import type { PropOptionsGenerator } from '../types';
import type { Validator } from '../validators';
/**
 * Allows any string. No further runtime validation is performed by default.
 *
 * @template T - can be used to restrict the type at compile time with a union type.
 * @param validator - Optional function for further runtime validation; should return `undefined` if valid, or an error string if invalid.
 */
export declare const stringProp: <T extends string = string>(validator?: Validator) => PropOptionsGenerator<T>;