🔎 Search Terms

generic, infer, LSP, reference

🕗 Version & Regression Information

v5.8.3

⏯ Playground Link

🎢🎢🎢 TS Playground 🎢🎢🎢

💻 Code

type SpecialString = `##${string}`
type Style = { foo?: SpecialString }
export interface StyleFn {
	<T extends Style = Style>(styles: T): T[]
}
const style: StyleFn = (...styles) => styles

style({ foo: '##xx' })  // ❌ hover fails, only the value
style({ foo: '##xx' } satisfies Style) // ✅ hover works
style({ foo: 'xx' }) // ✅ hover works

🙁 Actual behavior

When calling a generic function that infers its type argument from an object parameter, the LSP fails to preserve the type reference, even though the typecheck works as expected.

• Hovering over the property value (someValue) inside the function call does not show the expected type.
• Go to Definition does not work. TypeScript cannot navigate to the original type definition.
• If the argument is explicitly asserted with satisfies, or if the line has a type error the reference works.

🙂 Expected behavior

When calling a generic function that infers its type parameter from an object argument, the LSP should preserve type references for all inferred properties, even when no explicit type assertion (like satisfies) is used.

Additional information about the issue

No response