JavaScript file: Shadowing require still behaves like the global one

[Derugon]

🔎 Search Terms

require shadowing javascript import scope local

🕗 Version & Regression Information

• This changed between versions 4.0.5 and 4.1.2 (since require module resolution was introduced in 4.1.0-dev.20200818 with Alias for commonjs require in JS #39770).

⏯ Playground Link

https://www.typescriptlang.org/play/?esModuleInterop=false&jsx=0&module=0&filetype=js&q=422#code/GYVwdgxgLglg9mABAUwB4EMC2AHANsxACgEpEBvAKEWsQHoAqexAAW3QCctyBnKdmMAHMAvojBYC9WlRqhIsBInbIAjiBjLC4zMlJklyKCHZIAciEwAjZOy0TSwmdQgJeibnB3mrNxAF4DNQ1kQgByDy8JUOIAbgphIA

💻 Code

function () {
    /** @param {string} name */
    function require(name) { return Number(name) }

    const someNumber = require('someName');
}

🙁 Actual behavior

1. someNumber is an import.
2. It raises a type import error:

Cannot find module 'someName' or its corresponding type declarations.

🙂 Expected behavior

1. someNumber has type number.
2. No error is raised.

Additional information about the issue

This is only the case when using type inference with JavaScript files. With TypeScript it works as expected (playground):

function () {
    function require(name: string) { return Number(name) }

    const someNumber = require('someName');
}

If the type of someNumber is explicitely written, it also works as expected (playground):

function () {
    /** @param {string} name */
    function require(name) { return Number(name) }

    /** @type {number} */
    const someNumber = require('someName');
}

[RyanCavanaugh]

There are too many other cases where require appears shadowed but actually isn't (e.g. AMD module bodies). For consistency, require is always inferred to be the module-importing function.