Declaration emit reveals paths within dependency that were not referred to in the source file

Context:

• Generating declaration files

Declaration emit reveals paths within dependency that were not referred to in the source file:

export declare const instance: import("dependency/internal-types").TheInterface;

This is a problem because changing paths within a dependency can break a dependent package.

TypeScript Version: 3.9.0-dev.20200212

Search Terms:

• inline import declaration
• declaration external relative path

Code

node_modules/@types/dependency/entrypoint.d.ts

import { TheInterface } from "./internal-types";
export { TheInterface };
export declare function getInstance(): TheInterface;

node_modules/@types/dependency/internal-types.d.ts

export interface TheInterface {}

node_modules/@types/dependency/index.d.ts

// empty - doesn't matter for this example

example.ts

import { getInstance } from "dependency/entrypoint";
export const instance = getInstance();

src/app/tsconfig.json

{
    "compilerOptions": {
        "declaration": true,
    }
}

Expected behavior:

example.d.ts

export declare const instance: import("dependency/entrypoint").TheInterface;

Actual behavior:

example.d.ts

export declare const instance: import("dependency/internal-types").TheInterface;

It seems that part of the solution could involve having the compiler avoid using relative paths in types (import("<relativepath>").<typename>) if the relativepath is outside the project.

Repro Repo: https://github.com/mheiber/repro-rel-import-inlining

Related Issues:

• Declaration emit should not inline type definitions - #37151
• Proposal: Bundling TS module type definitions - #4433

Issue written with the help of: @rricard, @robpalme and @mkubilayk