Importing types from a js module doesn't work

[zombie]

TypeScript Version: 3.2.0-rc

Code

Example from TypeScript 2.9 release notes:

// module.js

class Pet {
  get name() {
    return "";
  }
}

module.exports = {Pet};

// global-script.ts

// error TS2694: Namespace `"module".export=` has no exported member `Pet`.

function adopt(p: import("./module").Pet) {
  console.log(`Adopting ${p.name}...`);
}

// This works, though it's far from ideal, and not always applicable.

let module: typeof import("./module");

function adopt2(p: typeof module.Pet.prototype) {
  console.log(`Adopting ${p.name}...`);
}

// a.js

// error TS2694: Namespace `"module".export=` has no exported member `Pet`.

/**
 * @param {import("./module").Pet} p
 */
function walk(p) {
  console.log(`Walking ${p.name}...`);
}

// Works, showing that type information is exported/preserved on some level.

/**
 * @typedef {import("./module")} module
 * @param {typeof module.Pet.prototype} p
 */
function walk2(p) {
  console.log(`Walking ${p.name}...`);
}

Typecheck using:

tsc -t es2017 --checkjs --allowjs --noemit a.js global-script.ts

Expected behavior:
Type annotation should work and not error out.

Actual behavior:
error TS2694: Namespace "module".export= has no exported member Pet.

Related Issues:
Issue #23936 seems possibly related, but not sure.

[weswigham]

I'm not sure if we recognize

module.exports = {Pet};

As exporting an alias of Pet yet.

[dgoldstein0]

This doesn't look like a commonjs vs es6 issue to me.

Here's an alternative repro:

import * as x from "tslib";

const assign: import("tslib").__assign = x.__assign; // Namespace '"tslib"' has no exported member '__assign'.(2694)
let module: typeof import("tslib");

const assign2: typeof module.__assign = x.__assign; // works

https://www.typescriptlang.org/play?#code/JYWwDg9gTgLgBAKjgQwM5wB5wGZQiOAIhlQBtgAjQgbgFgAoBgYwgDtV41VgBzVgLjihIsABTEylQgEoAdAH15XXqzgBeTAqWpufOo3qkApvBAQAJgFdjgmAE8wRiNiHhoMcSXJVp+5mw4UHRUAJlsHJxczK2MtZT51TUV41n0gA

this seems to be a general issue with import() in the type position, when the target of the import is not a typescript file

[dgoldstein0]

since the issue I posted isn't really a JS issue (as this one is tagged) I opened a separate issue for it. I suppose you can dedupe if you think it's the same issue.