Bug: Defining schema shape causes a TS error when it shouldn't

[lounging-lizard]

Description

When defining the schema shape using a type (const Schema: z.ZodType<MyType> = ...) Typescript is raises an error when using a schema and the pipe method.

I believe it to be a bug as the correct type is inferred from the schema.

Example

Zod Version 3.23.8

import { z } from "zod";

export const StringListSchema = z.string().transform((input) => input?.split(","));

export type InputType = {
  strings?: string[];
};

const Schema: z.ZodType<InputType> = z.object({
  strings: StringListSchema.pipe(z.array(z.string())).optional(),
});
// Type Error: Type 'string | undefined' is not assignable to type 'string[] | undefined'.

export type OutputType = z.infer<typeof Schema>;
// Infered Type: type OutputType = { strings?: string[] | undefined; }

console.log(Schema.parse({ strings: "one,two" }));
// Output: { strings: [ 'one', 'two' ] }

[lounging-lizard]

My apologies, I had not noticed that the inferred input type was in fact the issue, and the bug was due to my misunderstanding.

If anybody comes across this it is because the input component of z.ZodType is inferred from the output component of the generic.