Optional subfields get marked as required with InferType

Describe the bug When when an object schema is created, it’s Typescript types are faithfully inferred via InferType, but when that same schema is included as a nested schema within another object, the resulting inferred types incorrectly drop the optional status of any nested fields.

To Reproduce

Minimal repro here: https://codesandbox.io/s/yup-infertype-nested-optional-issue-v63dd

import { object, string, InferType } from "yup";

const nameSchema = object({
  first: string().notRequired(),
  last: string().notRequired()
});

type NameType = InferType<typeof nameSchema>;

const userSchema = object({
  name: nameSchema.notRequired()
});

type UserType = InferType<typeof userSchema>;

class User implements UserType {
  name?: NameType;
}

Results in error:

Property 'name' in type 'User' is not assignable to the same property in base type 'Id<Partial<Pick<{ name: { first: ...; last: ...; }; }, "name">> & Pick<{ name: { first: ...; last: ...; }; }, never>>'.
  Type 'Id<Partial<Pick<{ first: string; last: string; }, "first" | "last">> & Pick<{ first: string; last: string; }, never>>' is not assignable to type '{ first: string; last: string; }'.
    Property 'first' is optional in type 'Id<Partial<Pick<{ first: string; last: string; }, "first" | "last">> & Pick<{ first: string; last: string; }, never>>' but required in type '{ first: string; last: string; }'.ts(2416)

Based on the hints, NameType by itself is correct:

type NameType = {
    first?: string;
    last?: string;
}

but once included in UserType, the optionals get dropped:

type UserType = {
    name?: {
        first: string;
        last: string;
    };
}

Expected behavior Optional state of fields is preserved for tested schemas

Platform (please complete the following information):

• Browser [e.g. chrome]
• Version [e.g. 83]

[taschmidt]

Now that yup comes with its own types, I’m seeing this issue again:

[taschmidt]

I think I just worked around it. @jquense maybe time to reopen this?