fix(module:date-picker): restrict the date when it overflows at the m…

…onth panel

close NG-ZORRO#1899

components/date-picker/lib/candy-date/candy-date.ts

@@ -2,6 +2,7 @@ import * as addMonths from 'date-fns/add_months';
 import * as addYears from 'date-fns/add_years';
 import * as endOfMonth from 'date-fns/end_of_month';
 import * as setDay from 'date-fns/set_day';
+import * as setMonth from 'date-fns/set_month';
 // import * as setYear from 'date-fns/set_year';
 import { firstDayOfWeek } from './util';
 
@@ -108,10 +109,12 @@ export class CandyDate {
   }
 
   // NOTE: month starts from 0
+  // NOTE: Don't use the native API for month manipulation as it not restrict the date when it overflows, eg. (new Date('2018-7-31')).setMonth(1) will be date of 2018-3-03 instead of 2018-2-28
   setMonth(month: number): CandyDate {
-    const date = new Date(this.nativeDate);
-    date.setMonth(month);
-    return new CandyDate(date);
+    // const date = new Date(this.nativeDate);
+    // date.setMonth(month);
+    // return new CandyDate(date);
+    return new CandyDate(setMonth(this.nativeDate, month));
   }
 
   addMonths(amount: number): CandyDate {