[ID] `--isolatedDeclarations` disallows `const` initialized with a regex literal

🔍 Search Terms

• isolatedDeclarations
• isolated declaration

✅ 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

I an unsure if it is a bug or a feature request...

An exported const without type annotation and initialized with a regex literal triggers the following error error TS9010: Variable must have an explicit type annotation with --isolatedDeclarations. in isolated declaration mode.

If I understand correctly, isolated declaration should allow unannotated const initialized with any literal?

📃 Motivating Example

See an example on the playground.

💻 Use Cases

This could avoid a trivial type annotation.

Reproduce the linked Playground example with --isolatedDeclarations and confirm the TS9010 diagnostic for an exported const initialized by a regex literal. Trace the compiler's isolated-declaration validation and add a regression test showing the literal is accepted without a redundant annotation.