Hoisted vars in blocks at module scope generate in invalid d.ts files when referenced using typeof

[lucacasonato]

🔎 Search Terms

• hoisting
• var declaration
• declaration files
• typeof
• module

🕗 Version & Regression Information

This changed between versions 5.5.0-beta and 5.5.0-dev.20240517

⏯ Playground Link

https://www.typescriptlang.org/play/?ts=5.5.0-dev.20240517#code/N4KABBYG4IYE5hmAvGARGg3CAviApgB4AOA9nAC5gA2+VARgFxgUCex+pAZotkA

💻 Code

{
    var a = "";
}
export let b: typeof a;

🙁 Actual behavior

export declare let b: typeof a;

🙂 Expected behavior

d.ts emit of either:

var a: string;
export declare let b: typeof a;

or

export declare let b: string;

Probably it should do the first, then it would be compatible with isolated declarations.

Additional information about the issue

No response

[lucacasonato]

@weswigham This is not isolated declarations specific. This is a bug introduced between 5.5.0-beta and 5.5.0-dev.20240517. This reproduction is not related to isolated declaration at all. This code fails to emit correctly / does not raise a diagnostic in the latest dev build, but it does work in 5.5.0-beta.