import type { DurationUnit } from "./durationUnit";
/**
 * Returns the difference between two dates in the given unit, truncated toward zero.
 * Calendar-aware for "M" (months) and "y" (years).
 *
 * @param {Date} left - End date
 * @param {Date} right - Start date
 * @param {DurationUnit} unit - Unit of the result
 * @returns {number} The difference, truncated toward zero
 * @example
 * diff(new Date("2025-12-31"), new Date("2025-01-01"), "d"); // 364
 * diff(new Date("2026-01-01"), new Date("2025-01-01"), "y"); // 1
 */
export declare const diff: (left: Date, right: Date, unit: DurationUnit) => number;