license import { Directive , Input } from '@angular/core' ; let nextUniqueId = 0 ; /** Single error message to be shown underneath the form field. */ @ Directive ( { selector : 'mat-error' , host : { 'class' : 'mat-error' , 'role' : 'alert' , '[attr.id]' : 'id' , } } ) export class MatError { @ Input ( ) id : string = `mat-error-${ nextUniqueId ++ }` ; }