React's ComponentProps type issues in TypeScript 5.6.2 about typescript HOT 11 OPEN

additional repro:

function withP3<P>(p: P) {
  const m =
    <I,>(from: I) =>
    <I2,>(from2: I2) => ({ ...from, ...from2, ...p });
  return createTransform(m);
}

const addP3 = withP3({ a: 1 });
const addedSome3 = addP3({ b: '' });
const added3 = addedSome3({ c: true });

const addP3_other = withP3({ foo: 'bar' });
const addedSome3_other = addP3_other({ qwerty: 123 });
const added3_other = addedSome3_other({ bazinga: true });

We can see here { a: number } leaking from the first "chain" of instantiations into the second "chain".

I have a fix for both here: #59972 :)

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Result2 is not correct. It leaks T and that shouldn't happen. It's the other result that is correct, you can double-check that on 5.4 by checking the types resolved based on the result of your custom forwardRef call and based on the results of "the same" inlined type (I copy-pasted its computed definition): TS playground

As we can see here, all 4 results are:

type Result = Omit<any, "ref"> & {
    className?: string | undefined;
    as?: ElementType | undefined;
} & {
    ref?: Ref<HTMLElement> | undefined;
}

If we now switch this playground to 5.6.2 then we'll see one of those going rogue (the one that you assumed is correct): TS playground

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A reasonable self-isolated repro: TS playground

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Huh, interesting. Thank you for the investigation.

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`` ceb4951646b978c517240e7bf43517a53d969c25

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We'd really need a much shorter repro to be able to prioritize this

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Great job as usual, thank you @Andarist!

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1

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Vv

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