Constraint check resolves an un-annotated accessor while its object literal is still being inferred

The issue involves TypeScript's type inference and constraint checking in a recursive object literal with a getter. Start by examining the constraint in the array function and the Writeable mapped type. Look at the deferred type checking logic in the compiler, particularly around issue #64413. Run the provided code in the TypeScript playground to see the error, then trace through the type checker's handling of circular references and deferred nodes.

🔎 Search Terms

recursive object literal getter accessor constraint check circular "implicitly has return type" mapped type zod

🕗 Version & Regression Information

• This is the behavior in every version I tried, including [email protected] with #64311

⏯ Playground Link

No response

💻 Code

type output<T> = T extends { _zod: { output: any } } ? T["_zod"]["output"] : unknown;
type input<T> = T extends { _zod: { input: any } } ? T["_zod"]["input"] : unknown;
type NoUndefined<T> = T extends undefined ? never : T;
type Writeable<T> = { -readonly [P in keyof T]: T[P] };
type Prettify<T> = { [K in keyof T]: T[K] } & {};
interface $ZodTypeInternals<out O = unknown, out I = unknown> { def: unknown; output: O; input: I; optin?: "optional" | undefined; optout?: "optional" | undefined }
interface StandardProps<I, O> { readonly types?: { readonly input: I; readonly output: O } | undefined }
interface $ZodType<O = unknown, I = unknown, Internals extends $ZodTypeInternals<O, I> = $ZodTypeInternals<O, I>> {
  _zod: Internals;
  "~standard": StandardProps<input<this>, output<this>>;
}
interface ZodType<out Internals extends $ZodTypeInternals = $ZodTypeInternals> extends $ZodType<any, any, Internals> {
  default(def: NoUndefined<output<this>>): ZodDefault<this>;
  default(def: () => NoUndefined<output<this>>): ZodDefault<this>;
}
type Shape = Readonly<{ [k: string]: $ZodType }>;
type OptionalOut = { _zod: { optout: "optional" } };
type OptionalIn = { _zod: { optin: "optional" } };
type $InferObjectOutput<T extends Shape> = Prettify<
  { -readonly [k in keyof T as T[k] extends OptionalOut ? never : k]: T[k]["_zod"]["output"] } &
  { -readonly [k in keyof T as T[k] extends OptionalOut ? k : never]?: T[k]["_zod"]["output"] }
>;
type $InferObjectInput<T extends Shape> = Prettify<
  { -readonly [k in keyof T as T[k] extends OptionalIn ? never : k]: T[k]["_zod"]["input"] } &
  { -readonly [k in keyof T as T[k] extends OptionalIn ? k : never]?: T[k]["_zod"]["input"] }
>;
interface $ZodStringInternals extends $ZodTypeInternals { def: { type: "string" }; output: string; input: string }
interface ZodString extends ZodType<$ZodStringInternals> {}
declare function string(): ZodString;
interface $ZodObjectInternals<S extends Shape> extends $ZodTypeInternals { def: { type: "object"; shape: S }; output: $InferObjectOutput<S>; input: $InferObjectInput<S> }
interface ZodObject<S extends Shape> extends ZodType<$ZodObjectInternals<S>> { shape: S }
declare function object<T extends Shape>(shape: T): ZodObject<Writeable<T>>;
interface $ZodArrayInternals<T extends $ZodType> extends $ZodTypeInternals { def: { type: "array"; element: T }; output: output<T>[]; input: input<T>[] }
interface ZodArray<T extends $ZodType> extends ZodType<$ZodArrayInternals<T>> { element: T }
declare function array<T extends $ZodType>(element: T): ZodArray<T>;
interface $ZodDefaultInternals<T extends $ZodType> extends $ZodTypeInternals { def: { type: "default"; inner: T }; output: NoUndefined<output<T>>; input: input<T> | undefined; optin: "optional" }
interface ZodDefault<T extends $ZodType> extends ZodType<$ZodDefaultInternals<T>> {}

const Tree = object({
  name: string(),
  get children() {
    return array(Tree).default([]);
  },
});

🙁 Actual behavior

children is reported as circular, TS7023 on the getter and TS2615 in Writeable.

🙂 Expected behavior

The getter infers ZodDefault<ZodArray<typeof Tree>>, as it does when array's constraint omits output.

Additional information about the issue

The check of array's type argument against $ZodType compares _zod, whose output property instantiates Tree's inferred output type, and the mapped property of Writeable for children reads the getter while its return type is still being inferred. The same happens through the outer call when object constrains its shape to Readonly<{ [k: string]: $ZodType }>. Zod avoids both today by constraining its builders to a looser type that omits output. #64413 defers those checks until the file's deferred nodes have run.