tsc 2.9.x generating incorrect type definitions for import types #25278

tldr; when using the new import types feature of tsc 2.9, there are certain circumstances where the import( part is missing.

Version: 3.0.0-dev.20180626

Code

See https://github.com/jrf0110/tsc-declaration-bug/blob/master/workspaces/button-consumer/dist/index.d.ts#L2 for a full example

import { MyButton } from "@cloudflare/button-thing";
export const Something = MyButton;

Expected behavior:

/// <reference path="../../../types/component-button.d.ts" />
export declare const Something: typeof import('@cloudflare/component-button').Button;

Actual behavior:

/// <reference path="../../../types/component-button.d.ts" />
export declare const Something: typeof '@cloudflare/component-button'.Button;

Playground Link: https://github.com/jrf0110/tsc-declaration-bug

Additional Info

We saw this come up using yarn workspaces. I'm not exactly sure if using yarn workspaces is required to reproduce. Nonetheless, this definitely seems like a bug with tsc itself.

I suspect this has something to do with importing from .d.ts files that declare a module, as is the case in the linked example.