Using decorators on class reports class is declared but never used

Bug Report

🔎 Search Terms

“decorator unused” “decorator declared but never used”

🕗 Version & Regression Information

• I was unable to test this on prior versions because my project relies on auto-accessor which is only available since ts 4.9

⏯ Playground Link

Playground link with relevant code

💻 Code

function defineElement(name: string): any {
}

@defineElement("my-element")
class MyElement extends HTMLElement {

}

🙁 Actual behavior

TypeScript reports 'MyElement' is declared but never used..

And If I click “Quick Fix” in vscode, it removes my entire class declaration and decorator call.

🙂 Expected behavior

No error reports.

[fatcerberus]

It’s admittedly kind of a gray area, the class is only “used” in the same sense that let x = 0; x++; “uses” x. Having decorators with non-local (to the class) side effects feels like an anti-pattern. You don’t “decorate” a Christmas tree by adding more furniture to the room around it…

[MartinJohns]

I think it would be much better to either ignore the error, export the class or use it in an empty dummy function than to make this not an error. I believe in the majority of cases this legitimately considered unused.