Extends a Class will make losing and corrupted types in a child class.

[jonlepage]

When we add types on properties base class, if a child class extends this base class, we will lost types and get corrupted behavior.
Actually is seem affected by keyof T, i not tested all others types, but this one make coruptions.
From what i understand, the child class seem ignore the type from parent !
Or maybe i miss understand the logic here ? if you have alternative to suggest ?

sample js:

const TypesEnum = {
	abc: 'abc',
	abcd: 'abcd',
	abcde: 'abcde',
};

export class Base {
	/**@type {keyof TypesEnum} - all work fine here, default null for the example purpose */
	_test = null;
	constructor(data) {}
}

export class A extends Base {
       /** type are corrupted with vscode Intelisence , we should see and allowed to use the result of keyof TypesEnum ! */
	_test = 'abc'; //lint a error and we lost intellisense in Vscode (ctrl+space)!
	constructor(data) {
		super();
	}
}

🙁 Actual behavior

we lost intellisence in Vscode ! and type become corupted.

🙂 Expected behavior

type keyof should be heritate in the child class !

Without write again /**@type {keyof TypesEnum} */ in the child class !

---

tsc versions: 4.1.3 and 4.2.0-dev.20210128
Version : 1.52.1 (user setup)
Commit : ea3859d4ba2f3e577a159bc91e3074c5d85c0523
Date : 2020-12-16T16:34:46.910Z
Electron : 9.3.5
Chrome : 83.0.4103.122
Node.js : 12.14.1
V8 : 8.3.110.13-electron.0
OS : Windows_NT x64 10.0.19042

[MartinJohns]

Duplicate of #10570.

[jonlepage]

Duplicate of #10570.

i may use bad word for search thanks , i close
also : #36165
#10570
#15660
#2000