Module Resolution: allow subpath imports that start with `#/`

[Boshen]

🔍 Search Terms

module resolution package imports

✅ Viability Checklist

• 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 isn't a request to add a new utility type: https://github.com/microsoft/TypeScript/wiki/No-New-Utility-Types
• This feature would agree with the rest of our Design Goals: https://github.com/Microsoft/TypeScript/wiki/TypeScript-Design-Goals

⭐ Suggestion

See nodejs/node#60864

📃 Motivating Example

This allows us to define symmetric exports and imports field in package.json:

{
  "exports": {
    "./*": "./src/*"
  },
  "imports": {
    "#/*": "./src/*"
  }
}

and allows us to migrate away from compilerOptions.paths.

💻 Use Cases

See above

The code requires changing is

TypeScript/src/compiler/moduleNameResolver.ts

Line 2649 in b33d372

if (moduleName === "#" || startsWith(moduleName, "#/")) {