Fix ZodType assignability issues

colinhacks · colinhacks · commit 6be478b98c6a · 2025-05-31T18:44:27.000-07:00
diff --git a/packages/zod/src/v4/classic/tests/object.test.ts b/packages/zod/src/v4/classic/tests/object.test.ts
@@ -503,3 +503,17 @@ test("empty shape", () => {
   expect(() => a.parse([])).toThrow();
   expect(() => a.parse([], { jitless: true })).toThrow();
 });
+
+test("zodtype assignability", () => {
+  // Does not error
+  z.object({ hello: z.string().optional() }) satisfies z.ZodType<{ hello?: string | undefined }>;
+  z.object({ hello: z.string() }) satisfies z.ZodType<{ hello?: string | undefined }>;
+  // @ts-expect-error
+  z.object({}) satisfies z.ZodType<{ hello: string | undefined }>;
+  // @ts-expect-error
+  z.object({ hello: z.string().optional() }) satisfies z.ZodType<{ hello: string | undefined }>;
+  // @ts-expect-error
+  z.object({ hello: z.string().optional() }) satisfies z.ZodType<{ hello: string }>;
+  // @ts-expect-error
+  z.object({ hello: z.number() }) satisfies z.ZodType<{ hello?: string | undefined }>;
+});
diff --git a/packages/zod/src/v4/core/schemas.ts b/packages/zod/src/v4/core/schemas.ts
@@ -149,17 +149,6 @@ export interface $ZodTypeInternals<out O = unknown, out I = unknown> {
   parent?: $ZodType | undefined;
 }
 
-// export interface $ZodTypeInternals<out O = unknown, out I = unknown> extends $ZodTypeInternals {
-//   // "~types": { output: O; input: I };
-//   output: O;
-//   input: I;
-// }
-
-// export interface _$ZodType {
-//   _zod: $ZodTypeInternals;
-//   "~standard": StandardSchemaV1.Props<core.input<this>, core.output<this>>;
-// }
-
 export interface $ZodType<O = unknown, I = unknown> {
   _zod: $ZodTypeInternals<O, I>;
   "~standard": StandardSchemaV1.Props<core.input<this>, core.output<this>>;
@@ -1525,7 +1514,10 @@ export interface $ZodObjectInternals<
   /** @ts-ignore Cast variance */
   out Shape extends Readonly<$ZodShape> = Readonly<$ZodShape>,
   out Config extends $ZodObjectConfig = $ZodObjectConfig,
-> extends $ZodTypeInternals<any, any> {
+> extends $ZodTypeInternals<
+    $InferObjectOutputFallback<Shape, Config["out"]>,
+    $InferObjectInputFallback<Shape, Config["in"]>
+  > {
   def: $ZodObjectDef<Shape>;
   config: Config;
   isst: errors.$ZodIssueInvalidType | errors.$ZodIssueUnrecognizedKeys;
@@ -1541,6 +1533,36 @@ export type $ZodLooseShape = Record<string, any>;
 type OptionalOutSchema = { _zod: { optout: "optional" } };
 type OptionalInSchema = { _zod: { optin: "optional" } };
 
+export type $InferObjectOutputFallback<
+  T extends $ZodLooseShape,
+  Extra extends Record<string, unknown>,
+> = string extends keyof T
+  ? object
+  : keyof (T & Extra) extends never
+    ? Record<string, never>
+    : util.Prettify<
+        {
+          // this is a simplified fallback type
+          // there is no support for key optionality
+          -readonly [k in keyof T]: core.output<T[k]>;
+        } & Extra
+      >;
+
+export type $InferObjectInputFallback<
+  T extends $ZodLooseShape,
+  Extra extends Record<string, unknown>,
+> = string extends keyof T
+  ? object
+  : keyof (T & Extra) extends never
+    ? Record<string, never>
+    : util.Prettify<
+        {
+          // this is a simplified fallback type
+          // there is no support for key optionality
+          -readonly [k in keyof T]: core.input<T[k]>;
+        } & Extra
+      >;
+
 export type $InferObjectOutput<T extends $ZodLooseShape, Extra extends Record<string, unknown>> = string extends keyof T
   ? object
   : keyof (T & Extra) extends never
diff --git a/play.ts b/play.ts
@@ -1,3 +1,3 @@
-import { z } from "zod/v4-mini";
+import { z } from "zod/v4";
 
 z;

Original file line number	Diff line number	Diff line change
`@@ -1,3 +1,3 @@`
`1`		`-import { z } from "zod/v4-mini";`
	`1`	`+import { z } from "zod/v4";`
`2`	`2`
`3`	`3`	`z;`