Use null coalescing operator (#2543)

Author: sreichel

.github/phpstan-baseline.neon

@@ -3215,11 +3215,6 @@ parameters:
 			count: 1
 			path: ../app/code/core/Mage/Sales/Model/Order/Api.php
 
-		-
-			message: "#^Variable \\$data in isset\\(\\) always exists and is not nullable\\.$#"
-			count: 1
-			path: ../app/code/core/Mage/Sales/Model/Order/Creditmemo/Api.php
-
 		-
 			message: "#^Cannot call method addAttributeToFilter\\(\\) on Mage_Core_Model_Resource_Db_Collection_Abstract\\|false\\.$#"
 			count: 1

app/code/core/Mage/Admin/Model/Config.php

@@ -129,11 +129,7 @@ public function getAclAssert($name = '')
             return $asserts;
         }
 
-        if (isset($asserts->$name)) {
-            return $asserts->$name;
-        }
-
-        return false;
+        return $asserts->$name ?? false;
     }
 
     /**
@@ -149,11 +145,7 @@ public function getAclPrivilegeSet($name = '')
             return $sets;
         }
 
-        if (isset($sets->$name)) {
-            return $sets->$name;
-        }
-
-        return false;
+        return $sets->$name ?? false;
     }
 
     /**

app/code/core/Mage/Admin/Model/Observer.php

@@ -64,8 +64,8 @@ public function actionPreDispatchAdmin($observer)
 
                     if ($coreSession->validateFormKey($request->getPost("form_key"))) {
                         $postLogin = $request->getPost('login');
-                        $username = isset($postLogin['username']) ? $postLogin['username'] : '';
-                        $password = isset($postLogin['password']) ? $postLogin['password'] : '';
+                        $username = $postLogin['username'] ?? '';
+                        $password = $postLogin['password'] ?? '';
                         $session->login($username, $password, $request);
                         $request->setPost('login', null);
                     } else {

app/code/core/Mage/Admin/Model/Session.php

@@ -189,7 +189,7 @@ public function login($username, $password, $request = null)
             $this->_loginFailed($e, $request, $username, $message);
         }
 
-        return isset($user) ? $user : null;
+        return $user ?? null;
     }
 
     /**

app/code/core/Mage/AdminNotification/Helper/Data.php

@@ -65,7 +65,7 @@ public function getUnreadNoticeCount($severity)
         if (is_null($this->_unreadNoticeCounts)) {
             $this->_unreadNoticeCounts = Mage::getModel('adminnotification/inbox')->getNoticeStatus();
         }
-        return isset($this->_unreadNoticeCounts[$severity]) ? $this->_unreadNoticeCounts[$severity] : 0;
+        return $this->_unreadNoticeCounts[$severity] ?? 0;
     }
 
     /**

app/code/core/Mage/AdminNotification/Model/Inbox.php

@@ -71,10 +71,7 @@ public function getSeverities($severity = null)
         ];
 
         if (!is_null($severity)) {
-            if (isset($severities[$severity])) {
-                return $severities[$severity];
-            }
-            return null;
+            return $severities[$severity] ?? null;
         }
 
         return $severities;

app/code/core/Mage/Adminhtml/Block/Api/Tab/Rolesedit.php

@@ -64,7 +64,7 @@ public function getResTreeJson()
 
         $rootArray = $this->_getNodeJson($resources,1);
 
-        return Mage::helper('core')->jsonEncode(isset($rootArray['children']) ? $rootArray['children'] : []);
+        return Mage::helper('core')->jsonEncode($rootArray['children'] ?? []);
     }
 
     protected function _sortTree($a, $b)

app/code/core/Mage/Adminhtml/Block/Catalog/Category/Tree.php

@@ -162,13 +162,13 @@ public function getMoveUrl()
     public function getTree($parenNodeCategory=null)
     {
            $rootArray = $this->_getNodeJson($this->getRoot($parenNodeCategory));
-        return isset($rootArray['children']) ? $rootArray['children'] : [];
+        return $rootArray['children'] ?? [];
     }
 
     public function getTreeJson($parenNodeCategory=null)
     {
         $rootArray = $this->_getNodeJson($this->getRoot($parenNodeCategory));
-        return Mage::helper('core')->jsonEncode(isset($rootArray['children']) ? $rootArray['children'] : []);
+        return Mage::helper('core')->jsonEncode($rootArray['children'] ?? []);
     }
 
     /**

app/code/core/Mage/Adminhtml/Block/Catalog/Form/Renderer/Config/DateFieldsOrder.php

@@ -46,9 +46,9 @@ protected function _getElementHtml(Varien_Data_Form_Element_Abstract $element)
         }
 
         $_parts = [];
-        $_parts[] = $element->setValue(isset($values[0]) ? $values[0] : null)->getElementHtml();
-        $_parts[] = $element->setValue(isset($values[1]) ? $values[1] : null)->getElementHtml();
-        $_parts[] = $element->setValue(isset($values[2]) ? $values[2] : null)->getElementHtml();
+        $_parts[] = $element->setValue($values[0] ?? null)->getElementHtml();
+        $_parts[] = $element->setValue($values[1] ?? null)->getElementHtml();
+        $_parts[] = $element->setValue($values[2] ?? null)->getElementHtml();
 
         return implode(' <span>/</span> ', $_parts);
     }

app/code/core/Mage/Adminhtml/Block/Catalog/Form/Renderer/Config/YearRange.php

@@ -38,8 +38,8 @@ protected function _getElementHtml(Varien_Data_Form_Element_Abstract $element)
             $values = [];
         }
 
-        $from = $element->setValue(isset($values[0]) ? $values[0] : null)->getElementHtml();
-        $to = $element->setValue(isset($values[1]) ? $values[1] : null)->getElementHtml();
+        $from = $element->setValue($values[0] ?? null)->getElementHtml();
+        $to = $element->setValue($values[1] ?? null)->getElementHtml();
         return Mage::helper('adminhtml')->__('from') . ' ' . $from
             . ' '
             . Mage::helper('adminhtml')->__('to') . ' ' . $to;