Better error message when a module declaration is not found, but a module augmentation is?

🔎 Search Terms

declaration, augmentation

🕗 Version & Regression Information

• This is the behavior in every version I tried, and I reviewed the FAQ for entries about module augmentation and declaration files

⏯ Playground Link

Can't be shown on Playground, since it requires two files

💻 Code

// declaration.d.ts

import { ComponentType } from "react";

declare module "a/b" {
    const B: ComponentType<any>;
    // const B: import("react").ComponentType<any>;
    export default B;
}

// file.ts
import B from "a/b";

🙁 Actual behavior

The error message is "Cannot find module 'a/b' or its corresponding type declarations (2307)". I know this works as indended from https://github.com/microsoft/TypeScript/issues/49043#issuecomment-1124047244, so my proposal is only about changing the error message.

🙂 Expected behavior

In the case where TypeScript can't find a declaration of a module but can find its augmentation, it seems very likely the user intended to make it a declaration, but didn't know top-level import/export change the meaning (like I didn't yesterday). It would be nice to have the message tell the user about the problem and guide to fixing it.

Reproduisez le comportement avec les deux fichiers présentés, declaration.d.ts et file.ts, et comparez le diagnostic lorsque la déclaration de module est absente mais que son augmentation est trouvée. Suivez le chemin du diagnostic de résolution de module et mettez à jour le message pour expliquer la distinction entre import/export au niveau supérieur ; vérifiez les indications révisées à l’aide de cet exemple et des tests de diagnostic associés.