Unexpected "'Type' is declared but its value is never read." error with jsdoc @import syntax

[DavidBruant]

🔎 Search Terms

jsdoc @import "is declared but its value is never read"

🕗 Version & Regression Information

I have seen this error since the introduction of @import in jsdoc comments (TS 5.5 if i recall correctly)

⏯ Playground Link

No response

💻 Code

I made a testcase repo https://github.com/DavidBruant/jsdoc-import-unused-testcase
It is as reduced as a managed to make it

The code :

/** @import {ImportedType} from './types.d.ts' */

function id() { return undefined }

/** @type {Set<ImportedType>} */
export const phases = new Set(['a', 'b'])

The types.d.ts file:

export type ImportedType = 'a' | 'b'

🙁 Actual behavior

tsc and VSCodium both say:

code.js:1:5 - error TS6133: 'ImportedType' is declared but its value is never read.

1 /** @import {ImportedType} from './types.d.ts' */

🙂 Expected behavior

There shouldn't be an error because of the line using the type : /** @type {Set<ImportedType>} */

We've had this error in plently of places. It also seems like it occurs more regulary when the type is used within a generics

Additional information about the issue

For some reason, removing function id() { return undefined } from the code solves the problem while it seems completely unrelated to the problem

[Andarist]

Interestingly, I can't repro it using the bug workbench: workbench

[regseb]

I think I have the same problem.

• TypeScript reports that an import is useless when used in the return type of a function. bad.js 👎
• But it doesn't report a problem if it's used in the return type of two functions. good1.js 👍
• Or if used in the type of a variable good2.js 👍

---

• package.json

  {
    "name": "testcase",
    "version": "1.0.0",
    "type": "module",
    "dependencies": {
      "@types/node": "22.10.5",
      "playwright": "1.49.1",
      "typescript": "5.7.3"
    }
  }

• tsconfig.json

  {
    "compilerOptions": {
      "module": "nodenext",
      "noUnusedLocals": true,
      "noEmit": true,
      "checkJs": true
    }
  }

• bad.js

  /**
   * @import { Page } from "playwright"
   */
  
  /**
   * @returns {Page|undefined}
   */
  function foo() {
      return undefined;
  }
  
  console.log(foo());

• good1.js

  /**
   * @import { Page } from "playwright"
   */
  
  /**
   * @returns {Page|undefined}
   */
  function foo() {
      return undefined;
  }
  
  /**
   * @returns {Page|undefined}
   */
  function bar() {
      return undefined;
  }
  
  console.log(foo(), bar());

• good2.js

  /**
   * @import { Page } from "playwright"
   */
  
  /**
   * @type {Page|undefined}
   */
  let foo;
  
  console.log(foo);

1. npm install
2. npx tsc

   bad.js:2:4 - error TS6133: 'Page' is declared but its value is never read.
   
   2  * @import { Page } from "playwright"
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   
   
   Found 1 error in bad.js:2