Missing `Date` variant in types of too small/big errors

[gebsh]

Interfaces $ZodIssueTooSmall and $ZodIssueTooBig type minimum and maximum properties respectively as number | bigint:

zod/packages/zod/src/v4/core/errors.ts

Lines 26 to 44 in 3b94610

	export interface $ZodIssueTooBig<Input = unknown> extends $ZodIssueBase {
	readonly code: "too_big";
	readonly origin: "number" | "int" | "bigint" | "date" | "string" | "array" | "set" | "file" | (string & {});
	readonly maximum: number | bigint;
	readonly inclusive?: boolean;
	readonly exact?: boolean;
	readonly input?: Input;
	}
	export interface $ZodIssueTooSmall<Input = unknown> extends $ZodIssueBase {
	readonly code: "too_small";
	readonly origin: "number" | "int" | "bigint" | "date" | "string" | "array" | "set" | "file" | (string & {});
	readonly minimum: number | bigint;
	/** True if the allowable range includes the minimum */
	readonly inclusive?: boolean;
	/** True if the allowed value is fixed (e.g.` z.length(5)`), not a range (`z.minLength(5)`) */
	readonly exact?: boolean;
	readonly input?: Input;
	}

This misses the Date variant that occurs at runtime when validating z.date().min() or z.date().max():

zod/packages/zod/src/v4/core/checks.ts

Lines 64 to 68 in 3b94610

	export const $ZodCheckLessThan: core.$constructor<$ZodCheckLessThan> = /*@__PURE__*/ core.$constructor(
	"$ZodCheckLessThan",
	(inst, def) => {
	$ZodCheck.init(inst, def);
	const origin = numericOriginMap[typeof def.value as "number" | "bigint" | "object"];

zod/packages/zod/src/v4/core/checks.ts

Lines 55 to 59 in 3b94610

	const numericOriginMap = {
	number: "number",
	bigint: "bigint",
	object: "date",
	} as const;

For example, running the following code logs Date despite issue.minimum being typed as number | bigint:

import * as z from "zod";

const schema = z.date().min(new Date("2025-01-01"));
const result = schema.safeParse(new Date("2020"), {
	error: (issue) => {
		if (issue.code === "too_small") {
			console.log(issue.minimum.constructor.name);
		}

		return "";
	},
});

[dosubot]

Hi @gebsh! I'm Dosu and I’m helping the zod team.

You're right—there's a type mismatch here. The $ZodIssueTooSmall and $ZodIssueTooBig interfaces currently type minimum and maximum as number | bigint, but at runtime, these can be Date objects when validating with z.date().min() or .max() source. The code that generates these issues for date schemas sets these properties to a Date instance, and there's no comment or documentation indicating this is intentional—it looks like an oversight source.

As a workaround, you can use a type assertion or a custom type guard when handling these issues, or extend the interface locally to include Date. Tagging @colinhacks for visibility—if a PR to fix the type would be welcome, let us know!

If this answers your question or the workaround is sufficient, feel free to close the issue.

To reply, just mention @dosu.

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