Repository: colinhacks/zod (ts)

Issue:
v4: toJSONSchema Circular sibling references
I'm so sorry for this one but I'll blame @jedwards1211 for dropping this into my unit tests for Zod 3 😆 

```ts
import z, { type ZodType, toJSONSchema } from 'zod';

const BasePost = z.object({
  id: z.string(),
  userId: z.string(),
});

type Post = z.infer<typeof BasePost> & {
  user?: User;
};

const BaseUser = z.object({
  id: z.string(),
});

type User = z.infer<typeof BaseUser> & {
  posts?: Post[];
};

const PostSchema: ZodType<Post> = BasePost.extend({
  user: z.lazy(() => UserSchema).optional(),
}).meta({ id: 'post' });

const PostArray = z.array(z.lazy(() => PostSchema));

const UserSchema: ZodType<User> = z
  .lazy(() =>
    BaseUser.extend({
      posts: PostArray.optional(),
      comments: PostArray.optional(),
    }),
  )
  .meta({ id: 'user' });

const Schema = z.object({
  user: UserSchema,
});

toJSONSchema(Schema, {
  reused: 'ref',
});
```

Currently throws `ReferenceError: Cannot access 'UserSchema' before initialization`

It looks like when I substitute out all the `z.lazy()` syntax for the new `getter` syntax it seems to be all happy which I'm for the record okay with doing.



Pull request description:
Defer initialization to avoid crashes with z.lazy. Closes #4324.

Patch:
diff --git a/packages/zod/src/v4/core/schemas.ts b/packages/zod/src/v4/core/schemas.ts
index 19754c2e..57342e68 100644
--- a/packages/zod/src/v4/core/schemas.ts
+++ b/packages/zod/src/v4/core/schemas.ts
@@ -2896,7 +2896,7 @@ export interface $ZodOptionalInternals<T extends $ZodType = $ZodType>
   optionality: "optional";
   isst: never;
   values: T["_zod"]["values"];
-  pattern: RegExp;
+  pattern: T["_zod"]["pattern"];
 }
 
 export interface $ZodOptional<T extends $ZodType = $ZodType> extends $ZodType {
@@ -2908,10 +2908,14 @@ export const $ZodOptional: core.$constructor<$ZodOptional> = /*@__PURE__*/ core.
   (inst, def) => {
     $ZodType.init(inst, def);
     inst._zod.optionality = "optional";
-    if (def.innerType._zod.values) inst._zod.values = new Set([...def.innerType._zod.values, undefined]);
 
-    const pattern = (def.innerType as any)._zod.pattern;
-    if (pattern) inst._zod.pattern = new RegExp(`^(${util.cleanRegex(pattern.source)})?$`);
+    util.defineLazy(inst._zod, "values", () =>
+      def.innerType._zod.values ? new Set([...def.innerType._zod.values, undefined]) : undefined
+    );
+    util.defineLazy(inst._zod, "pattern", () => {
+      const pattern = def.innerType._zod.pattern;
+      return pattern ? new RegExp(`^(${util.cleanRegex(pattern.source)})?$`) : undefined;
+    });
 
     inst._zod.parse = (payload, ctx) => {
       if (payload.value === undefined) {
@@ -2940,7 +2944,7 @@ export interface $ZodNullableInternals<T extends $ZodType = $ZodType>
   optionality: T["_zod"]["optionality"];
   isst: never;
   values: T["_zod"]["values"];
-  pattern: RegExp;
+  pattern: T["_zod"]["pattern"];
 }
 
 export interface $ZodNullable<T extends $ZodType = $ZodType> extends $ZodType {
@@ -2951,12 +2955,16 @@ export const $ZodNullable: core.$constructor<$ZodNullable> = /*@__PURE__*/ core.
   "$ZodNullable",
   (inst, def) => {
     $ZodType.init(inst, def);
-    inst._zod.optionality = def.innerType._zod.optionality;
+    util.defineLazy(inst._zod, "optionality", () => def.innerType._zod.optionality);
 
-    const pattern = (def.innerType as any)._zod.pattern;
-    if (pattern) inst._zod.pattern = new RegExp(`^(${util.cleanRegex(pattern.source)}|null)$`);
+    util.defineLazy(inst._zod, "pattern", () => {
+      const pattern = def.innerType._zod.pattern;
+      return pattern ? new RegExp(`^(${util.cleanRegex(pattern.source)}|null)$`) : undefined;
+    });
 
-    if (def.innerType._zod.values) inst._zod.values = new Set([...def.innerType._zod.values, null]);
+    util.defineLazy(inst._zod, "values", () => {
+      return def.innerType._zod.values ? new Set([...def.innerType._zod.values, null]) : undefined;
+    });
 
     inst._zod.parse = (payload, ctx) => {
       if (payload.value === null) return payload;
@@ -3000,7 +3008,7 @@ export const $ZodDefault: core.$constructor<$ZodDefault> = /*@__PURE__*/ core.$c
 
