[BUG] In the generated description file, the class type does not check the implemented interface.

[ZSkycat]

TypeScript Version: 3.1.0-dev.20180818

Search Terms: description file class type interface implements

Code

export type LibObjectType = 'Circle' | 'Square';

export interface LibObject {
    readonly type: LibObjectType;
    readonly id: number;
}

export class LibCircle implements LibObject {
    readonly type = 'Circle';
    readonly id: number = Date.now();
}

export class LibSquare implements LibObject {
    readonly type = 'Square';
    readonly id: number = Date.now();
}

Expected behavior:

// index.d.ts
export declare class LibCircle implements LibObject {
    readonly type: 'Circle';
    readonly id: number;
}

Actual behavior:

// index.d.ts
export declare class LibCircle implements LibObject {
    readonly type: string;
    readonly id: number;
}

Playground Link:
https://github.com/ZSkycat/issue-typescript-20180821-1

Related Issues:

[weswigham]

Duplicate of #25990,

Two part fix is already up involving #26556 and #26313

[ZSkycat]

@RyanCavanaugh @weswigham
I found a new issue. The correct type cannot be inferred without using readonly.
Is this an expected behavior?
Should I open a new issue?

export type LibObjectType = 'Circle' | 'Square';

export interface LibObject {
    type: LibObjectType;
    id: number;
}

export class LibCircle implements LibObject {
    type = 'Circle';
    id: number = Date.now();
}

export class LibSquare implements LibObject {
    type = 'Square';
    id: number = Date.now();
}

[weswigham]

That's expected. Mutable locations widen literal types to their base unless appropriately contextually typed, and class properties aren't coming contextualized by their base. We have a bunch of discussions open on that.