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Using `satisfies` on a self-referencing object causes `any` - TS 4.9.2-RC

See original GitHub issue

Bug Report

šŸ”Ž Search Terms

šŸ•— Version & Regression Information

Version 4.9.2-rc

šŸ’» Code

interface Items {
  id: 'a' | 'b';
  condition: () => boolean;
}

// 'items' implicitly has type 'any' because it does not have a type annotation and is referenced directly or indirectly in its own initializer.ts (7022)
const items = {
  foo: {
    id: 'a',
    condition: () => true
  },
  bar: {
    id: 'b',
    condition: () => items.foo.id === 'a'
  },
} satisfies Record<string, Items>;

šŸ™ Actual behavior

items implicitly has type any.

šŸ™‚ Expected behavior

items should be checked with the Items interface and still have typesafe keys.

Issue Analytics

  • State:open
  • Created 10 months ago
  • Comments:5 (3 by maintainers)

github_iconTop GitHub Comments

2reactions
fatcerberuscommented, Nov 12, 2022

I feel like TS needs better error messages.

The error textā€¦

because it does not have a type annotation and is referenced directly or indirectly in its own initializer

ā€¦implies that simply referencing yourself is sufficient cause for error, but in reality sometimes itā€™s allowed (intentionally, even). Iā€™m starting to see why people complain so much about TS being inconsistentā€”context matters, but the error messages tend to speak in absolutes, making any difference in error-producing behavior look like a bugā€¦

I guess if I had to put my finger on it, itā€™s the difference between ā€œyouā€™re not allowed to do thisā€ vs. ā€œI canā€™t resolve this and hereā€™s the complication I ran into while tryingā€, and itā€™s easy to read some errors as implying the former when itā€™s really the latter.

1reaction
DanielRosenwassercommented, Nov 12, 2022

Iā€™m not sure if thereā€™s a way for us to avoid pulling on the type of types here before itā€™s been initialized, but since you can observe the same thing with a ā€œfakeā€ version of satisfies in older versions of TypeScript, I might be tempted to say that this is an expected design limitation.

interface Items {
  id: 'a' | 'b';
  condition: () => boolean;
}

declare function satisfies<U, T extends U = U>(val: T): T

// 'items' implicitly has type 'any' because it does not have a type annotation and is referenced directly or indirectly in its own initializer.ts (7022)
const items = satisfies<Record<string, Items>>({
  foo: {
    id: 'a',
    condition: () => true
  },
  bar: {
    id: 'b',
    condition: () => items.foo.id === 'a'
  },
});

That said, maybe we could do something a little different here. We could possibly defer all comparisons for satisifes until after all deferred function bodies have been checked as well. So basically satisfies does nothing except for provide a contextual type at first, and then is checked after everything else.

Read more comments on GitHub >

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