| 1 |  |  | <?php | 
            
                                                                                                            
                            
            
                                    
            
            
                | 2 |  |  | /** | 
            
                                                                                                            
                            
            
                                    
            
            
                | 3 |  |  |  * Handles CSS output for dimensions fields. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 4 |  |  |  * | 
            
                                                                                                            
                            
            
                                    
            
            
                | 5 |  |  |  * @package     Kirki | 
            
                                                                                                            
                            
            
                                    
            
            
                | 6 |  |  |  * @subpackage  Controls | 
            
                                                                                                            
                            
            
                                    
            
            
                | 7 |  |  |  * @copyright   Copyright (c) 2017, Aristeides Stathopoulos | 
            
                                                                                                            
                            
            
                                    
            
            
                | 8 |  |  |  * @license     http://opensource.org/licenses/https://opensource.org/licenses/MIT | 
            
                                                                                                            
                            
            
                                    
            
            
                | 9 |  |  |  * @since       2.2.0 | 
            
                                                                                                            
                            
            
                                    
            
            
                | 10 |  |  |  */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 11 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 12 |  |  | /** | 
            
                                                                                                            
                            
            
                                    
            
            
                | 13 |  |  |  * Output overrides. | 
            
                                                                                                            
                                                                
            
                                    
            
            
                | 14 |  |  |  */ | 
            
                                                                        
                            
            
                                    
            
            
                | 15 |  |  | class Kirki_Output_Field_Dimensions extends Kirki_Output { | 
            
                                                                        
                            
            
                                    
            
            
                | 16 |  |  |  | 
            
                                                                        
                            
            
                                    
            
            
                | 17 |  |  | 	/** | 
            
                                                                        
                            
            
                                    
            
            
                | 18 |  |  | 	 * Processes a single item from the `output` array. | 
            
                                                                        
                            
            
                                    
            
            
                | 19 |  |  | 	 * | 
            
                                                                        
                            
            
                                    
            
            
                | 20 |  |  | 	 * @access protected | 
            
                                                                        
                            
            
                                    
            
            
                | 21 |  |  | 	 * @param array $output The `output` item. | 
            
                                                                        
                            
            
                                    
            
            
                | 22 |  |  | 	 * @param array $value  The field's value. | 
            
                                                                        
                            
            
                                    
            
            
                | 23 |  |  | 	 */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 24 |  |  | 	protected function process_output( $output, $value ) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 25 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 26 |  |  | 		$output = wp_parse_args( $output, array( | 
            
                                                                                                            
                            
            
                                    
            
            
                | 27 |  |  | 			'element'     => '', | 
            
                                                                                                            
                            
            
                                    
            
            
                | 28 |  |  | 			'property'    => '', | 
            
                                                                                                            
                            
            
                                    
            
            
                | 29 |  |  | 			'media_query' => 'global', | 
            
                                                                                                            
                            
            
                                    
            
            
                | 30 |  |  | 			'prefix'      => '', | 
            
                                                                                                            
                            
            
                                    
            
            
                | 31 |  |  | 			'suffix'      => '', | 
            
                                                                                                            
                            
            
                                    
            
            
                | 32 |  |  | 		) ); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 33 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 34 |  |  | 		if ( is_array( $value ) ) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 35 |  |  | 			foreach ( $value as $key => $sub_value ) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 36 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 37 |  |  | 				$property = ( empty( $output['property'] ) ) ? $key : $output['property'] . '-' . $key; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 38 |  |  | 				if ( isset( $output['choice'] ) && $output['property'] ) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 39 |  |  | 					if ( $key === $output['choice'] ) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 40 |  |  | 						$property = $output['property']; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 41 |  |  | 					} else { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 42 |  |  | 						continue; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 43 |  |  | 					} | 
            
                                                                                                            
                            
            
                                    
            
            
                | 44 |  |  | 				} | 
            
                                                                                                            
                            
            
                                    
            
            
                | 45 |  |  | 				if ( false !== strpos( $output['property'], '%%' ) ) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 46 |  |  | 					$property = str_replace( '%%', $key, $output['property'] ); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 47 |  |  | 				} | 
            
                                                                                                            
                            
            
                                    
            
            
                | 48 |  |  | 				$this->styles[ $output['media_query'] ][ $output['element'] ][ $property ] = $output['prefix'] . $this->process_property_value( $property, $value[ $key ] ) . $output['suffix']; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 49 |  |  | 			} | 
            
                                                                                                            
                            
            
                                    
            
            
                | 50 |  |  | 		} elseif ( isset( $output['choice'] ) ) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 51 |  |  | 			if ( false !== strpos( $output['property'], '%%' ) ) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 52 |  |  | 				$output['property'] = str_replace( '%%', $key, $output['property'] ); | 
                            
                    |  |  |  | 
                                                                                        
                                                                                     | 
            
                                                                                                            
                            
            
                                    
            
            
                | 53 |  |  | 			} | 
            
                                                                                                            
                            
            
                                    
            
            
                | 54 |  |  | 			$this->styles[ $output['media_query'] ][ $output['element'] ][ $output['property'] ] = $output['prefix'] . $this->process_property_value( $output['property'], $value ) . $output['suffix']; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 55 |  |  | 		} | 
            
                                                                                                            
                                                                
            
                                    
            
            
                | 56 |  |  | 	} | 
            
                                                        
            
                                    
            
            
                | 57 |  |  | } | 
            
                                                        
            
                                    
            
            
                | 58 |  |  |  | 
            
                        
This error can happen if you refactor code and forget to move the variable initialization.
Let’s take a look at a simple example:
The above code is perfectly fine. Now imagine that we re-order the statements:
In that case,
$xwould be read before it is initialized. This was a very basic example, however the principle is the same for the found issue.