Import types in d.ts files contain relative paths to node_modules

[jwbay]

TypeScript Version: 3.0.0-dev.20180601

Search Terms: declaration import types

Code
src/one/two/export.ts:

import * as CSS from 'csstype';
export const use = (f: CSS.Properties['fontWeight']) => f;

src/one/two/consumer.ts:

import { use } from "./export";
export const asdf = use ;

Expected behavior:
consumer.d.ts has something like

export declare const asdf: (f: import("csstype/index").FontWeightProperty) => import("csstype/index").FontWeightProperty;

Actual behavior:
It has relative paths to node_modules, based on the source file's location at compile time. This places an assumption on the location of the d.ts file when it's consumed externally.

export declare const asdf: (f: import("../../../node_modules/csstype/index").FontWeightProperty) => import("../../../node_modules/csstype/index").FontWeightProperty;

Playground Link: N/A

Related Issues: #24556, but csstype does specify a types key in package.json

[weswigham]

Small repro:

// @declaration: true
// @filename: node_modules/foo/index.d.ts
export interface SomeProps {
 x: number;
}

export function foo(): SomeProps;
// @filename: entry.ts
import { foo } from "foo";
export const x = foo();

emits

export declare const x: import("./node_modules/foo/index").SomeProps;

you'd much rather it use the node module resolution style "foo" than "./node_modules/foo/index" 😛

There is a wrench, though:

// @declaration: true
// @filename: node_modules/foo/other/index.d.ts
export interface OtherIndexProps {}
// @filename: node_modules/foo/other.d.ts
export interface OtherProps {}
// @filename: node_modules/foo/index.d.ts
import { OtherProps } from "./other";
import { OtherIndexProps } from "./other/index";

export function foo(): [OtherProps, OtherIndexProps];
// @filename: entry.ts
import { foo } from "foo";
export const x = foo();

in this case, writing import("foo/other"), by nodejs rules, always yields the loose file. So you need to know that you can't just write import("foo/other") to refer to import("foo/other/index"), since the loose file overrides it. All this means that to do this right, you pretty much need to check the full fs to ensure you don't shorten to something that refers to something else.

Minimally, stripping off the leading relative dir parts and node_modules part is safe, reduces verbosity, and improves portability, though.

[zsgalusz]

I can reproduce this issue in 2.9.1, it's a major blocker for us in upgrading to TS2.9.

[esamattis]

TypeScript 2.9.2 made some changes to this but it's still broken.

2.9.1 generated type import paths like ./node_modules/redux/index but now in 2.9.2 they are ../../../../../Users/esamatti/code/mylibrary/node_modules/redux

In my case just redux would be the desired output.