Declaration file references global augmenting package

[AviVahl]

This issue came up as part of a real component library breaking for its consumers, demanding @emotion/core.

I was able to get a much smaller reproduction ready to show the behaviour.

TypeScript Version: 3.7.2 & 3.8.0-dev.20191125

Search Terms:
triple slash reference declaration

Steps to reproduce
clone https://github.com/AviVahl/ts-declaration-reference
yarn
yarn build

Expected behavior:
dist/inferred-comp-export.d.ts should not contain a reference to @emotion/core..

Actual behavior:
dist/inferred-comp-export.d.ts contains: /// <reference types="@emotion/core" />

Playground Link:
Cannot reproduce in playground. It has to do with declaration emit and third party augmenting package.

Related Issues:
#34749
#11849

Observations:

• @emotion/core/types/index.d.ts contains:

declare module 'react' {
  interface DOMAttributes<T> {
    css?: InterpolationWithTheme<any>
  }
}

commenting it out removes the triple slash from emit.

• commenting out export * from '@emotion/core'; from src/some-other-file.ts gets rid of the triple slash reference.
• In our more-complex real case, we import @storybook/react, which imports @storybook/theming, which re-exports @emotion/core.

[weswigham]

Yeah, I'm going to file this as a bug - given

// @declaration: true
// @filename: node_modules/foo/index.d.ts
export = React;
declare namespace React {
    export interface Component<P={}> { }
}
// @filename: node_modules/bar/index.d.ts
import { Component } from 'foo';
declare module "foo" {
    export interface Component<P> {
        css?: P;
    }
}
// @filename: reexport.ts
export * from "bar";
// @filename: get.ts
import { Component } from 'foo';
export function getComp(): Component {
    return {} as any as Component;
}
// @filename: use.ts
import { getComp } from "./get";

export const obj = {
    comp: getComp()
};

we produce

/// <reference types="bar" />
export declare const obj: {
    comp: import("foo").Component<{}>;
};

for use.ts, while if foo/index.d.ts is just

export interface Component<P={}> { }

we produce

export declare const obj: {
    comp: import("foo").Component<{}>;
};

Clearly we don't always think the triple slash reference is needed, and at somepoint we're confusing an export-assigned-namespace with a referenced-augmentation or something.