Broken emit with private field in class decorator

[Jamesernator]

Bug Report

🔎 Search Terms

private field, decorators, broken emit

🕗 Version & Regression Information

• This is the behavior in every version I tried, and I reviewed the FAQ for entries about decorators

⏯ Playground Link

Playground link with relevant code

💻 Code

function makeDecorator(fn: (...args: any[]) => any) {
    return function decorateClass<C extends new (...args: any[]) => any>(
        klass: C, 
        ctx: ClassDecoratorContext,
    )  {
        // The implementation of this doesn't matter
    }
}

@makeDecorator(x => x.#foo)
class Foo {
    #foo: number = 3;
}

🙁 Actual behavior

The generated code is syntatically incorrect with the error:

Unexpected token ')' 

This happens on the line, basically nothing is emitted after the x.:

    let _classDecorators = [makeDecorator(x => x.)];

🙂 Expected behavior

Functioning code should be emitted.

[fatcerberus]

I'm pretty sure there's no legal emit for this code. Private fields aren't accessible outside the class body (it's a syntax error), which I don't think the decorator is part of.

[so1ve]

x => x.#foo is invalid

[Jamesernator]

Private fields aren't accessible outside the class body (it's a syntax error), which I don't think the decorator is part of.

If it's meant to be syntax error that is fine, my assumption was that given TS parsed it correctly decorators must still be in class scope. Obviously TS should report this as a syntax error if that is the case for the decorators spec.

[RyanCavanaugh]

Yeah, just to be clear, the bug here is that we're not issuing an error