🔎 Search Terms

class
this
object spread syntax
type inference

🕗 Version & Regression Information

The issue occurs in 5.8.3, as well as the oldest version the Playground supports (3.3.3) and the current nightly version in the Playground.

⏯ Playground Link

https://www.typescriptlang.org/play/?target=10&module=7&ts=5.8.3#code/MYGwhgzhAEAuCmFbQN4ChrQA4FcBGIAlsNAGaHwgAmAggFzQB2OAtnvAE4DcG2+RJcpSoAhBszacevYAHtGSDjmCxZHABRhxrdhwA00PNskcAlKl6ZYAC0IQAdEOo1oAXmhgemK7YdPRboZe0AC+aLy4BMQe6qbGuhbe0BzwsDgcjNAAjMFhEfzRhCxYHLJYnACSjKSc8IzA8LGJ3gD0LdBFJWWcIACeHdWcKVRwsobw0AAGNnaTltByCsgAXoEo0PabMzAh0kkpaRnQy7nhmJEC2KXlHFU1KfWN5uhJi0jQAI6BjPAA7nCIWDqLIGABMpmCmDaV26HD6A3uw1G4ym6389CYOikZAo1DEmJMXFCc1e8neq3c6029nU2w8MFgvXKslIn3MuzO3gO6UyJ14YRCQA

💻 Code

class test {
  public fieldA: number;
  public fieldB: number;

  constructor(a: number, b: number) {
    this.fieldA = a;
    this.fieldB = b;
  }

  public a(): number {
    return 1;
  }

  public improperInference() {
    // improperly inferred to be `this`
    const z = { ...this };

    return z;
  }

  public properInference() {
    const q = new test(1, 2);
    // properly inferred to be `{ fieldA: number; fieldB: number; }`
    const z = { ...(this as typeof q) };

    return z;
  }
}

🙁 Actual behavior

const z = { ...this } is inferred to be this

🙂 Expected behavior

const z = { ...this } should be inferred to be a POJO with fields matching the public fields of the class.
(Actually it should also infer the protected and private fields. They're accessible from this and so should be visible at this point.)

Additional information about the issue

No response