MC-35649: Admin Login Unusable on PHP 7.4 Due to PHP Notices

Author: fascinosum

lib/internal/Magento/Framework/View/Element/Html/Calendar.php

@@ -107,20 +107,7 @@ protected function _toHtml()
             ]
         );
 
-        /**
-         * Get "today" and "week" words
-         *
-         * Fields value in the current position have been added to ICU Data tables,
-         * starting with ICU library version 51.1.
-         * Due to fact that we do not use these variables in templates, we do not initialize them for older versions
-         *
-         * @see https://github.com/unicode-org/icu/blob/release-50-2/icu4c/source/data/locales/en.txt
-         * @see https://github.com/unicode-org/icu/blob/release-51-2/icu4c/source/data/locales/en.txt
-         */
-        if ($localeData->get('fields')) {
-            $this->assign('today', $this->encoder->encode($localeData['fields']['day']['relative']['0']));
-            $this->assign('week', $this->encoder->encode($localeData['fields']['week']['dn']));
-        }
+        $this->assignFieldsValues($localeData);
 
         // get "am" & "pm" words
         $this->assign('am', $this->encoder->encode($localeData['calendar']['gregorian']['AmPmMarkers']['0']));
@@ -200,4 +187,25 @@ public function getYearRange()
         return (new \DateTime())->modify('- 100 years')->format('Y')
             . ':' . (new \DateTime())->modify('+ 100 years')->format('Y');
     }
+
+    /**
+     * Assign "fields" values from the ICU data
+     *
+     * @param \ResourceBundle $localeData
+     */
+    private function assignFieldsValues(\ResourceBundle $localeData): void
+    {
+        /**
+         * Fields value in the current position has been added to ICU Data tables
+         * starting with ICU library version 51.1.
+         * Due to fact that we do not use these variables in templates, we do not initialize them for older versions
+         *
+         * @see https://github.com/unicode-org/icu/blob/release-50-2/icu4c/source/data/locales/en.txt
+         * @see https://github.com/unicode-org/icu/blob/release-51-2/icu4c/source/data/locales/en.txt
+         */
+        if ($localeData->get('fields')) {
+            $this->assign('today', $this->encoder->encode($localeData['fields']['day']['relative']['0']));
+            $this->assign('week', $this->encoder->encode($localeData['fields']['week']['dn']));
+        }
+    }
 }