discriminatedUnion produces TS error when .default or .preprocess are applied

[RobertCraigie]

Playground link.

Given this snippet:

import { z } from 'zod';

const FooSchema = z.object({
  type: z.literal('foo').default('foo'),
  a: z.string(),
});

const BarSchema = z.object({
  type: z.literal('custom'),
  method: z.string(),
});

const BazSchema = z.discriminatedUnion('type', [FooSchema, BarSchema]);
console.log(BazSchema.parse({ a: 'foo' }));

TypeScript produces this error:

$ tsc tmp.ts
tmp.ts:13:49 - error TS2322: Type 'ZodObject<{ type: ZodDefault<ZodLiteral<"foo">>; a: ZodString; }, "strip", ZodTypeAny, { type?: "foo"; a?: string; }, { type?: "foo"; a?: string; }>' is not assignable to type 'ZodDiscriminatedUnionOption<"type", Primitive>'.
  Type '{ type: z.ZodDefault<z.ZodLiteral<"foo">>; a: z.ZodString; }' is not assignable to type '{ type: ZodLiteral<Primitive>; } & ZodRawShape'.
    Type '{ type: z.ZodDefault<z.ZodLiteral<"foo">>; a: z.ZodString; }' is not assignable to type '{ type: ZodLiteral<Primitive>; }'.
      Types of property 'type' are incompatible.
        Property 'value' is missing in type 'ZodDefault<ZodLiteral<"foo">>' but required in type 'ZodLiteral<Primitive>'.

13 const BazSchema = z.discriminatedUnion('type', [FooSchema, BarSchema]);
                                                   ~~~~~~~~~

  node_modules/zod/lib/types.d.ts:531:9
    531     get value(): T;
                ~~~~~
    'value' is declared here.


Found 1 error in tmp.ts:13

This code works at runtime however and Zod correctly parses the object:

{ type: 'foo', a: 'foo' }

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[RobertCraigie]

Bump for stale bot - I'd still like to have this feature.