fix(material/datepicker): prevent crash during range picker navigation

Author: Mr-KRAMA

src/material/datepicker/calendar-body.html

@@ -14,7 +14,7 @@
 }
 
 <!-- Create the first row separately so we can include a special spacer cell. -->
-@for (row of rows; track _trackRow(row); let rowIndex = $index) {
+@for (row of rows; track _trackRow($index, row); let rowIndex = $index) {
   <tr role="row">
     <!--
       This cell is purely decorative, but we can't put `aria-hidden` or `role="presentation"` on it,

src/material/datepicker/calendar-body.ts

@@ -221,7 +221,11 @@ export class MatCalendarBody<D = any> implements OnChanges, OnDestroy, AfterView
    * key on the row, but that would require a breaking change for the `rows` input. We don't
    * use the built-in identity tracking, because it logs warnings.
    */
-  _trackRow = (row: MatCalendarCell[]) => row;
+  _trackRow = (index: number, row: MatCalendarCell[]) => {
+    // Use a combination of index and first cell value for more stable tracking
+    // This prevents LView detachment errors when navigating between months
+    return row.length > 0 ? `${index}-${row[0].value}` : index;
+  };
 
   constructor(...args: unknown[]);
 

src/material/datepicker/month-view.spec.ts

@@ -353,6 +353,29 @@ describe('MatMonthView', () => {
             expect(calendarInstance.date).toEqual(new Date(2017, JAN, 19));
           });
 
+          it('should not crash when navigating to next month with down arrow in range mode', () => {
+            // Set up a range selection to reproduce the bug scenario
+            testComponent.selected = new DateRange(new Date(2017, JAN, 15), null);
+            fixture.changeDetectorRef.markForCheck();
+            fixture.detectChanges();
+
+            // Navigate to a date near the end of the month
+            calendarInstance.date = new Date(2017, JAN, 28);
+            fixture.changeDetectorRef.markForCheck();
+            fixture.detectChanges();
+
+            // This should trigger month navigation and test the fix for the LView detachment error
+            expect(() => {
+              for (let i = 0; i < 10; i++) {
+                dispatchKeyboardEvent(calendarBodyEl, 'keydown', DOWN_ARROW);
+                fixture.detectChanges();
+              }
+            }).not.toThrow();
+
+            // Verify we navigated to the next month
+            expect(calendarInstance.date.getMonth()).toBe(FEB);
+          });
+
           it('should go to beginning of the month on home press', () => {
             dispatchKeyboardEvent(calendarBodyEl, 'keydown', HOME);
             fixture.detectChanges();