`typeof this` => `this` throw "`Cannot find name 'this'.(2304)`" for no reason

[Malix-Labs]

Bug Report

🔎 Search Terms

this, typeof this, Cannot find name 'this', 2304

🕗 Version & Regression Information

• This is the behavior in every version I tried, and I reviewed the FAQ for entries

⏯ Playground Link

Playground link with relevant code

💻 Code

export class A {
	x = 1
	a(x: typeof this.x): void {}
//        ^         ^^^^ Cannot find name 'this'.(2304)
//        L_____________ `x` has proper type inference nevertheless

}

const a = new A().a(1)

🙁 Actual behavior

Throw a wrong error

🙂 Expected behavior

To not throw this error

[MartinJohns]

typeof is used to get the type of values, but this is no value in that position, it's a type. You want to write this["x"] instead.

[somebody1234]

@MartinJohns note that it doesn't error if you remove the last line though

[whzx5byb]

Note that this is a regression between 4.8.4 and 4.9.5 (and also 4.7.4 and 4.8.4).

4.7.4:
Always throw error.

4.8.4:
No error.

4.9.5:
Throw error only with the last line.