Incorrect ts.transpileModule() emit when imported type shadows type but not constructor of global symbol

[frigus02]

🔎 Search Terms

transpileModule, isolatedModules

🕗 Version & Regression Information

• This is the behavior in every version I tried: v5.2.2, v5.3.2, v5.4.0-dev.20231123

⏯ Playground Link

Bug Workbench

💻 Code

// @isolatedModules

import {Date} from "./types";

function foo(a: Date) {
 const b = new Date(a.year, a.month, a.day);
 return b.getTime();
}

// @filename: types.d.ts
export interface Date {
 day: number;
 month: number;
 year: number;
}

🙁 Actual behavior

Regular emit:

function foo(a) {
 const b = new Date(a.year, a.month, a.day);
 return b.getTime();
}

ts.transpileModule() emit:

import {Date} from "./types";
function foo(a) {
 const b = new Date(a.year, a.month, a.day);
 return b.getTime();
}

The ts.transpileModule() emit has a runtime error because the imported Date either doesn't exist or doesn't have a constructor.

🙂 Expected behavior

Same (or at least runtime equivalent) emit of transpileModule.

Additional information about the issue

I realize this code is probably not ideal. I was honestly surprised that this type-checks. I'm happy with any solution here:

• Make this code an error in all configurations.
• Make isolatedModules require import type.
• ...

[frigus02]

I've been using frigus02@cfe3335 to find and fix issues in our code base. If this comes close to an acceptable fix, I'd be happy to clean up and open a PR.