Mixins created from `obj.constructor` cannot have members

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### 🔎 Search Terms

mixin constructor property instance

### 🕗 Version & Regression Information

- This is the behavior in every version I tried, and I reviewed the FAQ for entries about mixins

### ⏯ Playground Link

https://www.typescriptlang.org/play/?ts=5.7.3#code/C4TwDgpgBAwg9gOwM7AE4FcDGw6oDwAqAfFALxQIQDuAFAHQMCGqA5kgFxSMIgDaAugEoyJAgG4AUBMwAbRkiRQAYnDhQA3hKhQA9DqgB1XAGsuqOOgQATKAAtgwMBz0sAlsFvoARnUxwAtjr+rpjmSHAAZsA6BOAQAMqhrmDRrgroEEg6AMwAHAAsAIxaUFYQsszQvABEfshoWDio1fyc8PUY2Lh4HmlEkgC+UhGW2K6IUACyrgAergiFhFAQM8AQ1ortKJ1NeCpwREQ0SOiQqBUKnATCmtp6UADyANIlqBDA6KgIUBeKK2sbKAnM6-DQlbQRVQRGg3IbaAaDYajYDjb7TOYIABMS3+6ysin2RzgXgAVlcbiV7jA5AooAByGgAQQQiBA-gsil+gjpUHmflQb2wMhAy1WeMUXnk0FBdIIdLolP09KZLJ47PQnJpSG5vMU8iQrhYCEYXhk0BwUA80sQ20Y82AUEilri9LlABooF50A7ZTy-OgZDYvNB5ihuCjGGsbFR3LYuKVXBEIhA3ggHScvKBII6Ij8bWg7Wn6ft5a93p9vqDcYDiSTfPmdrgwdoIVCYRo4VAERIhkA

### 💻 Code

```ts
type Constructor = new(...args: any[]) => T;

class Foo {
// Work around https://github.com/microsoft/TypeScript/issues/3841
declare ["constructor"]: Constructor;
}

function Mixin1>(superclass: T) {
// OK
return class extends superclass {
foof() {}
};
}

function Mixin2(obj: T) {
// Class '(Anonymous class)' incorrectly extends base class 'T'.
// '(Anonymous class)' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint 'Foo'.
return class extends obj.constructor {
foof() {}
};
}
```

### 🙁 Actual behavior

`Mixin1` compiles fine, but `Mixin2` has an error:

```
Class '(Anonymous class)' incorrectly extends base class 'T'.
'(Anonymous class)' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint 'Foo'.
```

Removing the `foof` member causes it to compile without error.

### 🙂 Expected behavior

Both should compile fine because they are doing the same thing.

### Additional information about the issue

_No response_

Commencez par exécuter la reproduction liée dans TypeScript Playground et comparez Mixin1 avec Mixin2, en vous concentrant sur l’expression d’héritage de classe utilisant obj.constructor. L’issue est terminée lorsque Mixin2 peut conserver son membre foof sans l’erreur d’héritage signalée, tandis que Mixin1 continue de compiler.

Rédigé par le modèle d'indexation à partir du texte de l'issue.