     // inst._zod.qin = "true";
     inst._zod.optionality = "defaulted";
-    inst._zod.values = def.innerType._zod.values;
+    util.defineLazy(inst._zod, "values", () => def.innerType._zod.values);
 
     inst._zod.parse = (payload, ctx) => {
       if (payload.value === undefined) {
@@ -3059,7 +3067,7 @@ export const $ZodPrefault: core.$constructor<$ZodPrefault> = /*@__PURE__*/ core.
     $ZodType.init(inst, def);
 
     inst._zod.optionality = "defaulted";
-    inst._zod.values = def.innerType._zod.values;
+    util.defineLazy(inst._zod, "values", () => def.innerType._zod.values);
 
     inst._zod.parse = (payload, ctx) => {
       if (payload.value === undefined) {
@@ -3097,8 +3105,12 @@ export const $ZodNonOptional: core.$constructor<$ZodNonOptional> = /*@__PURE__*/
   "$ZodNonOptional",
   (inst, def) => {
     $ZodType.init(inst, def);
-    if (def.innerType._zod.values)
-      inst._zod.values = new Set([...def.innerType._zod.values].filter((x) => x !== undefined));
+
+    util.defineLazy(inst._zod, "values", () => {
+      const v = def.innerType._zod.values;
+      return v ? new Set([...v].filter((x) => x !== undefined)) : undefined;
+    });
+
     inst._zod.parse = (payload, ctx) => {
       const result = def.innerType._zod.run(payload, ctx);
       if (result instanceof Promise) {
@@ -3237,8 +3249,8 @@ export interface $ZodCatch<T extends $ZodType = $ZodType> extends $ZodType {
 
 export const $ZodCatch: core.$constructor<$ZodCatch> = /*@__PURE__*/ core.$constructor("$ZodCatch", (inst, def) => {
   $ZodType.init(inst, def);
-  inst._zod.optionality = def.innerType._zod.optionality;
-  inst._zod.values = def.innerType._zod.values;
+  util.defineLazy(inst._zod, "optionality", () => def.innerType._zod.optionality);
+  util.defineLazy(inst._zod, "values", () => def.innerType._zod.values);
 
   inst._zod.parse = (payload, ctx) => {
     const result = def.innerType._zod.run(payload, ctx);
@@ -3392,7 +3404,7 @@ export const $ZodReadonly: core.$constructor<$ZodReadonly> = /*@__PURE__*/ core.
   (inst, def) => {
     $ZodType.init(inst, def);
     util.defineLazy(inst._zod, "disc", () => def.innerType._zod.disc);
-    inst._zod.optionality = def.innerType._zod.optionality;
+    util.defineLazy(inst._zod, "optionality", () => def.innerType._zod.optionality);
 
     inst._zod.parse = (payload, ctx) => {
       const result = def.innerType._zod.run(payload, ctx);
diff --git a/play.ts b/play.ts
index ab8f7e24..33d94938 100644
--- a/play.ts
+++ b/play.ts
@@ -1,3 +1,11 @@
 import * as z from "zod/v4";
 
 z;
+
+const a: any = z.lazy(() => a).optional();
+const b: any = z.lazy(() => b).nullable();
+const c: any = z.lazy(() => c).default({} as any);
+const d: any = z.lazy(() => d).prefault({} as any);
+const e: any = z.lazy(() => e).nonoptional();
+const f: any = z.lazy(() => f).catch({} as any);
+const g: any = z.lazy(() => z.object({ g })).readonly();


Test patch:
diff --git a/packages/zod/src/v4/classic/tests/lazy.test.ts b/packages/zod/src/v4/classic/tests/lazy.test.ts
index 0910859d..b9a9422d 100644
--- a/packages/zod/src/v4/classic/tests/lazy.test.ts
+++ b/packages/zod/src/v4/classic/tests/lazy.test.ts
@@ -200,3 +200,13 @@ test("complicated self-recursion", () => {
 
   type _Category = z.output<typeof Category>;
 });
+
+test("lazy initialization", () => {
+  const a: any = z.lazy(() => a).optional();
+  const b: any = z.lazy(() => b).nullable();
+  const c: any = z.lazy(() => c).default({} as any);
+  const d: any = z.lazy(() => d).prefault({} as any);
+  const e: any = z.lazy(() => e).nonoptional();
+  const f: any = z.lazy(() => f).catch({} as any);
+  const g: any = z.lazy(() => z.object({ g })).readonly();
+});