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I don't really know if this is possible, but here's what I have

PaymentEntity is a class

type CardPaymentEntity = SetRequired<PaymentEntity, 'processor'>;

  static fromPayment(payment: CardPaymentEntity, opt: FromPayment): PaymentAuthorizationEntity {
    return new PaymentAuthorizationEntity(
      payment.amount,
      payment.currency,
      payment, // compile error here, because CardPaymentEntity is not a PaymentEntity class

Argument of type '{ readonly status: PaymentStatus; readonly amount: number; readonly currency: Currency; readonly orderId: string; readonly methodType: PaymentMethodType; ... 8 more ...; readonly processor: Processor | null; }' is not assignable to parameter of type 'PaymentEntity'.

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Why should it return the original type of it's a class?

well, perhaps I should not say the exact original type, but because the type changed to just a shape it no longer matched the class type for typescript, even though the only thing I wanted to do was make the processor field required at that point. AFAIK, a required field should be possible to pass into an optional field. Again, don't know if this is actually possible.

Hmm, I see your point for SetRequired. If a type T is expected somewhere, passing SetRequired<T, 'whatever'> should also work. However I disagree with SetOptional and Except, because the new type would not fulfill the original "interface contract".

ok, makes sense, just off the cuff those seemed like they should do the same last night. But after some sleep, you're right.

@xenoterracide That said, I tried to create a small snippet to reproduce the problem but couldn't. I declared a class X and a function expecting X, then declared a variable with type SetRequired<X, 'foo'> and I could pass it to my function without any compiler error...

Can you please modify this playground code I created to show the issue?

I've got to be honest, right now I have no idea what I was doing last night that I created this issue, it was probably stupidly complex.

however, you might want to take a look at the playground, I'm actually surprised that it compiles given that the required field can be null | undefined

ahah! got it, the SetRequired you pasted is not the same as the released version... or there's something else going on with it

playground

import { Except, SetRequired } from 'type-fest';

type FooRequired = SetRequired<X, 'foo' | 'bar' | 'baz'>;

class X {
  foo?: string;
  bar!: string | null;
  baz: undefined;
  private _createdAt = '';
}

function x1(x: X): void {
  x;
}

function x2(x: FooRequired): void {
  x1(x);
}

const a: FooRequired = {
  foo: 'true',
  bar: null,
  baz: undefined,
};

x2(a); // No error!

type BarExclude = Except<FooRequired, '_createdAt'>;

the actual problem seems to be private properties, also, you'll note that even though they're SetRequired bar and baz can still be set to null and undefined, this isn't what I would expect.

I seem to get one more compile error locally than on ts playground.

app-lib/graph/packages/app/src/payment/model/dal/test.ts:17:6 - error TS2345: Argument of type '{ foo: string; bar: string | null; baz: undefined; }' is not assignable to parameter of type 'X'.
  Property '_createdAt' is missing in type '{ foo: string; bar: string | null; baz: undefined; }' but required in type 'X'.

17   x1(x);
        ~

  app-lib/graph/packages/app/src/payment/model/dal/test.ts:9:11
    9   private _createdAt = '';
                ~~~~~~~~~~
    '_createdAt' is declared here.

app-lib/graph/packages/app/src/payment/model/dal/test.ts:28:39 - error TS2344: Type '"_createdAt"' does not satisfy the constraint '"foo" | "bar" | "baz"'.

28 type BarExclude = Except<FooRequired, '_createdAt'>;
                                         ~~~~~~~~~~~~

[10:41:44 PM] Found 3 errors. Watching for file changes.