Support function for locator-based validators (#30528)

Allow a function to be passed as the reference to the ref helper and the
requiredIf, requiredUnless and sameAs validators.

types/vuelidate/lib/validators.d.ts

@@ -23,7 +23,7 @@ export type CustomRule = (value: any, parentVm?: Vue) => boolean
 export interface Helpers {
     withParams(params: Params, rule: CustomRule): ValidationRule
     req(value: any): ValidationRule
-    ref(reference: string, vm: any, parentVm?: Vue): any
+    ref(reference: string | ((vm: any, parentVm?: Vue) => any), vm: any, parentVm?: Vue): any
     len(value: any): number
     regex(type: string, expr: RegExp): ValidationRule
 }
@@ -32,8 +32,8 @@ export const helpers: Helpers
 
 // pre-defined rules
 export function required(): ValidationRule
-export function requiredIf(field: string): ValidationRule
-export function requiredUnless(field: string): ValidationRule
+export function requiredIf(field: string | ((vm: any, parentVm?: Vue) => any)): ValidationRule
+export function requiredUnless(field: string | ((vm: any, parentVm?: Vue) => any)): ValidationRule
 export function minLength(length: number): ValidationRule
 export function maxLength(length: number): ValidationRule
 export function minValue(min: number): ValidationRule
@@ -45,7 +45,7 @@ export function numeric(): ValidationRule
 export function email(): ValidationRule
 export function ipAddress(): ValidationRule
 export function macAddress(): ValidationRule
-export function sameAs(field: string): ValidationRule
+export function sameAs(field: string | ((vm: any, parentVm?: Vue) => any)): ValidationRule
 export function url(): ValidationRule
 export function or(...validators: ValidationRule[]): ValidationRule
 export function and(...validators: ValidationRule[]): ValidationRule

types/vuelidate/vuelidate-tests.ts

@@ -45,7 +45,8 @@ const mustHaveLength = (minLen: number) => helpers.withParams(
         },
         repeatPassword: {
             sameAsPassword: sameAs('password'),
-            mustBeSame: mustBeSame('password')
+            mustBeSame: mustBeSame('password'),
+            sameAsPassword2: sameAs(vm => vm.password)
         },
         form: {
             nestedA: {