Readonly<T> prevents private members from being accessed

[shrinktofit]

Bug Report

🔎 Search Terms

private, readonly, remove, class, exclude

🕗 Version & Regression Information

• This is a crash
• This changed between versions ______ and _______
• This is the behavior in every version I tried, and I reviewed the FAQ for entries about _________
• I was unable to test this on prior versions because _______

⏯ Playground Link

Playground link with relevant code

💻 Code

class Foo {
    public bar = 0;
    private _bar = 0;
    #bar = 0;

    public baz(that: Foo, readonlyThat: Readonly<Foo>) {
        this.bar; // OK
        this._bar; // OK
        this.#bar; // OK

        that.bar; // OK
        that._bar; // OK
        that.#bar; // OK

        readonlyThat.bar; // OK
        readonlyThat._bar; // Error
        readonlyThat.#bar; // Error
    }
}

🙁 Actual behavior

Can not access private members from Readonly<T> version class, even within class body.

🙂 Expected behavior

Within Foo.baz(), all fields of objects with type Readonly<Foo> should be accessible.

[MartinJohns]

This is working as intended. Mapped types like Readonly<T> use the keyof operator, and the keyof operator intentionally does not include non-public members.

Duplicate of #16441.

[shrinktofit]

This is working as intended. Mapped types like Readonly use the keyof operator, and the keyof operator intentionally does not include non-public members.

Well. Is there any alternative way to implement "readonly class object"?

[MartinJohns]

No. You'd need something like #35416 for this.

[typescript-bot]

This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.