Polymorphic `this` breaks when a module exports a variable and interface with the same name

Importing a variable that has a corresponding interface of the same name from a module causes unexpected behavior.

In the screenshot below, the function, doSomething, should return the type Model<number> due to polymorphic this; however, it returns Model<T>, which is unusable.

Here is an easy way to reproduce this behavior:

1. npm install -g @types/sequelize sequelize
2. Replace node_modules/@types/sequelize/index.d.ts with the following

declare namespace sequelize {
    interface Model<T>  {
        doSomething(arg: T): this;
    }
}

declare var sequelize: { Model: sequelize.Model<any> };

export = sequelize;

3. create a file with the following contents:

import { Model } from 'sequelize';

let a: Model<number> = null as any;


a.doSomething(5).doSomething();

Workaround:
Use import * as ... syntax and the names will resolve correctly.

まず、提供されたsequelize宣言を使い、名前付きインポート構文でModelをインポートして問題を再現します。polymorphic thisをチェックする際に、コンパイラーがエクスポートされた変数と同名のinterfaceをどのように解決するかを追跡します。完了条件は、例でModelが推論され、namespace-import workaroundを必要とせずにチェーン呼び出しが許可されることです。