typesVersions should support aliasing specific files (or document this will not be supported)

Suggestion

🔍 Search Terms

typesVersions, backwards compatibility, path alias

✅ Viability Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, new syntax sugar for JS, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

⭐ Suggestion

Enable aliasing a single file with Advanced Types or document this isn't possible. The language on the docs currently says:

File redirects

When you want to only change the resolution for a single file at a time, you can tell TypeScript the file to resolve differently by passing in the exact filenames:

However, passing any exact filename doesn't seem to work. For example, if dist/index.d.ts imports dist/helpers/advanced-types.d.ts, which should fall back to helpers/legacy-types.d.ts for older TS versions, this doesn't seem to work. I've tried:

• dist/helpers/advanced-types.d.ts
• dist/helpers/advanced-types
• helpers/advanced-types.d.ts
• helpers/advanced-types
• */advanced-types.d.ts
• */advanced-types
• advanced-types.d.ts
• advanced-types

📃 Motivating Example

Using something like template literals, I would like to create a single file that contains these, with some fallbacks with legacy code for TypeScript users who do not have the ability to update right away.

💻 Use Cases

The only workaround I've found is to create another package which exports a different index.d.ts to be used with the main project. There would be too many different uses of the types exported to re-create the entire project with the different imports.