Isolated declarations quick fix defaults to including renamed properties #59547

MichaelMitchell-at · 2024-08-07T08:57:23Z

🔎 Search Terms

isolated declarations quick fix rename ts2842 ts9007

🕗 Version & Regression Information

This is the behavior in every version I tried

⏯ Playground Link

https://www.typescriptlang.org/play/?isolatedDeclarations=true&ts=5.6.0-dev.20240807#code/KYDwDg9gTgLgBAMwK4DsDGMCWEWIBQCUcA3gFBwVxTAxJS5x57ECGAXHAEYC HrHABm4EOANwiYAJnAC8APhLCAhAG5S3IA

💻 Code

export function f() {
    return  (({a: b}: {a: 0}): void => {})!;
}

🙁 Actual behavior

Quick fix introduces a type error:

export function f(): ({ a: b }: { a: 0; }) => void {
//                         ~
//                         'b' is an unused renaming of 'a'. Did you intend to use it as a type annotation? (2842)
    return  (({a: b}: {a: 0}): void => {})!;
}

🙂 Expected behavior

export function f(): ({a}: { a: 0; }) => void {
    return  (({a: b}: {a: 0}): void => {})!;
}

Additional information about the issue

While the quick fix is consistent with the emitted declaration, it ideally wouldn't lead to another type error which can be avoided.
There are cases where it may make sense to preserve the renaming, most obviously

export function f(): ({ a: b }: { a: 0; }) => typeof b {
    return (({a: b}: {a: 0}): typeof b => b)!;
}

but also perhaps

export function f() {
    return  (({a: b}: {a: 0}, a: {}): void => {})!;
}

though, maybe surprisingly, this would currently this still result in ts(2842)

export function f(): ({ a: b }: { a: 0; }, a: {}) => void {
//                         ~
//                         'b' is an unused renaming of 'a'. Did you intend to use it as a type annotation? (2842)
    return  (({a: b}: {a: 0}, a: {}): void => {})!;
}

Perhaps this could be relaxed. While b is unused in the direct sense, it technically has value in that it avoids the naming collision between the as.

The text was updated successfully, but these errors were encountered:

jakebailey · 2024-08-07T16:56:19Z

IIRC we've tried to fix this particular thing multiple times now (at least for declaration emit), and have ended up just reverting all of the code that tries to elide these as the effort was just far too error-fraught.

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Isolated declarations quick fix defaults to including renamed properties #59547

Isolated declarations quick fix defaults to including renamed properties #59547

MichaelMitchell-at commented Aug 7, 2024 •

edited

Loading

jakebailey commented Aug 7, 2024 •

edited

Loading

Isolated declarations quick fix defaults to including renamed properties #59547

Isolated declarations quick fix defaults to including renamed properties #59547

Comments

MichaelMitchell-at commented Aug 7, 2024 • edited Loading

🔎 Search Terms

🕗 Version & Regression Information

⏯ Playground Link

💻 Code

🙁 Actual behavior

🙂 Expected behavior

Additional information about the issue

jakebailey commented Aug 7, 2024 • edited Loading

MichaelMitchell-at commented Aug 7, 2024 •

edited

Loading

jakebailey commented Aug 7, 2024 •

edited

Loading