"unique symbol" is generated to multiple .d.ts files #40786

zoltan-mihalyi · 2020-09-26T09:40:30Z

TypeScript Version: 4.0.3
Search Terms:
unique symbol, declaration, .d.ts, invalid, TS4023

Code

a.ts

type AX = { readonly A: unique symbol };
export const A: AX = 0 as any;

b.ts

import { A } from './a';
export const A1 = A;

tsconfig.json

{
  "compilerOptions": {
    "declaration": true,
    "strict": true,
    "noImplicitAny": true,
    "rootDir": "src",
    "outDir": "lib"
  }
}

Expected behavior:
Typescript should either throw TS4023, or generate the following code for b.d.ts:

import { A } from './a';
export declare const A1: typeof A;

Actual behavior:
Typescript generates "unique symbol" to both a.d.ts and b.d.ts:

a.d.ts

declare type AX = {
    readonly A: unique symbol;
};
export declare const A: AX;
export {};

b.d.ts

export declare const A1: {
    readonly A: unique symbol;
};

Project Link:
project.zip

weswigham · 2020-10-01T22:05:27Z

Hm. I suppose we should issue an error here? The local type from a isn't reachable in b, so we print the type anonymously; however it contains a unique symbol which, by rights, refers to a symbol in a different file; so we can't really serialize it. The only thing you could write out is something like export declare const A1: typeof A, like you propose, but our declaration emit generally doesn't write out typeof queries on its own (simply because it doesn't generalize - it'd only work for exactly declarations of the form var x = some.dotted.name, which is an odd syntactic carve-out to make for TS code), which is why it's more in-line with our normal behavior to report an error on the attempted usage of a private symbol, and require an annotation.

weswigham · 2020-10-01T22:24:48Z

In fact, the error already exists, and is simply failing to trigger due to an unfortunate bug.

RyanCavanaugh added the Needs Investigation This issue needs a team member to investigate its status. label Sep 29, 2020

RyanCavanaugh assigned weswigham Sep 29, 2020

RyanCavanaugh added this to the TypeScript 4.2.0 milestone Sep 29, 2020

weswigham mentioned this issue Oct 1, 2020

Limit when we allow nested unique symbols to be serialized #40886

Merged

typescript-bot added the Fix Available A PR has been opened for this issue label Oct 1, 2020

weswigham added Bug A bug in TypeScript Domain: Declaration Emit The issue relates to the emission of d.ts files and removed Fix Available A PR has been opened for this issue Needs Investigation This issue needs a team member to investigate its status. labels Oct 1, 2020

typescript-bot added the Fix Available A PR has been opened for this issue label Oct 1, 2020

weswigham closed this as completed in #40886 Oct 5, 2020

sandersn mentioned this issue May 19, 2021

Add Intl.DisplayNames types #44022

Closed

4 tasks

"unique symbol" is generated to multiple .d.ts files #40786

"unique symbol" is generated to multiple .d.ts files #40786

zoltan-mihalyi commented Sep 26, 2020 •

edited

weswigham commented Oct 1, 2020

weswigham commented Oct 1, 2020

"unique symbol" is generated to multiple .d.ts files #40786

"unique symbol" is generated to multiple .d.ts files #40786

Comments

zoltan-mihalyi commented Sep 26, 2020 • edited

weswigham commented Oct 1, 2020

weswigham commented Oct 1, 2020

zoltan-mihalyi commented Sep 26, 2020 •

edited