resolving library types with import assignment `import = require()` fails

[ayZagen]

Steps to reproduce

Trying to use @sendgrid/mail package which has following type definitions:

// @sendgrid/mail/src/mail
declare class MailService {}

declare const mail: MailService;
// @ts-ignore
export = mail;

export {MailService};
export {MailDataRequired};
export {ClientResponse};
export {ResponseError};

// index.d.ts
import MailService = require("@sendgrid/mail/src/mail");

export = MailService;

https://github.com/sendgrid/sendgrid-nodejs/blob/main/packages/mail/index.d.ts

Behavior with typescript@6.0

It works ok.

Behavior with tsgo

Following errors occur.

error TS2305: Module '"@sendgrid/mail"' has no exported member 'MailDataRequired'.

import type { MailDataRequired } from "@sendgrid/mail"
                ~~~~~~~~~~~~~~~~

error TS2595: 'MailService' can only be imported by using a default import.

import { MailService } from "@sendgrid/mail"
           ~~~~~~~~~~~

[jakebailey]

Without actually investigating it, I don't know how much we can even trust that this code works if they're quite literally // @ts-ignore-ing an error and illegally mixing export = with export {}. You should not be able to do both.

[ayZagen]

Yeah, I totally understand. They probably tried it this way (I have no idea why), saw that it worked, and then never touched it again.

I mainly wanted to contribute to tsgo, since this was the only error I encountered that behaved differently compared to tsc.