Spurious [?] circularity error in getter with spread

[RyanCavanaugh]

Bug Report

🔎 Search Terms

circularity getter

🕗 Version & Regression Information

• This is the behavior in every version I tried

⏯ Playground Link

Playground link with relevant code

💻 Code

type Box = {
 content?: Foo | Box
};
declare const b: Box;
class Foo {
 get foo() {
 return {
 content: this as Foo | Box,
 ...b
 };
 }
}

🙁 Actual behavior

Circularity error on 'foo' when this is probably deferrable

🙂 Expected behavior

No circularity error

Ref. #46981

[Andarist]

The problem comes from within the checkAccessorDeclaration and the getTypeOfAccessors call in it.

This starts a type resolution that ends up with a cycle because getSpreadType tries to create a union of the left type and the right type here. The problem is that this is a subject of subtype union reduction and this find(getPropertiesOfType(source), p => isUnitType(getTypeOfSymbol(p))) leads to requesting the get foo's type while we are still resolving it.

Probably there is a way to defer this but it's not that easy at the moment. Usually, unannotated getters should participate in this find.

[RyanCavanaugh]

Not an error anymore

[Andarist]

Bisected to f218a56...1df5717 and confirmed that it was fixed by #53413

[jakebailey]

Oh what, that PR should have only been a perf optimization, not a behavior change...