Incorrect generated JS code when private (hashtag) property is used with parenthesis in left assignment

[jbl428]

Bug Report

When private (hashtag) property is used with parenthesis in left assignment, TS generate __classPrivateFieldGet, not __classPrivateFieldSet.

I think this issue is related with this one.
It should apply __classPrivateFieldSet only if there is incrementing/decrementing operations.

🔎 Search Terms

• __classPrivateFieldGet
• private property
• Invalid left-hand side in assignment

🕗 Version & Regression Information

• If compile target is ES2022, it is not an issue.
• This is the behavior in every version I tried, and I reviewed the FAQ for entries about setting private property.

⏯ Playground Link

Playground link with relevant code

💻 Code

class Temp {
  readonly #id: number;

  constructor(value: number) {
    this.#id = value;
  }

  setId(id: number) {
    (this.#id as number) = id;
    // (this.#id) = id <-- this one is also problem.
  }
}

new Temp(10).setId(20)

🙁 Actual behavior

TS generate the following code.

class Temp {
    constructor(value) {
        _Temp_id.set(this, void 0);
        __classPrivateFieldSet(this, _Temp_id, value, "f");
    }
    setId(id) {
        __classPrivateFieldGet(this, _Temp_id, "f") = id; // it will throw error `Invalid left-hand side in assignment`
    }
}

🙂 Expected behavior

TS should generate the following code.

class Temp {
    constructor(value) {
        _Temp_id.set(this, void 0);
        __classPrivateFieldSet(this, _Temp_id, value, "f");
    }
    setId(id) {
        __classPrivateFieldSet(this, _Temp_id, id, "f");
    }
}

[fatcerberus]

Random aside, I’m not sure I’d describe these as “hashtag properties” any more than I’d describe a bear as a fat dog

[rbuckton]

Random aside, I’m not sure I’d describe these as “hashtag properties” any more than I’d describe a bear as a fat dog

Common parlance in TC39 is to call them "private elements".

[DanielRosenwasser]

Thanks @a-tarasyuk!