microsoft / microsoft/TypeScript

jsdoc in JS: arguments object does not infer types from the containing function

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Description

🔎 Search Terms

argument object infer

🕗 Version & Regression Information

I see it in next but I'm sure it's the way it's always behaved.

⏯ Playground Link

https://tsplay.dev/WyQbbW

💻 Code
/** @type {(obj: Record<PropertyKey, unknown>, property: PropertyKey, value: unknown, nonEnumerable?: boolean | null, nonWritable?: boolean | null, nonConfigurable?: boolean | null, loose?: boolean) => void} */
module.exports = function defineDataProperty(
	obj,
	property,
	value
) {
	if (!obj || (typeof obj !== 'object' && typeof obj !== 'function')) {
		throw new TypeError('`obj` must be an object or a function`');
	}
	if (typeof property !== 'string' && typeof property !== 'symbol') {
		throw new TypeError('`property` must be a string or a symbol`');
	}
	if (arguments.length > 3 && typeof arguments[3] !== 'boolean' && arguments[3] !== null) {
		throw new TypeError('`nonEnumerable`, if provided, must be a boolean or null');
	}
	if (arguments.length > 4 && typeof arguments[4] !== 'boolean' && arguments[4] !== null) {
		throw new TypeError('`nonWritable`, if provided, must be a boolean or null');
	}
	if (arguments.length > 5 && typeof arguments[5] !== 'boolean' && arguments[5] !== null) {
		throw new TypeError('`nonConfigurable`, if provided, must be a boolean or null');
	}
	if (arguments.length > 6 && typeof arguments[6] !== 'boolean') {
		throw new TypeError('`loose`, if provided, must be a boolean');
	}

	var nonEnumerable = arguments.length > 3 ? arguments[3] : null;
	var nonWritable = arguments.length > 4 ? arguments[4] : null;
	var nonConfigurable = arguments.length > 5 ? arguments[5] : null;
	var loose = arguments.length > 6 ? arguments[6] : false;
};
🙂 Expected behavior

arguments[3] (and 4, 5, and 6) should all have a type as defined in the function's type (in this case, boolean | null for the first three, and boolean for the fourth).

This should result in nonEnumerable, nonWritable, and nonConfigurable being of type boolean | null, and loose being of type boolean.

🙁 Actual behavior

Those four variables have a type of any.

Additional information about the issue

This is using jsdoc in a .js file with allowJs/checkJs enabled.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the linked TypeScript playground and reproduce the inferred types for arguments[3] through arguments[6] in the shown JavaScript example. Trace the checker’s handling of JSDoc function types and the arguments object, then add a regression test. Done means those indexed arguments infer boolean | null or boolean as specified instead of any.

Written by the indexing model from the issue text.

Assessment

Tech stack
javascript, typescript
Domain
compilers
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
38/100

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