Quick info displays incorrect type in discriminated union type

[kettanaito]

🔎 Search Terms

quick info, union, discriminated union, wrong info.

🕗 Version & Regression Information

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

⏯ Playground Link

https://www.typescriptlang.org/play?#code/C4TwDgpgBAGlC8UDeAoKUB2BDAthAXFAOQBWA9gBYZFQA+xA1lsBDfQM7ABOAlhgOZQAZMgC+KUcKgAKNMjnY8hTrwFSk49AG0GEEMu59+AXUJYMICXXnpFBYuSpE57MngAKXMmEIAjMmQANhDmEnL0qOi2uPZETCzOUVDxEADKkADGPABmPBkA0nqESFAZZACuGMCEGOU4vhBcUJrNKACUKCjSJXaEROYgALR2RAA0UFiEAIzjvoTc5RDjrkpQUwBMAMzNbVDszDzsuRDssJ0A9OdQABJkAG6NUPePAEQrEJ7eLwB0UAAqFGgAEdynkGFA+NkyHssCBTjxgERTv4giEMChLlAAO4UHjBcZ8KDZLAZYAExGnF4DF4yYmBQKnSoAE0eWCgODIXGgYC5OEO7B4DwhGBZAA89jx+NhgOUuW1vl0ejE+o5qMs3B8vD4oAtoKJdvtgIdjqcYJ0UEA

💻 Code

type X = {
  name: 'john' | 'kate' | string & {}
} & (
  {
  name: string & {}
  [key: string]: any
} | {
  name: 'john'
  someProp: boolean
}
  | {
    name: 'kate'
    kateSpecificKey: { count: number }
  }
)

({ name: 'any-name', a: 1, b: true, some: 123 }) satisfies X

// Hover over "someProp". The quick info says it's boolean
// while, in fact, it's "any" (falls under a more premissive index signature).
({ name: 'john', someProp: true }) satisfies X

🙁 Actual behavior

The quick info prop for someProp displays boolean as if the object matches the discriminated union. It doesn't, as you can observe from the actual type validation—someProp is still any, matching a more permissive index signature.

🙂 Expected behavior

The quick info must display someProp correctly—as any.

Additional information about the issue

This is a purely visual issue. The type validation is performed correctly.

[Andarist]

This one is correct. someProp: true has a boolean type. The purpose of satisfies is to keep the expression's type (and influence it with some contextual type information). As long as the expression's type is assignable to the satisfies operand that's all good.

There is a bug there though but it's a different one:

({ name: 'john', someProp: 'wrong!' }) satisfies X

If we hover over someProp here we might see this:

(property) someProp: boolean

but we really should see:

(property) someProp: string

[kettanaito]

Thanks for the clarification, @Andarist! Also, if this is a beginner-friendly issue, you may navigate me around and I could be able to contribute 🙏

[Andarist]

If you are up for it we could try to schedule a pairing session.

[kettanaito]

I would love to. Let's sync in Twitter/Discord and have this issue fixed.