Repository navigation
Unexpected union type between generic and non-generic function #12970
Description
TypeScript Version: nightly (2.2.0)
Code
function id<T>(x: T): T {
return x;
}
function stringId(x: string): string {
return x;
}
function numberId(x: number): number {
return x;
}
// OK: ((x: string) => string) | ((x: number) => number)
const f = true ? numberId : stringId;
// Actual: <T>(x: T) => T
// Expected: (x: string) => string
const g = true ? id : stringId;Expected behavior:
Union between a function and a generic function should yield the most specific type, not the most general one.
Activity
JsonFreeman commentedon Mar 22, 2017
I agree with the expected behavior. I also wonder if it would be reasonable to not collapse the union and keep both constituents.
gcnew commentedon Jun 9, 2017
Fixed by #16368