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spreading generic type disables excess property checking #30129
Description
TypeScript Version: 3.3.3333
Search Terms: generic spread
Code
function spread<T extends {foo: string}>(p: T): {foo: string} {
return {...p, bar: ''};
}Expected behavior:
Excess property error for bar.
Actual behavior:
No error.
Activity
akozhemiakin commentedon Mar 31, 2020
The problem is actually more generic, not only about excess properties.
I believe this one must not typecheck, but it is.
That way we can not only add excess properties, but also get invalid object as a result. For example:
This one returns
{ foo: number, bar: boolean }but typescript believes it is{ foo: string }