public function sanitize_query( $queries, $parent_query = null ) {
 				continue;
 			}
 
-			if ( isset( $parent_query[ $dkey ] ) ) {
-				$queries[ $dkey ] = $parent_query[ $dkey ];
-			} else {
-				$queries[ $dkey ] = $dvalue;
-			}
+			$queries[ $dkey ] = $parent_query[ $dkey ] ?? $dvalue;
 		}
 
 		// Validate the dates passed in the query.

src/wp-includes/class-wp-http-streams.php

@@ -77,11 +77,7 @@ public function request( $url, $args = array() ) {
 		}
 
 		if ( isset( $parsed_args['headers']['Host'] ) || isset( $parsed_args['headers']['host'] ) ) {
-			if ( isset( $parsed_args['headers']['Host'] ) ) {
-				$parsed_url['host'] = $parsed_args['headers']['Host'];
-			} else {
-				$parsed_url['host'] = $parsed_args['headers']['host'];
-			}
+			$parsed_url['host'] = $parsed_args['headers']['Host'] ?? $parsed_args['headers']['host'];
 			unset( $parsed_args['headers']['Host'], $parsed_args['headers']['host'] );
 		}
 

src/wp-includes/class-wp-post-type.php

@@ -655,11 +655,7 @@ public function set_props( $args ) {
 				$args['rewrite']['feeds'] = (bool) $args['has_archive'];
 			}
 			if ( ! isset( $args['rewrite']['ep_mask'] ) ) {
-				if ( isset( $args['permalink_epmask'] ) ) {
-					$args['rewrite']['ep_mask'] = $args['permalink_epmask'];
-				} else {
-					$args['rewrite']['ep_mask'] = EP_PERMALINK;
-				}
+				$args['rewrite']['ep_mask'] = $args['permalink_epmask'] ?? EP_PERMALINK;
 			}
 		}
 

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

@@ -178,11 +178,7 @@ public function do_item( $handle, $group = false ) {
 			}
 		}
 
-		if ( isset( $obj->args ) ) {
-			$media = $obj->args;
-		} else {
-			$media = 'all';
-		}
+		$media = $obj->args ?? 'all';
 
 		// A single item may alias a set of items, by having dependencies, but no source.
 		if ( ! $src ) {

src/wp-includes/class-wp-xmlrpc-server.php

@@ -3673,11 +3673,7 @@ public function wp_getComments( $args ) {
 		/** This action is documented in wp-includes/class-wp-xmlrpc-server.php */
 		do_action( 'xmlrpc_call', 'wp.getComments', $args, $this );
 
-		if ( isset( $struct['status'] ) ) {
-			$status = $struct['status'];
-		} else {
-			$status = '';
-		}
+		$status = $struct['status'] ?? '';
 
 		if ( ! current_user_can( 'moderate_comments' ) && 'approve' !== $status ) {
 			return new IXR_Error( 401, __( 'Invalid comment status.' ) );

src/wp-includes/general-template.php

@@ -1873,11 +1873,7 @@ function get_the_post_type_description() {
 	$post_type_obj = get_post_type_object( $post_type );
 
 	// Check if a description is set.
-	if ( isset( $post_type_obj->description ) ) {
-		$description = $post_type_obj->description;
-	} else {
-		$description = '';
-	}
+	$description = $post_type_obj->description ?? '';
 
 	/**
 	 * Filters the description for a post type archive.

src/wp-includes/media.php

@@ -6036,11 +6036,7 @@ function wp_get_loading_optimization_attributes( $tag_name, $attr, $context ) {
 	 * conflicting `decoding` attribute already present.
 	 */
 	if ( 'img' === $tag_name ) {
-		if ( isset( $attr['decoding'] ) ) {
-			$loading_attrs['decoding'] = $attr['decoding'];
-		} else {
-			$loading_attrs['decoding'] = 'async';
-		}
+		$loading_attrs['decoding'] = $attr['decoding'] ?? 'async';
 	}
 
 	// For any resources, width and height must be provided, to avoid layout shifts.

src/wp-includes/meta.php

@@ -674,11 +674,7 @@ function get_metadata_raw( $meta_type, $object_id, $meta_key = '', $single = fal
 
 	if ( ! $meta_cache ) {
 		$meta_cache = update_meta_cache( $meta_type, array( $object_id ) );
-		if ( isset( $meta_cache[ $object_id ] ) ) {
-			$meta_cache = $meta_cache[ $object_id ];
-		} else {
-			$meta_cache = null;
-		}
+		$meta_cache = $meta_cache[ $object_id ] ?? null;
 	}
 
 	if ( ! $meta_key ) {

src/wp-includes/rest-api/class-wp-rest-server.php

@@ -364,11 +364,7 @@ public function serve_request( $path = null ) {
 		}
 
 		if ( empty( $path ) ) {
-			if ( isset( $_SERVER['PATH_INFO'] ) ) {
-				$path = $_SERVER['PATH_INFO'];
-			} else {
-				$path = '/';
-			}
+			$path = $_SERVER['PATH_INFO'] ?? '/';
 		}
 
 		$request = new WP_REST_Request( $_SERVER['REQUEST_METHOD'], $path );

src/wp-includes/theme.php

@@ -1529,17 +1529,12 @@ function get_uploaded_header_images() {
 		$header_data  = wp_get_attachment_metadata( $header->ID );
 		$header_index = $header->ID;
 
-		$header_images[ $header_index ]                  = array();
-		$header_images[ $header_index ]['attachment_id'] = $header->ID;
-		$header_images[ $header_index ]['url']           = $url;
-		$header_images[ $header_index ]['thumbnail_url'] = $url;
-		$header_images[ $header_index ]['alt_text']      = get_post_meta( $header->ID, '_wp_attachment_image_alt', true );
-
-		if ( isset( $header_data['attachment_parent'] ) ) {
-			$header_images[ $header_index ]['attachment_parent'] = $header_data['attachment_parent'];
-		} else {
-			$header_images[ $header_index ]['attachment_parent'] = '';
-		}
+		$header_images[ $header_index ]                      = array();
+		$header_images[ $header_index ]['attachment_id']     = $header->ID;
+		$header_images[ $header_index ]['url']               = $url;
+		$header_images[ $header_index ]['thumbnail_url']     = $url;
+		$header_images[ $header_index ]['alt_text']          = get_post_meta( $header->ID, '_wp_attachment_image_alt', true );
+		$header_images[ $header_index ]['attachment_parent'] = $header_data['attachment_parent'] ?? '';
 
 		if ( isset( $header_data['width'] ) ) {
 			$header_images[ $header_index ]['width'] = $header_data['width'];