static fields should be installed on the decorated class

[JLHwung]

🔎 Search Terms

decorator class static field

🕗 Version & Regression Information

• This is a crash
• This changed between versions ______ and _______
• This changed in commit or PR _______
• This is the behavior in every version I tried (after ES decorators are implemented), and I reviewed the FAQ for entries about decorators
• I was unable to test this on prior versions because _______

⏯ Playground Link

https://www.typescriptlang.org/play?useDefineForClassFields=true&target=9&ts=5.4.0-dev.20240130#code/DYUwLgBA8gTglgczgOwIbAGIHssG4BQ+AxsKgM5kQBCqMEA3gL6EBmArskWHFshACYgiACmxYAlA3wRo8JGkw4IAXghiCMmODYw+NGAWb4AAoKLFSFNUvrSIZMKm5EIABw33HziKiJEQFFh0qB4OTnAuALbCkkz4RkS8ZFigAHTAWAjC+qkAFuRQAO7IAAowWK4gMGAAnsIARK714gA01LR5BcVlFVW1DajNbTn5ZEWl5ZXVdfWRzeIEicjJaRlZsIgo6GKdY92TfTNNrbKbCjuj4z1T-fWDJxvy2zi7VwfTDXPiC0A

💻 Code

let OriginalFoo;

class Bar {}

function dec(Foo) {
  OriginalFoo = Foo;
  return Bar;
}

@dec
class Foo {
  static p;
  static accessor a;
  static m() {}
}

console.log(Bar.hasOwnProperty("p"), Bar.hasOwnProperty("a"), Bar.hasOwnProperty("m"));
console.log(OriginalFoo.hasOwnProperty("p"), OriginalFoo.hasOwnProperty("a"), OriginalFoo.hasOwnProperty("m"));

🙁 Actual behavior

It prints

false,  false,  false 
true,  true,  true 

🙂 Expected behavior

It should print

true, true, false
false, false, true

Additional information about the issue

Per RS: ClassDefinitionEvaluation:
In step 27 the static methods are installed to the original class OriginalFoo.
In step 37 the receiver F is assigned by the decorated class Bar.
In step 40 the static fields and accessors are initialized on the decorated class Bar.
So OriginalFoo should contain all the static methods while Bar should contain all the static fields and accessors.

[JLHwung]

I checked the spec again and IIRC the static accessors should be installed on OriginalFoo, however, its backing storage private field should be installed on Bar, so accessing OriginalFoo.a should throw an error as the storage key is not defined on OriginalFoo, but OriginalFoo.hasOwnProperty("a") should return true anyway.

[rbuckton]

It should print

true, true, false
false, false, true

Per the spec (and as is reflected in your other comment), it should actually print

true, false, false
false, true, true

accessing OriginalFoo.a should throw an error as the storage key is not defined on OriginalFoo

Yes, we currently emit __classPrivateFieldGet(_classThis, _classThis, "f", _Foo_a_accessor_storage) for the accessor when we should emit __classPrivateFieldGet(this, _classThis, "f", _Foo_a_accessor_storage) instead.

[JLHwung]

Per the spec (and as is reflected in your other comment), it should actually print

true, false, false
false, true, true

@rbuckton Yes you are right, back then I confused the backing storage key definition with the accessor definition.