microsoft / microsoft/TypeScript

JSDoc disappeared in overloading with mapped type

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Bug Domain: JSDoc
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Description

Bug Report

🔎 Search Terms

vscode, jsdoc

🕗 Version & Regression Information

4.1.3

⏯ Playground Link

example 1, bug, no jsdoc:
No JSDoc if overloading in mapped type
image

example 2, works well:
Has JSDoc if no overloading in mapped type
image

example 3, bug, no jsdoc:
JSDoc disappeared without overloading

JSDoc disappeared without overloading

💻 Code
type ApiDict = {
  /**
   * jsdoc for getString
   */
  getString: string;
  /**
   * jsdoc for getBoolean
   */
  getBoolean: boolean;
};

type Api = {
  [key in keyof ApiDict]: {
    (url: string): ApiDict[key];
    (url: string, config: {}): { data: ApiDict[key]; extra: any };
  };
};

declare const api: Api;

api.getBoolean('', {});
type ApiDict = {
  /**
   * jsdoc for getString
   */
  getString: string;
  /**
   * jsdoc for getBoolean
   */
  getBoolean: boolean;
};

type Api = {
  [key in keyof ApiDict]: {
    (url: string, config: {}): { data: ApiDict[key]; extra: any };
  };
};

declare const api: Api;

api.getBoolean('', {});
/**
 * jsdoc for JsdocDisappearedWithoutOverloading
 */
interface JsdocDisappearedWithoutOverloading {
  (url: string): any;
}

declare const jsdocDisappearedWithoutOverloading: JsdocDisappearedWithoutOverloading;

jsdocDisappearedWithoutOverloading('');
🙂 Expected behavior

All of examples has jsdoc

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 by running the three linked TypeScript Playground examples, comparing the mapped-type overload cases with the working case and the standalone callable interface. Use the provided TypeScript snippets to reproduce the missing JSDoc. Done means all examples retain their declared JSDoc, including mapped types with overloaded call signatures.

Written by the indexing model from the issue text.

Assessment

Tech stack
typescript
Domain
compilers
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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